97 TAHOE 5.7L VORTEC WON'T START...GM Merlin ideas?


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mwhughes
10-05-2004, 02:47 PM
The engine turns over but won't start. Therefore we did a new distributor, new coil, new fuel pump, new fuel filter, valve job and timing chain , all done at the same time. Spark plug wires have been checked and are in the correct firing order. Cam shaft sensor and Crank shaft sensor are both good. The engine has been timed according to protocol for timing a non-running engine. Good fuel pressure. Good spark. It still won't run. The intitial problem was the engine turned over but wouldn't start. All this work done and, the engine turns over but won't start. 130,000 miles. Any ideas? Could the computer be bad and how do I check that? Last resort, a trip to the dealer via a flatbed.

thanx,
Michael

aero246
10-06-2004, 03:20 AM
Check your timing chain. It may be broken.

mwhughes
10-06-2004, 12:00 PM
Hey aero246:

Thanx for the reply, but we replaced the timing chain as well. That has been double checked to this point. More importanlty, the crank shaft sensor has also been checked.

Therefore we did a new distributor, new coil, new fuel pump, new fuel filter, valve job and timing chain , all done at the same time.

thanx,
Michael

EmesiS
11-07-2004, 05:59 PM
Do you hear your fuel pump starting up when you turn the ignition key? If not check the fuel pump relay, this is something simple but it may have been missed. If you suspect that might be it, take it out and tap it on a hard surface to unstick the contacts and put it back in and try to start again. This happened to me because I would not hear the fuel pump kick in before I started the engine. And of course the first thing a dealer wants to do is replace the fuel pump. So I tried a little troubleshooting myself which started with the fuel filter and then the relay. Hope this helps.

GMMerlin
11-10-2004, 01:13 PM
The engine turns over but won't start. Therefore we did a new distributor, new coil, new fuel pump, new fuel filter, valve job and timing chain , all done at the same time. Spark plug wires have been checked and are in the correct firing order. Cam shaft sensor and Crank shaft sensor are both good. The engine has been timed according to protocol for timing a non-running engine. Good fuel pressure. Good spark. It still won't run. The intitial problem was the engine turned over but wouldn't start. All this work done and, the engine turns over but won't start. 130,000 miles. Any ideas? Could the computer be bad and how do I check that? Last resort, a trip to the dealer via a flatbed.

thanx,
Michael

Do you have fuel pressure (around 60-65 psi key on engine off)?
I would venture to say if you have fuel pressure and spark, I would look towards the injectors as the cause of your problem.
2 things could be happening.
1. the injectors are not being triggered by the PCM..causes, no power to the injectors or the PCM is not grounding the injector
2. There is a possibility that if you have spark, fuel pressure and injector pulse then the injectors are stuck shut. this system uses a poppet valve on the end of the injector to provide fuel..the poppet is a mechanical ball and seat injector that can stick.

MyHoe
11-12-2004, 10:24 AM
I had the same problem, It turned out to be my Fuel Pump. The damn thing was 200 bucks just for the pump. You also need PLASTIC line tool. The metal one from auto parts store didnt work. I hoped it was the Relay but no luck, had to come out of pocket.

Tagahoe
12-16-2004, 08:42 PM
I have that same problem, but mine sometimes starts up fine. I can drive it around, park it, go to start it up the next day and it wont start, then a few hours later it will start. what the hell is that? I've done a tune-up, fuel pump is new and working, fuel filter is new, and changed the ignition coil, any ideas?

Tagahoe
12-17-2004, 10:47 AM
any ideas anyone. went to start it this morning to take it to get check, and sure enough it wouldnt start, even though it started all lastnight. damn it!

Tagahoe
12-17-2004, 06:00 PM
Well i heard it is the Fuel Pressure Regulator. Anyone ever change one out?

Tagahoe
12-26-2004, 10:51 PM
well i change the fuel pressure regualtor and everything worked fine, until today. i went to start it after driving it all day, and it wouldnt turnover again. what the hell is it?

GMMerlin
12-27-2004, 07:34 PM
well i change the fuel pressure regualtor and everything worked fine, until today. i went to start it after driving it all day, and it wouldnt turnover again. what the hell is it?

So what is going on? Is this a spins and no start or a will not turn over problem?

Tagahoe
12-27-2004, 07:42 PM
I guess I have to say a spin and no start, cause it is turning over, just not starting. Like I said, sometimes it starts fine and runs fine.

krunt
01-07-2005, 05:24 PM
I had a problem like that. It turned out the Passloc was kicking in. Check to see if the security light is flashing with the key on after you try to start. If it is flashing leave the key on until it stops thenturn it off and try to start it. I read something about these going when the wires rub underneath the dash. I sent mine out and had to replace a module in the aftermarket alarm. No problems since X

Tagahoe
01-09-2005, 05:39 PM
Nope, its not flashing, but i tried it anyway, and nothing.

ponchonutty
01-09-2005, 08:29 PM
Had a desperate person call stating their '98 Tahoe won't start. It will crank but not fire. Said alarm shop wouldn't look at it because they said they knew it wasn't the alarm/remote start(Viper 781xp).
Dealer said it had to be the aftermarket items and said to remove them first.

So, I tried to walk him through some things over the phone. I mention basically what all was said above. He said he had replaced the fuelpump a few months ago and the truck ran fine. Then about 6 weeks later, it started chucking then wouldn't restart. He said he replaced the fuelpump again along with the fuel filter but still no fire. He later on replaced the fuelpump relay but same outcome.

After he towed it in I began to pick it apart. I looked at the pump relay and even jumpered the wire but it never came on. Looked at the PK2 light on the dash and it behave normally. So, I dropped the tank because I metered the gray wire at the pump relay but it didn't show any ground. Took out the pump and inspected. It was obviously new. I rigged the pump with my 12v drill battery and it worked. Checked the connector on the pump and it metered fine. Looked at the plug/harness that goes from the relay to the pump. The gray wire was fine but noticed the black ground wire was pushed back. Replaced the pin and wire, all is fine now.

cwong
01-10-2005, 09:55 AM
After he towed it in I began to pick it apart. I looked at the pump relay and even jumpered the wire but it never came on. Looked at the PK2 light on the dash and it behave normally. So, I dropped the tank because I metered the gray wire at the pump relay but it didn't show any ground. Took out the pump and inspected. It was obviously new. I rigged the pump with my 12v drill battery and it worked. Checked the connector on the pump and it metered fine. Looked at the plug/harness that goes from the relay to the pump. The gray wire was fine but noticed the black ground wire was pushed back. Replaced the pin and wire, all is fine now.[/QUOTE]

ponchonutty:
Where is this black groud wire?
Is it by the relay panel or by the fuel pump?

Thanx...

ponchonutty
01-10-2005, 08:07 PM
After he towed it in I began to pick it apart. I looked at the pump relay and even jumpered the wire but it never came on. Looked at the PK2 light on the dash and it behave normally. So, I dropped the tank because I metered the gray wire at the pump relay but it didn't show any ground. Took out the pump and inspected. It was obviously new. I rigged the pump with my 12v drill battery and it worked. Checked the connector on the pump and it metered fine. Looked at the plug/harness that goes from the relay to the pump. The gray wire was fine but noticed the black ground wire was pushed back. Replaced the pin and wire, all is fine now.

ponchonutty:
Where is this black groud wire?
Is it by the relay panel or by the fuel pump?

Thanx...[/QUOTE]
Unfortunately, it is the plug on top of the fuelpump. If you have skinny arms, you can reach on top and get it unplugged and pull it out. But, you gotta know what you are trying to unplug since you can not see it.

kerspse
01-13-2005, 01:05 PM
Your Fuel Pump is going bad. Replace it now or get stranded.

ponchonutty
01-13-2005, 06:47 PM
Your Fuel Pump is going bad. Replace it now or get stranded.
Who are you replying to? You can't assume anything. Just like this last Tahoe I looked at. Who knows how many pumps the guy would have installed on his own!!! :loser:

listo
05-26-2005, 10:42 AM
Im Having The Same Problem Would Someone Post Step By Step Trouble Shooting guides . What Do I Chech First And So On. Also Provide Location Of Parts To Be Checked. Thank You

txgearhead
05-27-2005, 01:53 AM
Turning Over/No start - Interesting thing I came across a few weeks ago. The fuel pump has a sensor that checks for unwanted air (pump gets dry). If the pump thinks it is dry, it cuts off to protect itself. Afterwards, it will act just like you ran out of fuel. It'll Turn over, but won't start until you get some more fuel. I was low on fuel, 2nd to the last red line and was headed up hill and punched to get around some traffic. The effect of both going uphill and harder than normal accelleration forced the fuel away from the pump and next thing I'm doing is muscling this rig around a curve! I parked facing downhill and it would not start. I put 2 gals of gas and it fired right up as if nothing was ever wrong. Not the fix for your prob., but something to keep in mind.

My experiences w\ the Passlock engaging has always centered around trying to turn the key too fast to start or to turn off then trying to start again. I purposely sit and wait for all the dash lights to go off before I start and pause for just a second in park before I turn off the ignition. It seems I wasn't letting the Passlock recognize the key, so it shut off. I haven't had a problem since

Food for thought, Good luck!

timaah
06-14-2009, 10:38 PM
I've been having the same problems with my '99 C1500 for the past few years. Only mine is a bit different. If it rains or it is very humid my truck will not start. I have replaced the coil, ICM, Dist. cap, rotor, sensor under the rotor, plug wires, plugs, crank shaft position sensor, fuel pump, fuel pump connector plug, knock sensor. I'm about to change out the fuel pressure regulator next. Tonight I had the truck running, then I shut it off. I then got the garden hose and watered down the distributor. I then tried to start the truck. It turned over and fired a little bit, but it would not start. It's looking like I have a distributor problem. Any one else out there have this problem?
Tim

baskentball
01-24-2010, 09:02 AM
I've been having the same problems with my '99 C1500 for the past few years. Only mine is a bit different. If it rains or it is very humid my truck will not start. I have replaced the coil, ICM, Dist. cap, rotor, sensor under the rotor, plug wires, plugs, crank shaft position sensor, fuel pump, fuel pump connector plug, knock sensor. I'm about to change out the fuel pressure regulator next. Tonight I had the truck running, then I shut it off. I then got the garden hose and watered down the distributor. I then tried to start the truck. It turned over and fired a little bit, but it would not start. It's looking like I have a distributor problem. Any one else out there have this problem?

Timaah,

Did you ever solve your problem? I believe my 97 Tahoe developed the same problem last week. I tried starting it last night, turns over a couple times then drags really hard. It acts like it wants to run (kind of rumbles then dies) but won't start. It was extremely humid and raining last night which is why it makes me think I have the same problem as you.

Thanks,
baskentball

EisMCA2
02-09-2010, 03:23 PM
I've been having the same problems with my '99 C1500 for the past few years. Only mine is a bit different. If it rains or it is very humid my truck will not start. I have replaced the coil, ICM, Dist. cap, rotor, sensor under the rotor, plug wires, plugs, crank shaft position sensor, fuel pump, fuel pump connector plug, knock sensor. I'm about to change out the fuel pressure regulator next. Tonight I had the truck running, then I shut it off. I then got the garden hose and watered down the distributor. I then tried to start the truck. It turned over and fired a little bit, but it would not start. It's looking like I have a distributor problem. Any one else out there have this problem?

baskentball or timaah,

My 97 Tahoe has been doing this for about 6 months now almost every time it rains or is extremely humid. Cranks over but will not start. It will sputter a few times and then kicks in like there never was a problem. Temperature doesn't seem to affect it. Once it does start, it runs great. Today it has completely given up and will not start. Has anyone figured this out? This seems to be a common problem. I'm going to finally try the fuel pressure regulator.

baskentball
02-09-2010, 09:46 PM
EisMCA2,

My problem ended up being my crankshaft position sensor. I stumbled upon the service bulletin (pasted below) while I was searching for Vortec timing problems.

Timaah was kind enough to email me after I posted. His problem ended up being the distributor cap.

Hope this helps,

baskentball

--------------------------------------------------------------------------

Engine - No/Hard/Slow Start/Backfire/Kickback

File In Section: 06 - Engine/Propulsion System

Bulletin No.: 00-06-04-014

Date: April, 2000

TECHNICAL

Subject:
No, Hard, or Slow Start, Backfire or "Kickback" During
Crank/Start, "Grinding" or Unusual Noises During Crank, DTC P0338
(Replace Crankshaft Position Sensor)

Models:
1999-2000 Cadillac Escalade
1995-2000 Chevrolet and GMC SIT Models
1996-2000 Chevrolet and GMC C/K, M/L, G, P Models
1996-2000 Oldsmobile Bravada
with 4.3 L, 5.0 L, 5.7 L or 7.4 L Engine
(VINs W, X, M, R, J RPOs L35, LF6, L30, L31, L29)

Condition:
Some customers may comment on one or more of the following conditions:

^ Backfire during crank/start
^ "Kickback" during crank/start
^ "No" start
^ "Slow" or "hard" start/crank
^ "Grinding" or unusual noises during crank/start
^ Cracked or broken engine block at the starter boss
^ Broken starter drive housing
^ Broken starter ring gear on flywheel
^ Any combination of the above

Cause:
A condition may exist that allows the crankshaft position sensor to command up to 50 extra degrees of spark advance during engine cranking only. This in turn exposes the engine to higher than normal cylinder pressures which may result in an inoperative condition to the starter drive housing, the engine flywheel starter ring gear, or the engine block at the outside edge of the starter boss.

Correction:
Inspect for a stored powertrain DTC code P0338. This DTC will NOT illuminate the "Service Engine Soon" light. If this code is stored, the Crankshaft Position Sensor, P/N 10456607, MUST be replaced and the remaining components inspected for damage (engine block at the starter boss, the starter drive housing, and the engine flywheel starter ring gear).

Notice : When DTC code P0338 is set, failure to replace the Crankshaft Position Sensor could result in repeated inoperative conditions of the starter or flywheel.

Important : Some flywheel wear is normal; broken or missing teeth and/or cracks, are not normal

baskentball
02-09-2010, 09:49 PM
I wasn't for sure if you would get notified of my other reply. It's posted below.

Thanks

EisMCA2
02-09-2010, 11:15 PM
Thanks baskentball,

Got it going now. It apparently is the crankshaft position sensor. I did replace the cap and rotor and it's running.

Anyway, I've noticed a lot of people with this same problem so maybe this will help other bone-heads like me. I'm not a mechanic so this may not be exact terms.

I've been messing with this for about a year. Usually it would start after several really rough cranks and then it would run just fine. Today it just wouldn't start. Even after recharging the battery for another go around. The fact that it happened every time it rained kept throwing me. Made me think it was a pressure problem which made sense that it could affect a fuel pressure regulator if it was failing. But the fact that temperature never seemed to affect it made me wonder. The humidity thing led me to think I should look at the distributor again. When trying to start it, it seemed like it was advanced too much and was fighting against itself. I unplugged the coil wire so it couldn't fire and it turned smoothly when cranking. Turned the engine to top dead center on 1. I figured out later that the notch on dampener lines up with notch on the block. I replaced the cap and rotor since they were a bit worn. I marked the direction the rotor was facing and when I put the cap on, I adjusted the distributor so that the #1 terminal was dead on with the rotor (follow the raised area on the cap from the #1 plug wire and this will let you see where the #1 terminal lines up). By this time the battery was recharged (ran it down while trying to start it all day). It started up just fine and is running great. It now gives me a check engine light (never did before). The code is for the crankshaft position sensor. So, my next move is to hope it doesn't crap out when it rains before I can get the crankshaft position sensor replaced. Seems like the new cap and rotor along with adjusting the distributor fixed it but I am going to do the crankshaft position sensor as well. Tired of getting caught in the rain. This may or may not help but I would have liked to have read this a year ago. Thanks.

outlaw24
02-22-2010, 11:38 AM
EisMCA2,
Did the Crankcase Position Sensor work for you too ? Has anyone heard. I have the same basic problem except I am getting a random misfire to multiple cylinders on the days that it runs. 95 % of the time its running you do not feel the misfires. Like everyone else almost everything has been replaced. - Outlaw24

EisMCA2
02-22-2010, 08:26 PM
Did the Crankcase Position Sensor work for you too?

Outlaw24,

When I was having the problem, it would run great once it started. Never felt any misfires. All I ended up doing was adjusting the distributor and changing the cap & rotor. I still have an engine light and the code says it is the crankcase position sensor but I just need to wipe that out. It has been starting like it did when it was new. From what I understand for this setup is that the computer adjusts the timing, not the distributor but if the distributor gets any farther than 10-12 degrees off, it can't accommodate. My problem seems like it was caused by the distributor being farther off than 10-12 degrees. All I did was mark where the rotor was pointing when #1 cylinder was at top dead center. Then when I put the cap back on I adjusted the distributor to line up #1 terminal with the mark I made for the rotor position. I still haven't figured out why it only did this when it was really humid or raining but it is running great now and I spent less than $50. I hope this helps.

EisMCA2

rr7774
03-19-2010, 08:36 PM
check ur ignition switch , when you turn the key three wire attached to plug when turn the key could have canm e off in the colum....security alarm system coul be messing with it.

techmike
04-17-2011, 08:47 PM
I have had the same problem lately with the Vortec 5.7 in my '97 Tahoe. It has 192,000 miles. Runs Great! Shut it off, and sometimes won't start back up!

Anyway, the other day I was driving and came to a stop sign. It DIED! Then the usual, cranking and cranking...still nothing.

For the heck of it, I unscrewed the gas cap, cranked and fired right up! Fuel pump was just replaced. Wires and distributor are new.

Can anyone else try this when theirs does this? Was it just a fluke?

ERICWILS
12-27-2011, 03:26 PM
After you replaced your crank sensor did you have to perform a crank relearn prcedure?

Chetco
12-27-2011, 06:18 PM
Thanks for all the ideas since mt 99 tajoe is turning over but not starting.

motobtn
01-24-2012, 10:33 AM
Hello All-
So I have to say thank you for all of you who have posted so far, these forums are very helpful.
I am having a very similar issue, and could use some more help.
I recently purchases a 98 5.7L K1500 that started fine when I first picked it up and has had issues ever since. It will crank and crank, almost fire, sputter, but not fire. I started by trying the basics, cam and crankshaft sensors, timed it, and replaced the fuel filter. Nothing worked, until I got it into the garage and heated it up and it started right up. I had heard great things on the MFI conversion, and decided I would try that first, even knowing my fuel pressure was a little low, 52-57psi, because the new Delphi Fuel Pump was only about a year old and I thought the new MFI system might not need as much pressure as the stock SCPI. Did the conversion, and the thing started great for a couple days, then back to the same crank and crank with no fire. So I dumped a can of HEET in just to see what happened, and she roared on barely touching the key. At this point I though maybe bad gas, but it didn't start a couple days later, so then I thought maybe it was the extra octane that compensated for low fuel pressure. So i replaced the fuel pump, and it started for 2 days, and now I am back to no start! I don't really want to just THROW parts at it, but if this is all I have left, then maybe I will.
So here are my thoughts on the last of the possibilities. Please let me know where you would start.
1) Weak Coil
2) Bad Rotor
3) Bad Cap
4)Throttle Position Sensor
5)Temp Control Sensor...CTS right?
6) IAT sensor
7)Compression

Once it starts, it runs great, but it is cold here now and every time it doesn't start, I scramble to get another ride etc to work, and want to know what fixed it when I fix it.

Please, any thoughts would be great on trying to narrow it down as all these parts would be a couple hundred. Also, haven't looked at the compression yet, but does anyone else think that makes sense. A guy at chevy suggested I check that, but I have never read anything about that in all the forums I have been looking at lately. His theory was if I have bad compression, it means that the rings aren't sealing and the gas is just flowing around. This doesn't quite add up to me based on that when it starts it runs so well and I get no codes, but maybe I am wrong here.

Thanks!

j cAT
01-24-2012, 03:25 PM
poor cold start and no codes can be low fuel pressures or the ECT/CTS coolant sensor to the computer/pcm/vcm is out of spec.

also connections to it.

after warm up it runs fine..how can it be compression or other engine problems ?

old contaminated fuel the kind we use now will cause poor cold start if a few months old.

motobtn
01-24-2012, 03:59 PM
I agree that it is hard to believe it is compression, but he was trying to tell me that once it fired the pistons rings would warm up and seal...basically BS to me which is why I came here for more opinions! :)

It isn't low fuel pressure as I am at 60 and above now with the new pump, and the new MFI injectors have a new fuel pressure reg with them. There is fresh gas in it, and the other tank got a can a HEET, so I think the gas is ruled out unless is was REAL bad...but I am not sure how that would happen.

I will replace the ECT first I think, then Dist. Cap, then rotor.

I mean the thing runs wonderful when it starts, and sometimes it starts dead cold, but once it doesn't start, it doesn't start until it warms up again is what I have experienced so far. I am going to try and get work done on it tonight or tomorrow night, and will post results as they come. I won't know anything for sure, as the last couple times I have thought it was fixed, it only lasted a day or two, but I will still keep up the posts as time goes on.
However, and more comments are definitely welcome.

Thanks again everyone!

j cAT
01-24-2012, 06:59 PM
the ect is about 20.oo...if it is original its most likely out of spec.

I always replace the distributor cap and rotor as a set made by the same manufacturer.

bad cap/rotor/distributor etc would cause poor high rpm run. as the arcing would be created at the higher rpm.

motobtn
01-24-2012, 08:29 PM
Well, new cap, rotor and cts...no go. Unplugged the battery to see if it "resets" everything. I just don't get why I would replace the cap and rotor when I have spark. Should I try the cool or wires for spark quality?!
Thanks for all the help!

j cAT
01-24-2012, 08:54 PM
Well, new cap, rotor and cts...no go. Unplugged the battery to see if it "resets" everything. I just don't get why I would replace the cap and rotor when I have spark. Should I try the cool or wires for spark quality?!
Thanks for all the help!

you stated you where going to replace the cap ////then rotor ///// all I stated is when you replace cap you should also replace rotor of the same manufacturer and I added this would in most cases not cause a poor cold start ....these if bad would cause problems at the higher rpm.

the spark quality if bad would cause engine to throw codes and run like crap........

the coolant sensor will screw up cold start...............

motobtn
01-24-2012, 09:09 PM
I apologize, I didn't mean to come off upset about installing the cap and rotor. I have been told by many it has fixed the problem, so for a few bucks why not. The coolant sensor is replaced now too, any thing I need to do to initialize it or relearn it or anything. Could the engine be flooded from extended cranking by now and need to sit over night?
I truly do appreciate the help, just running out of stuff to try!
Thanks!
Adam

j cAT
01-25-2012, 07:12 AM
I apologize, I didn't mean to come off upset about installing the cap and rotor. I have been told by many it has fixed the problem, so for a few bucks why not. The coolant sensor is replaced now too, any thing I need to do to initialize it or relearn it or anything. Could the engine be flooded from extended cranking by now and need to sit over night?
I truly do appreciate the help, just running out of stuff to try!
Thanks!
Adam


see if the plugs are fouled. see if wet with fuel and black.

check fuel pressure again with key on engine off and see if the fuel pressure holds and not drops off. if it drops off this may mean injectors leaking. this will flood engine.

j cAT
01-25-2012, 07:41 AM
I apologize, I didn't mean to come off upset about installing the cap and rotor. I have been told by many it has fixed the problem, so for a few bucks why not. The coolant sensor is replaced now too, any thing I need to do to initialize it or relearn it or anything. Could the engine be flooded from extended cranking by now and need to sit over night?
I truly do appreciate the help, just running out of stuff to try!
Thanks!
Adam

on your vehicle you need 60-65psi fuel pressure. not sure you are aware of this.

motobtn
01-25-2012, 09:05 AM
The fuel pressure when key on, engine off is 60psi.
I ended up letting the battery charge last night with the neg. term. disconnected, and then cranked on it for about 10sec at 9pm and it fired up! (this has happened in the past after I have had trouble starting it...would this essentially be flooded?! It had sat for about 3 hours before this latest attempt to start) Anyways, got it started this morning again after a night of sitting outside, not too cold, but probably high teens.
I am going to try starting after work again, then again in the morning, and repeat process for a couple days before relying on it to drive as this has happened this same way several times before now.

My biggest question at this point is this. The truck didn't start yesterday morning, and I cranked on it a decent amount. I then cranked on it a bit when I got home 10 hours later, with no luck and a weaker battery. I changed the CTS, put the charger on for a bit, no start. I changed the cap and rotor, still no start. I disconnected the negative again hoping it would reset the PCM which I was thinking might need to happen to "Recalibrate" itself...if it even does this. After sitting for 3 hours with the neg. detached and the battery well charged, it took some cranking, but fired up.Does this make sense that this would happen, or am I going to be stuck without start in a couple days?

Anybody want to take a guess here? I am 50/50 to tell you the truth as this same thing has happened a few times now.

I will check plugs next and probably throw a new set in just because it is easy and that would give me a new BW rotor, BW cap, and plugs, with relatively new BW wires...new fuel pump with ground connection cleaned and spray painted with rustoleum to help prevent rust, new MFI conversion, and a new CTS, Cam Sensor and Crank Shaft Sensor! If this doesn't work, I will get back to you and let you know. Thanks again for all the help, and any other thoughts or test would be great to hear. I will probably try to test all the components I pulled the best I can to determine what was actually bad and what was in spec. My hunch is a few different things were playing badly together and if I hadn't changed them now, I would have down the road...ie fuel pump, injectors, CTS.

Thanks again to all for their help, and hopefully this will help others as much as others have helped me!

j cAT
01-25-2012, 10:08 AM
with key on and the engine off , the fuel pressure must be 60-65psi. and hold for 15 min or so. if it drops off more than a few psi then this may indicate the injecotrs are leaking or other items reg/fuel pump.fuel line.

motobtn
01-25-2012, 10:11 AM
Thanks! I definitely didn't wait that long to see if it held, so I will check that and post back if it drops. I will say, I was expecting closer to 65 with a brand new pump and filter...

tempfixit
01-25-2012, 12:11 PM
I recommend that when you change the plugs check the compression while the plugs are out. Then you know if compression is good or not.

motobtn
01-25-2012, 12:13 PM
Will do! Thanks!

777stickman
01-25-2012, 07:11 PM
In response to a question on the ECT needing to re-learn or be "flashed" the answer is NO.

As to the Crank Sensor (CKP) being replaced, this will need the "CKP variation learn procedure" accomplished. This requires a high end scan tool in the hands of competent technician.

motobtn
01-26-2012, 09:30 AM
Well, it started up again today, and I checked the IAT and it was close to the CTS, which matched spec. I also checked fuel pressure for 15min with key on engine off, and it help 60psi. Hopefully this is fixed, just a little gunshy after thinking I have fixed it a few times now. Just need some real cold weather to verify.
That being said, and it has been a while since I haven't owned a diesel or newer gas vehicle, should I NEED to put HEET in when it is cold, or is that just covering something up?
I know a lot of people here in MN will just throw in some HEET when their cars won't start, but I feel that shouldn't need to be done unless something isn't right...is this correct thinking? thanks!

j cAT
01-26-2012, 11:39 AM
Well, it started up again today, and I checked the IAT and it was close to the CTS, which matched spec. I also checked fuel pressure for 15min with key on engine off, and it help 60psi. Hopefully this is fixed, just a little gunshy after thinking I have fixed it a few times now. Just need some real cold weather to verify.
That being said, and it has been a while since I haven't owned a diesel or newer gas vehicle, should I NEED to put HEET in when it is cold, or is that just covering something up?
I know a lot of people here in MN will just throw in some HEET when their cars won't start, but I feel that shouldn't need to be done unless something isn't right...is this correct thinking? thanks!


most times the fuel supplier causes water to be in your tank. keep tank around 1/-3/4 full..

if you have problems with fuel contamination go to another station and use some dry gas. this is done when you get below 10 deg f or the fuel purchased is bad.

motobtn
01-26-2012, 01:39 PM
most times the fuel supplier causes water to be in your tank. keep tank around 1/-3/4 full..

if you have problems with fuel contamination go to another station and use some dry gas. this is done when you get below 10 deg f or the fuel purchased is bad.


Thanks! My question is moreso, because it doesn't happen to me on new vehicles, is the HEET just covering up a deeper issue, or did older vehicles just need HEET sometimes, even when they were relatively new. basically, I have no problem using HEET when it is cold, but would rather just fix the issue if there is one to be fixed, assuming gas is good and temps are no lower than -30F.
Thanks!

j cAT
01-26-2012, 05:44 PM
Thanks! My question is moreso, because it doesn't happen to me on new vehicles, is the HEET just covering up a deeper issue, or did older vehicles just need HEET sometimes, even when they were relatively new. basically, I have no problem using HEET when it is cold, but would rather just fix the issue if there is one to be fixed, assuming gas is good and temps are no lower than -30F.
Thanks!

the problem this year is the weather is changing rapidly from cold to warm and lots of mositure. with alcohol fuels we use the water gets created all the more. the fuel filter will freeze. using heet/dry gas these products breakup the water so it mixes better with the fuel better and reduces the freezing. new vehicles do have less of an issue because the fuel tank has a great vapor sealing pressure controlling system. still this can not help when you buy bad fuel. some stations have been caught adding water. or the storage tank has a leak and water enters.

mikedlox
01-26-2012, 08:27 PM
I believe it is an electrical wiring problem.
I am having the same problem, Buy listening to yall have already done and the diagnosis that I performed on my truck im getting some of the same symptoms but with some extra ones. I found a melted wire and not to far from the underhood fuse box. This is a red wire with a white strip on it (not sure were it is going it is bundled with 3 or 4 other wires near the firewall on the drivers side it also runs behind the engine this wire was stuck to the ground wire) pulled it apart and fixed the shorted wire But still have the crank and no start problem. ALso for the extras, Im only getting +-10psi fuel pressure at the rail. so I disconnected the fuel filter and tested there still only 10psi with key on and engine off. Next I cut a hatch in the bed to gain access to fuel pump (YOUTUBE BABY) tested the connection with key on and get 12v for 2 seconds then have about 5 volts steady. Im also getting an evap code that comes and goes on its own but for the past year or two it has been there keeping my check engine light on but it never caused me to not be able to start and truck was runs good once started but havent been able to start it for about a week now. Any help will be greatly appreciated maybe some of the symptoms im having someone else might also

j cAT
01-26-2012, 09:56 PM
obviously having melted shorted wiring is a bad situation which needs attention. wires will need to be insulated and covered with a loom material as the vehicle was equipt or similar.

the fuel pump with the vehicle you have requires 60-65psi. therefore with 12volts for 2 sec and 10 psi you will never get it to start.

the fuel pump is shot and you will need a delphi fuel pump. if you use someother type wires/connectors may need be cut spliced to connect to the vehicle wire harness. also aftermarket pumps like airtex are short lived.

mikedlox
01-27-2012, 07:52 PM
so did anyone figure out anything...im going to get my truck scanned cause someone told me it could be a burnt out fusable link Have anyone ever heard of this or would anyone have a schematic of a 98 silverado pickup fuel pump wiring any help is appreciated

777stickman
01-27-2012, 10:27 PM
For less than $30 you can get all the schematics you want, and more, for 1 year.

http://alldatadiy.com/

Also, did you not read this from j cAT?

the fuel pump with the vehicle you have requires 60-65psi. therefore with 12volts for 2 sec and 10 psi you will never get it to start.

j cAT
01-28-2012, 01:32 PM
so did anyone figure out anything...im going to get my truck scanned cause someone told me it could be a burnt out fusable link Have anyone ever heard of this or would anyone have a schematic of a 98 silverado pickup fuel pump wiring any help is appreciated

first off there is no fuseable link. second with a bad fuel pump you will have no codes. there is no code for a failed pump.

bring the vehicle to a recommended repair shop and have them replace the pump. make sure it is a delphi or gm pump. no airtex pumps or it will not last more than a year if your lucky.

after its fixed keep fuel above 1/3 tank . this will keep pump from damage. you run out of gas a few times good bye pump............

mikedlox
01-28-2012, 06:05 PM
thanks a lot guys it was the pump, after extensive trouble shooting and reading thread after thread It was the pump not holding the pressure. After fixing the pump it fired right up. I couldint believe it was the pump because the pump was only 2 years old (maybe cause i dont drive that much)

j cAT
01-28-2012, 07:14 PM
thanks a lot guys it was the pump, after extensive trouble shooting and reading thread after thread It was the pump not holding the pressure. After fixing the pump it fired right up. I couldint believe it was the pump because the pump was only 2 years old (maybe cause i dont drive that much)

not using the vehicle creates fuel debris from the alcohol in it . things start growing. also water with condesation reacting with the fuel tank. fuel filters get pluged, pumps gets stressed.

low fuel levels destroy pumps. with a vehicle this old replace the fuel pump relay. if the pump does not get a strong 12 volts the pump will get damaged.

so what pump was installed today ? 2 years ago ? AIRTEX ? IF this is the pump used , no surprise to most that are experienced in this stuff...

if you know what to do and use these forums , this is a very easy problem to diagnose.

mikedlox
01-29-2012, 12:24 AM
well the pump was repaired due to empty pockets. I found out that the low psi was due to a leaking connection where the actual pump pushes into the plastic housing, to finally flow through that seethrough hose. found out the hard way that the pump is not actually held on by the plastic hose and clamp that is around the bottom of the seethrough hose but is pushed into a sort of rubber compression fitting that shrinks and wears out over time. I just rapped about 3 inches of duct tape around the plastic output on the actual pump then slid it into the rubber compression fitting in the housing. Next I put the pump back into the housing and put the pump back in the tank (after testing it in a bucket of water with a fuel tester attached to the (F)connecter on the top of the pump housing). Once back in the tank the truck took about 2 starts to fire up. Drove the truck for about an hour and shut it of about an half hour later I started it back up it started after the second try again but for the most part I can drive again. If your expeirienceing low fuel pressure its probably this connection were the pump is leaking internally and not allowing the fuel lines to build pressure. I will post my results as for how the truck is performing after this fix/repair

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