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

[mikedlox]

hopefully this will last until I get enough money saved up to get a good pump

[j cAT]

this is the experience of rick with airtex / non ac delco delphi fuel pumps. learning from the failure of others is much better than having you learn the expensive way. this post I agree with it is very good telling the whole story.


Rick Norwood
10-29-2008, 04:18 PM
In Oct. 2007, the original Fuel Pump in my 2000 4.3L 4dr, 2wd, Jimmy went out. I had the Fuel Pump replaced (long story) with a brand new Airtex brand aftermarket Fuel Pump and filter. Within 7 months, in April of 2008, I noticed the [COLOR=blue! important][COLOR=blue! important]truck[/color][/color] was getting harder and harder to start. It originally fired on the turn of the key, but progressively got to the point where the starter had to turn the engine over for 5-10 seconds before it would finally fire. Since the Pump was under warranty, my mechanic and I decided to R&R this pump before it left me stranded. Once the pump was out of the tank, we found that the Crimp style clamp holding the Flex hose onto the actual pump (inside of the Pump assembly, inside of the tank) was loose and probably leaking fuel and pressure back into the tank. We got a free Airtex Fuel Pump from the Auto Parts store and swapped out the Fuel Pump and filter. All seemed well until last week Monday, when this 6 month old Airtex pump started making a terrific howling, whining noise. I replaced the Fuel Filter again, even though it was also only 6 months old, but it didn’t help, the noise was very loud and could be heard during the 2 second prime cycle when nothing else was running, not to mention you could hear it while the engine was running. Knowing I was on borrowed time, I drove the truck until Thursday to try to drain as much of the fuel out as possible, when it finally left me stranded in the middle of the interstate. It just quit while driving at 40 MPH during rush hour. Luckily, I was in the right hand lane and was able to get out of traffic. Again, The Fuel pump was swapped out with; you guessed it, another brand new Airtex Fuel Pump, which has already started to show signs of trouble after 2 days. This brand new Airtex Fuel Pump does not seem to hold pressure once the pump (and Engine) is shut off. The next time you try to start the engine, if you don’t let the Prime Cycle finish the 2 second cycle when you first turn the key, the starter cranks until the system is primed. If you let the prime cycle finish, it starts normally.

Here are a few suggestions, tips, opinions, advice, call it what you want, but hopefully, someone will benefit from this and not make the same mistakes I made.

1, Never, never, never buy an Aftermarket Fuel pump. AC-Delco/Delphi OEM pumps are the only way to go, and they are not usually that much more money. If I had done this, I would have saved over $500 in labor costs. Bite the bullet and do it right the first time. You will be ahead in the long run. After 3 pumps I am qualified to make this statement.

2. Some new Aftermarket pumps have a different wiring harness connector that will require you to cut your old one off and connect their new one on. If you have to use a different connector, I recommend that you solder the wires instead of using the connectors that come in the box. However, if you replace your connector and have to go back to the original GM connector, it may cost you extra for a new connector.

3. Always replace the Fuel filter at least once a year. I cannot emphasize this enough! This is what in all likelihood caused my original Fuel Pump to go out. Too much back pressure kills these pumps. Always replace the Fuel Filter when you replace the Fuel Pump.

4. If your Fuel Pump starts to whine, howl or emit a loud whistle, you’re on borrowed time. Start planning for the inevitable R&R. Most Fuel Pumps will normally make some noise. To listen to your fuel pump while it seems to be running good, stand by the Gas Cap Door and have someone turn the key to “ON” without starting the engine and listen to the two second prime cycle for future reference and take note of any change in the sound.

4. If at all possible, if you have a choice, schedule your Fuel Pump replacement when the tank is almost empty. You and/or your mechanic will thank me later.

5. Once the Fuel Pump is out, inspect the inside of the tank for cleanliness. Also inspect the various hoses, lines and clamps and replace anything that could cause small leaks. This is so much easier to do when the tank is out.

6. Double check and inspect the new pump and gasket and make sure everything is the same. I have had Fuel Pump gaskets that came in the box with the new pump that were not thick enough to seal the tank and resulted in failure at the emissions station. I had to buy a new Gasket from the Dealership and re-do the job.

7. Lube the new Fuel Pump gasket with light grease during install to get a good seal.

now one other thing about your vehicle is reports that the fuel pump relay can fail causing the pump to run all the time.

good luck .

[motobtn]

OK, so it has been starting great and running great, so yesterday I put it to the test. Let it sit for 21 hours in 5F-30F, and this morning, at 10F, it wouldn't start. Cranked, almost caught(seemed like it was firing but just not enough to catch) but just wouldn't fully catch. Just dumped a can of heat in as it is sitting on the ice right now and I want to get it home, so I will let it sit for a bit and try again.

Any other thoughts? Could it just be the cold and i am going to have to put a higher ethanol gas it or heet regularly, or what else it left? What causes it to "catch" for a second, but then not start? Many times when I stop cranking it will shudder a bit like it is igniting something, but I just can't get to the bottom of this!

[j cAT]

Originally Posted by motobtn

OK, so it has been starting great and running great, so yesterday I put it to the test. Let it sit for 21 hours in 5F-30F, and this morning, at 10F, it wouldn't start. Cranked, almost caught(seemed like it was firing but just not enough to catch) but just wouldn't fully catch. Just dumped a can of heat in as it is sitting on the ice right now and I want to get it home, so I will let it sit for a bit and try again.

Any other thoughts? Could it just be the cold and i am going to have to put a higher ethanol gas it or heet regularly, or what else it left? What causes it to "catch" for a second, but then not start? Many times when I stop cranking it will shudder a bit like it is igniting something, but I just can't get to the bottom of this!

water is most likely the problem with the tests you have done so far. did you try another fuel depot ? also put some fuel in a approved container at the station and let it settle out see if it has water in it.

a quick start then stall could be the security system is the key is going bad ..not sure on your vehicle with that issue.

when cold out on a first starting with 10deg f temp , turn key to ignition on wait 2 sec. pump pedal 2X then crank . see if that does it.

[motobtn]

Alrighty, I think we are getting close, but could use some more advice yet.
I poured a bottle of heet in yesterday after it wouldn't fire up, waited a couple hours, and she fired right up.

From all this cranking, my starter is now shot! It takes many key "turns" after it has been sitting to finally catch, but I figured this would be happening as it has been worked pretty hard lately.

Anyways, I let it sit for 16hours yesterday and went to fire it up today, and, after getting the starter to engage, wanted to just crank and crank, would do the almost catch thing, shudder when I let the key go, but wouldn't start! So I tried again, but this time, when it was just "catching" I pumped the gas, and eventually, it started up! So, what are we thinking now? Basically, the whole engine spudders and shakes a lot of the time when I let go of the key after cranking, so I was able to get it fired up when I let go of the key and stepped on the gas. Could this still be a bad gas situation, or more timing related or what are the options.
I have it timed with a Tech2, still haven't gotten the crank sensor "relearned", but I am guessing that is more for overall performance and not starting.

Thanks!

[motobtn]

What are the chances it could be that the starter is too weak or drawing too much power? This occurred to me last night, and again today, and then I found this on another site. Would this make sense if I was able to get it to catch by pumping the pedal when it was "beginning to catch"?

"A less common cause is a worn starter that draws so many amps while cranking the engine that there’s not enough juice left to adequately power the ignition system and fuel injectors. Contributing factors might be a weak battery and/or loose or corroded battery cables."

[bigben19974x4]

I'm having the same problem with my tahoe. I've got spark and fuel pressure but it won't start. plugs cap and rotor and about 1 1/2 old new fuel pump and starter relays. if it sits a week and the battery dies ill jump it, it'll fire right up.

[j cAT]

Originally Posted by bigben19974x4

I'm having the same problem with my tahoe. I've got spark and fuel pressure but it won't start. plugs cap and rotor and about 1 1/2 old new fuel pump and starter relays. if it sits a week and the battery dies ill jump it, it'll fire right up.

you need 60-65 psi fuel pressure. any less no start.

[bigben19974x4]

so i watched the pressure for 15 min. and it dropped below 60 which should i change first the pressure regulator or the pump.

[j cAT]

Originally Posted by bigben19974x4

so i watched the pressure for 15 min. and it dropped below 60 which should i change first the pressure regulator or the pump.

if when placing the ignition to on with no cranking , and you get 60-65 psi , then the fuel is supply pressure is good. after a couple of seconds the pressure should drop a few psi and hold somewhat for about 15 min . this would mean you have no leak down like regulator/injectors or the fuel pump check valve in the fuel pump is bad.

if you had fuel supply issues , normally after a very short time the pressure would drop to zero.


do you have any sercuity light on. also an aftermarket security system ? these are things that can cause this issue. re-check for proper blue spark . add some fuel to intake see if it gets to run.

could be the computer/pcm is bad. this would prevent the injectors from opening . see if you get injector pulses on the ground side when cranking.

another item would be the ECT, if this is reporting the wrong engine temp this will not throw codes and also cause no or very poor start.

[Xgiusmc]

Okay alittle help hear. I have a 5.7l GMC 1999. I just won't start . I was in Parkng lot and wouldn't start. So I bought a pressure gauge and have no pressure . So I checked fuel pump. I bought a new one and replaceed it and the relay. Still no pressure . Please someone help me out. I can't work with no truck and I have no cash with. No truck.. This bits. Email me Please (xgiusmc@aol.com)

[j cAT]

Originally Posted by Xgiusmc

Okay alittle help hear. I have a 5.7l GMC 1999. I just won't start . I was in Parkng lot and wouldn't start. So I bought a pressure gauge and have no pressure . So I checked fuel pump. I bought a new one and replaceed it and the relay. Still no pressure . Please someone help me out. I can't work with no truck and I have no cash with. No truck.. This bits. Email me Please (xgiusmc@aol.com)

welcome to the autoforum. the problem you have could be a bad wire/fuse. using a voltmeter you check for voltages start at fuel pump relay. also make sure the ground connection at the fuel tank frame rail area is clean and secure. at the pump see if there is power and a ground. you could also bypass every thing using a 20a fused jumper and apply power to the fuel pump connector to see if you purchased a bad pump or if this is some non oem pump the connections made at the pump wiring is defective.

use delphi fuel pumps , DO NOT USE AIRTEX....

[jcass]

I have a 96 chevy k1500 5.0 liter. Having the same issues as a lot of you. I'm on the third fuel pump in a little over a year. Two of those being changed in the last 3 weeks. Got in it to go to work this morning and wouldn't start again. Fuel pump is not turning on again. I find it hard to believe that it has gone through 2 fuel pumps in 3 weeks. With this last fuel pump it ran for a week. The fuel pump prior to that it ran for 2 days. Checked the fuel relay with a meter and it read good. I guess it could still be bad. Any help is greatly appreciated.

[j cAT]

Originally Posted by jcass

I have a 96 chevy k1500 5.0 liter. Having the same issues as a lot of you. I'm on the third fuel pump in a little over a year. Two of those being changed in the last 3 weeks. Got in it to go to work this morning and wouldn't start again. Fuel pump is not turning on again. I find it hard to believe that it has gone through 2 fuel pumps in 3 weeks. With this last fuel pump it ran for a week. The fuel pump prior to that it ran for 2 days. Checked the fuel relay with a meter and it read good. I guess it could still be bad. Any help is greatly appreciated.

so did you read the prior post[s] ?

you have a delphi pump correct?

you keep the fuel above 1/4 at all times ?

you replace fuel filter every 30,ooomi ?

[jcass]

Yes done all of that. Fuel pumps are a/c delco.