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99 blazer 4.3L no spark


Tgibson_br
09-16-2007, 08:57 PM
I have a 99 blazer 4.3L vortec. Just recently my blazer died on me, i noticed for about a week that it was hesitating starting in the morning, only in the morning it seemed but during that period, it was humid out and moisture content was high, so i assumed moisture was getting into the distributer area. All of a sudden, it doesn't want to start. I've checked for spark from the plug wires and also from the ignition coil. Decided to replace the ignition coil, and distributer cap and rotor. Still no luck. I also decided to replace my crank sensor and with that done, it still does not want to start. Any ideas on how i could check this or know what could be wrong. I've scanned the vehicle and no codes came up. Any help would be greatly appreciated. Thank you.


Tim

82Stang
09-16-2007, 09:04 PM
Is it getting fuel and can you hear the fuel pump when turning the key on?

Tgibson_br
09-16-2007, 09:11 PM
yeah, the fuel pump will turn on when you turn the key, activates for a few seconds as it should, then shuts off again. I also can hear the relay clicking on and off when this all happens also.

82Stang
09-16-2007, 10:45 PM
Okay, if the fuel pump is working then lets move forward from that point. How about the fuel filter? It will cause stalling at lights and slowing down when getting clogged and even a no start condition when really clogged? I'd make sure the fuel filter is recent and not the problem.

Hope this helps.

Tgibson_br
09-17-2007, 01:15 PM
yeah, i just replaced the fuel pump and the fuel filter around spring time. april/mayish, in there. my fuel pump went completely dead on me. But i will have to check it out. Thank you.

Tgibson_br
09-18-2007, 02:51 PM
ok, i replaced the fuel filter today, and still no luck on the starting. If anyone knows, what is the psi that the fuel pressure should be at for my vehicle? when i bought a pressure gauge yesterday, it tested out to be at 44-45psi when the pump would activate and slightly held and dropped a few psi over time. Is that a low count? If so, i'm guessing that my pump is screwed up. :( Oh well, any feed back would be helpful, and any info on how i could test this b4 i drop the tank and take the pump out. Thank you.


Tim

MT-2500
09-18-2007, 03:57 PM
Fuel pressure is way low.
Jumper the fuel pump or bump the ign a couple of times to prime up fuel pump to full pressure.
But that does not explain the no spark.

If you have crank sensor signal or rpm signal and the coil is good check ign module.
MT

Do you have a scanner to see if the pcm/vcm is getting a rpm signal or crank sensor signal?
Any remote start or add on anti theft?

82Stang
09-18-2007, 05:50 PM
I agree with MT, an ignition module could also be the culprit. But first I'd get it scanned for any codes. Most auto parts stores will do it free.

Tgibson_br
09-18-2007, 06:34 PM
what type of scanner are we talking about? is it just the one that you plug into the OBD 2 port to scan the computer? or is it scanning the sensor itself somehow that i'm not aware of? I bought a scanner the other day and got no codes from my vehicle computer. As for the ignition control module, i did replace that.

Tgibson_br
09-18-2007, 06:36 PM
also, how would i jumper the fuel pump? I know i read about it somewhere, but not sure if what i read was the right thing. I did try to prime the pump a few times. Turn key to start, let it run. shut off. waited, then turned key to start. Didn't seem to be working. Would having the low pressure cause a nostart/no spark type situation? Thanks for the help

old_master
09-18-2007, 07:59 PM
In the underhood fuse box, find the fuel pump relay. About 1/4" in front of the relay is a single, recessed, open terminal, (nothing connected to it). That terminal is connected to the fuel pump circuit, (grey wire). Connect a fused, (10amp) jumper wire from battery positive to that terminal and the pump should run until you remove the jumper. With 45psi fuel pressure, the engine will not start, guaranteed!

Tgibson_br
09-19-2007, 06:00 PM
ok, i'm trying to test my fuel pressure from my filter to the pump, by using the pressure gauge i have, only to find out that i can't get the darn thing to thread on. i think my gauge might be just a hair to small than what i have on. any other ideas on how i might be able to test the pump. my pressure seems to still be low in the mid 40's and i would like to find if it's the pump causing the pressure loss. any other ideas?

Thanks

old_master
09-19-2007, 08:22 PM
There are two special tools: Each tool has a shut off valve, a service port for the fuel pressure gauge, and fittings on each end that attach to the fuel lines. One tool is installed in place of the fuel filter, and the other in the return line. The tools are used to isolate each component in the fuel system to determine where an internal leak is. The tools come in a set and are quite expensive. The alternative is go to your local hardware store and procure the necessary fittings to adapt your fuel gauge to the pressure line. If you're really creative, you can make the tools yourself. I made both of the tools for around $65.00 total, (A little more than the cost of a fuel pressure regulator). If you're serious about DIY, (do it yourself) not GIY (guess it yourself), the tools will save you some money in the long run. GM used different configurations of fuel line connections over the years, so another model year may be different than yours. Bottom line is you need to connect your pressure tester to the pressure line from the pump, then briefly energize the pump and check maximum pump output. Less than 75psi means time for a new pump. Another way to check max output is to slowly restrict the fuel return line and watch fuel pressure. That procedure is risky. If pressure is allowed to rise above 75psi, it can permanantly damage the fuel pressure regulator.

Tgibson_br
10-10-2007, 05:06 PM
alright everyone. i want to thank you for your help and support during this time, i don't know what i've done. but i managed to get my blazer started back up. i think it was a combo of different things. but i did replace alot of parts, and even my fuel filter. i now have another problem, it seems that my blazer is now misfiring. using my computer that i have, i let it run for a bit b4 scanning and got this code. P1351....manufacturer control ignition system or misfire. Any ideas on what this code could be talking about? i'm gonna do some research on it, but if anyone has had any experience with this code, could you let me know what you did to take care of it. Thank you all once again. I really appreciate the help. :grinno:

old_master
10-10-2007, 05:38 PM
What parts did you replace? It may be related to the DTC. If you did anything with the plug wires, recheck the firing order. On the passenger side, front to back on the distributor cap are cyls 2, 4, & 6, in that order. Driver side front to back is 3, 1, & 5.

82Stang
10-10-2007, 06:54 PM
I did hear of a person having the same code P1351 and called the dealer. They told him it was the coil wire(end might be split or bad). This person replaced that and had no more code. Don't know if this is your problem, but worth a shot.

Hope this helps.

Tgibson_br
10-11-2007, 02:20 PM
ok, here is the list of parts i replaced thru the whole thing, but sad to say now i'm on a different problem. i now have spark, but it seems to not be getting enough fuel i'm guessing. my fuel pressure, testing from the test valve behind throttle body is low, 50ish, which i've learned is not enough pressure, but for some reason, i can get it to fire up with starter fluid, but dies shortly thereafter when the fluid run dry. :disappoin As for parts, i replaced the ignition coil, distributer cap, and rotor, and the last part i replaced was the ignition control module. could have been that originally. now all i have left is to discover my current problem and fix it. I'm gonna do some more research b4 i start taking parts apart to check my injectors and such. Anymore feedback would be very helpful from you all. Again, i really appreciate it.

jordan_johnson1988
10-11-2007, 05:12 PM
My name is jordan and im having the same exact problem same modle and everything if any one knows what i should do please let me no. thanks

MT-2500
10-11-2007, 05:59 PM
My name is jordan and im having the same exact problem same modle and everything if any one knows what i should do please let me no. thanks


Welcome to AF.:grinyes:
It would be better if you started your own post on your problem.
Two different people on the same post gets two different confusing answers.
Just hit the New thread/post button and give us all of the info you can.
Also tell us if you have no spark or no fuel or both.
Give all of the info you can.
MT

Tgibson_br
10-17-2007, 09:41 AM
i have a question for you automotive gurus out there. lol. is there any way to test my fuel pressure regulator or to find out with out taking it apart if my engine is getting fuel into it? it seems that if i want my engine to start, i have to put starting fluid into it. it will run until it burns up the starting fluid, then immediatly stalls. I do have fuel pressure from the pump to the engine. (50/52 psi...kind of low i know.) but for some reason now i'm not getting any to the engine from what i can tell. :banghead: Getting confused with this blasted vehicle. lol, but i'm enjoying the learning experience i'm getting from it. thanks for the help.

Tim

MT-2500
10-17-2007, 10:00 AM
The injectors will not squirt fuel on a cold start if fuel pressure is under 60 lbs.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.

Tgibson_br
10-17-2007, 04:55 PM
ok, then it sounds like my fuel pump is bad then. since there is really no way for me to get it to start up, unless i use starter fluid, and even then it dies as soon as the starter fluid runs dry. i'm gonna have to say it would be that. i've replaced the pump once early this year/end of last year, can't really remember correctly. All i know is i did it and it sucked for doing it the first time. :cwm27:
would a bad pump that is not giving enough pressure still run, and act like it's doing it's job. Thx for the feed back.

MT-2500
10-17-2007, 05:25 PM
ok, then it sounds like my fuel pump is bad then. since there is really no way for me to get it to start up, unless i use starter fluid, and even then it dies as soon as the starter fluid runs dry. i'm gonna have to say it would be that. i've replaced the pump once early this year/end of last year, can't really remember correctly. All i know is i did it and it sucked for doing it the first time. :cwm27:
would a bad pump that is not giving enough pressure still run, and act like it's doing it's job. Thx for the feed back.

Do not jump the gun untill you have checked/tested it.
Many things besides a bad fuel pump can cause low fuel pressure.
Go threw the fuel pump testing I posted.
And post back pressure readings.
MT

Tgibson_br
10-20-2007, 10:08 AM
hey, another question for you. i know some people out there tell me to pinch off the return line to test the fuel pressure on my vehicle. Are they reffering to pinching it off near the pump itself, or is their another place i'm not knowing of? And what would be the best tool to use to pinch that off? Thank you

MT-2500
10-20-2007, 01:39 PM
hey, another question for you. i know some people out there tell me to pinch off the return line to test the fuel pressure on my vehicle. Are they reffering to pinching it off near the pump itself, or is their another place i'm not knowing of? And what would be the best tool to use to pinch that off? Thank you


Plugging the return line is safer.
Pinch at your own risk or with special pinch pliers.
There is usually a rubber line from engine to frame. \or just unplug or unbolt return line and plug off.

Tgibson_br
11-02-2007, 06:06 PM
alright, i got my blazer running finally, but now i'm into another minor problem. took it for a small drive to see if it would clear up or clean up any bad readings the computer would get. upon doing this, when i got the blazer to a certain speed nad tried to go faster, it would hesitate, or seem like it was sputtering. When i got home, first thing i did was checked my plug wires. had a similar problem on a cutlass supreme i used to own and found a wire touched heated metal and tore open and was causing a miss spark. Upon this, i found no bad wires, but found that the #2 wire was loose on the plug. got it back on, and gave another scan. got a scan about cylinder 2 misfiring...so i expected that was due to the loose wire. took it for another spin, and didn't get any hesitation. Brought it home and scanned again. (erased the codes b4 i went out), now i get this code p0300 random/multiple cylinder misfire detected. Any ideas on what might cause this. When i let my vehicle idle, it seems to be sputtering and hesitating some. i normally can only detect this at the idle stages or when driving slowly.

Also, to let you know, when i got spark back, and was testing the fuel pressure on the check valve up top, i noticed a wire disconnected. upon following and inspecting, i found that the coolant temp sensor connector part had become brittle and broke in half...replaced the part, and started right up. occasionally has trouble, but i think my battery is not fully charged yet. gonna leave it on the charger over nite. :). Thx for all the help so far guys. i really appreciate it. Now hopefully only to fix the misfire problem and hopefully all will be well for a bit. Thanks again.

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