97 4.3 Blazer stalls on hot days

[bobboo]

I have a 97 blazer 4X4 with a 4.3 engine, on hot days it will just quit while i am driving. if i let it sit for 5-10 min it will start right back up and way i go. about ten minutes later the same thing happens. Everything is in specs and i dont get a check engine light. Ive read many posts with the same problems and nobody seems to have a conclusion. i checked just about everything so any info would be great. A fix would be the best.

[MT-2500]

Originally Posted by bobboo

I have a 97 blazer 4X4 with a 4.3 engine, on hot days it will just quit while i am driving. if i let it sit for 5-10 min it will start right back up and way i go. about ten minutes later the same thing happens. Everything is in specs and i dont get a check engine light. Ive read many posts with the same problems and nobody seems to have a conclusion. i checked just about everything so any info would be great. A fix would be the best.

They are not looking very hard or doing any proper testing if they can not find the problem.
When it does it check for lose of spark to plugs or lose of fuel pressure.
Also a good engine capable scanner may have history or stored codes of freeze frames of the problem.

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.
Post back fuel pressure readings.

[bobboo]

Ive had it to three different shops and cannot find any problem. If it was fuel pressure wouldnt it be more consistant than just on very hot days. It started doing this last summer thats when it was checked with a pressure guage on it driving around for about an hour, pressure stayed mint the whole time. I put about 10000km on it over the winter, no problems, now that it is hot again if i drive for about an hour it will just up and quit. It gets fuel the whole time, so maybe the coil or something?????

[MT-2500]

Originally Posted by bobboo

Ive had it to three different shops and cannot find any problem. If it was fuel pressure wouldnt it be more consistant than just on very hot days. It started doing this last summer thats when it was checked with a pressure guage on it driving around for about an hour, pressure stayed mint the whole time. I put about 10000km on it over the winter, no problems, now that it is hot again if i drive for about an hour it will just up and quit. It gets fuel the whole time, so maybe the coil or something?????

You need to check it when it does it.
Confirm good fuel pressure when it quits.
CHECK FOR GOOD HOT SPARK TO ALL PLUGS WHEN IT DOES IT.

[viggy58]

ignition control module is going bad. as the ICM heats up, it begins to fail. happened on my dad's 96 trans am. same symptoms, no codes thrown, etc.

swapped it with the one on my 01 blazer for a day and the problem went away. bought a new module for the trans am and haven't had any problems since.

some places say they can test the ICM, but the test isnt very accurate. if you know anyone with a 96+ v6 or v8 gm/chevy, see if you can borrow theirs for a day, and see if the problem goes away. (cross reference the part number to make sure they are the same part)

[bobboo]

thanks for the reply. i will try to swap it as soon as i can get my hands on another one and i will let you know if it worked.