93 Blazer 4.3 Vortec Runs like crap, then dies

[gverb1219]

My sons 93 Blazer, 4.3 Vortec has been having some running problems. It started about 6 months ago when it up and died coming home from Pennsylvania. Turned out that was because of the fuel pressure regulator. I put a new one in and everything was fine for a couple months, then it started acting up again. I replaced the regulator again and it seemed fine until yesterday. The engine starts runni9ng really rough, then stalls out. It will start again go for a bit and run like crap and sputter and shake and die again, then it wont start.
After it sits for an hour or so it will start up and run ok for a few miles and crap out all over again. It seems like it is flooding out. I have noticed that before this, it was getting really bad fuel mileage and there was always a strong smell of gas present.
I did notice that when I split the manifold to replace the regulator there was signs of gas inside the manifold (clean spotsaround the regulator side), but cant tell where it's coming from.

Any ideas..........I don't want to keep dumping money into it doing the trial and error bit.

Thanx
Gary

[MT-2500]

Proper testing is the key to not throwing parts at it.
Run a good fuel pressure test.
Is this the 4.3 W code engine?
When it quits is it losing spark or fuel?
WILL IT START BACK UP WITH A SQUIRT OF CARB CLEANER?
Any codes or check engine lights?
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 pressures.
Your start should be 60-61 lbs of pressure.
The 93 4.3 W or yours is 55/61 lbs 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 55/61 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post-back fuel pressure readings.

Remember a fuel pump pressure regulator controls the pressure and maintains a steady pressure depending on engine load and vacuum.
It has to be capable of producing higher pressure than the regulated pressure.

The fuel pressure controls pressure and can leak off or bypass pressure

[procaddytech]

What condition are the plastic flex lines under the plenum leading to the injector in? Sometimes they will get holes in them filling the intake with fuel. Check for leak-down as suggested above. The oxygen sensor may also be stuck low causing false enrichment. After runing rich for too long the O2 will get fouled and be covered in soot. Since it runs fine cold, it seems like the problem may be occuring when the vehicle enters closed loop operation, and the ECM uses sensors to control fuel delivery. If the O2 is stuck low, the ECM will continue adding fuel to try to get the O2 above the rich/lean cross-count values.

[gverb1219]

Originally Posted by procaddytech

What condition are the plastic flex lines under the plenum leading to the injector in? Sometimes they will get holes in them filling the intake with fuel. Check for leak-down as suggested above. The oxygen sensor may also be stuck low causing false enrichment. After runing rich for too long the O2 will get fouled and be covered in soot. Since it runs fine cold, it seems like the problem may be occuring when the vehicle enters closed loop operation, and the ECM uses sensors to control fuel delivery. If the O2 is stuck low, the ECM will continue adding fuel to try to get the O2 above the rich/lean cross-count values.

LMAO....................that post was over 3 years old......that Blazer is long gone............lol..

.............................but thanx anyway...........

[procaddytech]

Oh Duh! Did not even notice the date! I usually click "Latest" and read through. At least you got a laugh! What a brain fart.