I have recently purchased a 95' Blazer with 4.3L Vortec CPFI that wasn't running. I installed a new fuel pump, new spider assembly, new which got it running. I also replaced the oil pressure sensor, PCV, ignition coil, ignition control module, cap & rotor, EGR w/ screen kit, and complete exhaust with new catalytic convertor.

The truck runs good but what started as once in a while after driving for 15 minutes it would begin to stall, hesitate, lose power when giving it throttle which would get progressively worse over a few minutes until it would die. Sometimes will restart but mostly not start unless sits for an hour. One time wouldn't restart at all until I pulled the battery positive then started and ran fine til I got it home. This symptom began intermittently on colder days but seems the hotter the outside temperature is, currently 80's and will do it consistently every time now. It could be the problem getting worse as the season progresses and not related.

The engine does not throw any codes, it is OBDII or 1.5. I was told I had a lower intake gasket leak that would need to be addressed in the near future. I was able to drive around with a fuel pressure gauge to check for fuel issues when problem occurred but held steady @ 55PSI and still had over 30PSI after an hour so I don't think it's fuel delivery issue.

I bought this car for my daughter and she wont drive it since she has been stuck too many times now and really invested way too much to sell without losing big. Any ideas? Thanks in advance!

 

How old is the fuel filter?

Auto or manual transmission?

 

No DTC's and no check engine light is a huge help, it means the problem is not something that the PCM monitors. 95 was a hodge podge year for Blazers, so we need to know which system you have.

Does the distributor cap look like this?

Does the engine look like this:

 

I'm reading this out of the FSM

Cuts out, misses:definition--Steady pulsation or jerking that follows engine speed, usually , more pronounced as engine load increases. The exhaust has steady spitting sound idle or low speed.

Do a compression check on all cylinders

Check for contaminated fuel. (you tested fuel pressure and replaced the fuel filter)

Test injector driver circuit- disconnect all injectors - connect multimeter or 12 volt test light between the harness terminals and note while cranking. If test light fails to blink at any connector, it is a faulty injector drive circuit, harness, connector or terminal.

Injector resistance- resistance should be between 1.37 and 1.77 ohms for CMFI at 68 degrees. resistance will be slightly more at higher temperatures.

Perform injector balance test- You need tester J 39021 to do this.

Spark plug wire resistance should not exceed 30,000 ohms
check spark plugs for wear, improper gap, burned electrodes or heavy deposits
With engine running, spray plug wires with fine mist to check for shorts.

Post a follow up of test results.

There are more tests

 

FSM? Would that be Haynes/Chilton or the "real" GM FSM?

 

I would rather use poison oak to wipe my A** with than use a haynes.

Nope, genuine Factory Service Manual. Bought two sets. One for the shop and one to tear every page out of and scan into my computer.

 

LOL, I agree, they're worthless. 3 different possibilities for engine controls in 95. I guess we have to wait for some answers from the OP now.

 

Thanks for all the input so far.

RamJam, Auto tranny, fuel filter changed last month.
CaptainHook, yes that is my cap and engine.

I guess I will do the plugs and wires since they were on the list and see if that helps.

 

do the cap n rotor..What brand fuel pump did ya use? for whatever reason these blazers eat aftermarkets. Unless its an ac delco or delphi you will indeed have problems.

 

Your 95 has CMFI with OBD1.5 engine controls, (not fully OBDII compliant). You mentioned that you checked for a loss of fuel pressure while the engine was running, not a bad idea but, GM does not publish any "engine running" specs for this engine so we need to check it with the engine off. Key in the RUN position, (don't start the engine), the fuel pump will be activated for ~2 seconds and then shut off. Check pressure while the pump is running. It must be 55psi to 61psi and it must remain above 50psi for at least 10 minutes after the pump shuts off. If it fails one or both parts of the test, it tells us there's a problem, it does not tell what the problem is, only that a problem exists and further testing is required to pinpoint the problem. Post your results.