Back firing and dying

[behodges]

I have a 94 gmc c1500 with the 5.7l.
It has ran like a top since I bought it off my grandfather. It has 170k original miles on it. All of a sudden one day driving down the interstate it stated back firing and then died I would start right back up but when I have it gas it would hesitate back fire and then die. Limped it home with it doing this several times. Got about a mile from my house stepped on the gas and it was fine. Check the flash codes and said iac issue. Replaced the iac and seemed fine next time I took it for a longer drive it did it again. Put a new iac in. I have replaced the tps, egr I did find a vacuum hose that went to the tb fixed it still doing it. I can't find any other people that can help me figure this out. I was thinking maybe a failing fuel pump but don't want to spend the$$ and time unless it's going to fix it.

 

[Orpedcrow]

I’m sure someone can comment on the specs, but you can rent a fuel pressure checker kit and verify a bad fuel pump before spending the money on a pump. Sounds like a pump though

 

[PlayingWithTBI]

I’m sure someone can comment on the specs, but you can rent a fuel pressure checker kit and verify a bad fuel pump before spending the money on a pump

^^^This is the 1st place I'd look, your pressure s/b 9 - 13 PSI (according to GM) but, I'd prefer 11+

Then I'd go look at the ICM and pickup coil in the distributor - all known issues.

 

[behodges]

Is it common for it to only do it after it's warmed up. It usually is about 20 to 30 minutes either idling or driving. When I test it should I do it when I first start it and then after it's warm? Make sure it's acting up type of thing

 

[Schurkey]

Acts-up when fully-warm, test it when fully-warm. Getting hard to find TBI-compatible fuel pressure testers. Most have gauges that go to 100 psi, you need one that shows ~15 psi accurately. And you'll need a TBI fuel pressure adapter, too. There's at least two kinds--one goes on in place of your fuel filter, the other screws to the back of the throttle body at the fuel inlet. Either one works, some vehicles (Vans) don't have clearance for the one at the throttle body.

How old are the usual "tune-up" items--spark plugs, plug wires, cap, rotor, fuel and air filters, PCV system inspection, EGR system inspection, etc.?

 

[1990Z71Swede]

Our truck did this the other day.

Backfired and stalled, restarted an ran ok again for a couple of kilometers, stalled again, restarted, did not run well at all but was able to creep home the last 500 meters where it stalled yet again. Would not rew, just puffing black smoke and missing pretty bad at idle.

Cap and Rotor looked.. not so good, cap was worse. (pic in another thread)
Replaced with new AC delco parts, Runs fine now, a tiny bit peppier than before even.

 

[behodges]

Acts-up when fully-warm, test it when fully-warm. Getting hard to find TBI-compatible fuel pressure testers. Most have gauges that go to 100 psi, you need one that shows ~15 psi accurately. And you'll need a TBI fuel pressure adapter, too. There's at least two kinds--one goes on in place of your fuel filter, the other screws to the back of the throttle body at the fuel inlet. Either one works, some vehicles (Vans) don't have clearance for the one at the throttle body.

How old are the usual "tune-up" items--spark plugs, plug wires, cap, rotor, fuel and air filters, PCV system inspection, EGR system inspection, etc.?

New plugs and wires last year new egr a few weeks ago tps iac new air filter last year I don't drive it all the time. Got a new fuel filter just haven't changed it yet. What do I do to inspect the pcv and egr system?

 

[behodges]

Just wanted to give an update with my issues so it can maybe help others. Changed the fuel filter and the ICM. Yesterday and seemed to fix the problem had to wait until today for the new cap and rotor. Let it warm up for 25 minutes then drove it for another 20 minutes and never acted up so I think the main problem was THE ICM. attached are pictures of the old parts don't