Intermittant crank-no-start

[AKbigsub]

Here are the specs: '90 Chevrolet Suburban 5.7L TBI TH400 241C.
There is no detectable pattern as to when it won't start. When it acts up, I can hear the fuel pump pumping yet there is no fuel from the injectors. I was told of a way to check injector pulse with a digital multi meter, which I did. This tests to see if the DC voltage at the injector plug changes while cranking the starter. The voltage did change, indicating pulse. Although this will not tell if the pulse is proper. Thinking it was possibly a fuel pressure issue (ie pressure bleeding off through the fuel pump) I replaced the fuel pump (new AC Delco pump). This did not change the symptoms. Any ideas? Oh ya, once it starts, it runs great!

 

[dyeager535]

When you tested injector pulse, was it while it wouldn't start?

 

[AKbigsub]

Yes.

 

[dyeager535]

Agree then, fuel delivery problem.

ECM is seeing the engine cranking, injectors are commanded to fire, just no fuel pressure at the injector.

 

[AKbigsub]

Still need help. What,besides the fuel pump, would cause a fuel pressure problem? Is there a fuel pressure regulator on this year? I don't really want to take it to a shop (but may have to if I can't figure it out).

 

[Leper]

Pull the hose off of the fuel rail and put it in a secured jar. Go turn the key to on.DO NOT TRY TO START THE TRUCK AT THIS POINT. wait a sec or two and turn it off. Go see if there is gas in the jar.

 

[CustomChevy]

slight crack in the line causing pressure loss? line needs to refill before it will fire?



how long does it take to get it running again when you get the problem?

 

[Guss]

the pressure regulator is behind the injectors on the injector rack but before you do that i agree with LEPER take the fuel line off and see if any thing comes out also check the fuel filter.