Truck having trouble starting

[Obssean]

I have a 1998 Gmc K3500 with the 454(7.4) big block. For some reason that seems to be at random the truck will not start without me pressing on the pedal a few times. If I don’t give it gas it will just sit there and crank. Not a huge deal i’m just curious why this is happening and can’t find any info on it. Any ideas?

 

[Schurkey]

What is the fuel pressure when the truck cranks but won't start?

Connect a scan tool, look at the RPM reading when it's cranking but won't start. While you're in there, look at all the other sensor and output signals--coolant temperature, MAP, cam sensor retard/offset, fuel trims, etc. to see if they're within normal range.

Does the truck crank at a normal speed? Battery isn't discharged, starter works properly?

 

[Supercharged111]

Injectors and/or FPR leaking. Those motors are notorious for it. Mine was that way when I bought it too.

 

[Obssean]

What is the fuel pressure when the truck cranks but won't start?

Connect a scan tool, look at the RPM reading when it's cranking but won't start. While you're in there, look at all the other sensor and output signals--coolant temperature, MAP, cam sensor retard/offset, fuel trims, etc. to see if they're within normal range.

Does the truck crank at a normal speed? Battery isn't discharged, starter works properly?

I don’t have a scan tool that can read any of that stuff. Any ideas on what a good one would be? Batteries are fine and the starter is brand new. I put it on last week and it didn’t help the problem.

 

[Schurkey]

I don’t have a scan tool that can read any of that stuff. Any ideas on what a good one would be?

Mine is a Snap-On MTG2500. About the same as the more-common MT2500. I have software to use with 1980 1/2--2006 model year domestic vehicles.

If I were buying one now, I'd get something newer; Snap-On hasn't supported the '2500 series since 2008.

Some guys like the laptop-computer-based scan programs, but I've never used one.

 

[jjester6000]

I have a 1998 Gmc K3500 with the 454(7.4) big block. For some reason that seems to be at random the truck will not start without me pressing on the pedal a few times. If I don’t give it gas it will just sit there and crank. Not a huge deal i’m just curious why this is happening and can’t find any info on it. Any ideas?

Stupid question, it it carbureted? Maybe someone swapped in an older model 454 in you're truck, and that is normal starter procedure for a carbureted engine.

 

[Obssean]

Stupid question, it it carbureted? Maybe someone swapped in an older model 454 in you're truck, and that is normal starter procedure for a carbureted engine.

It’s not carbureted. It’s the original mpfi motor

 

[stutaeng]

Probably leaky FPR flooding the engine after shutoff...if I had to guess.

 

[Nad_Yvalhosert]

Sounds like the IAC passages are plugged, not getting enough air to run. Opening up the throttle gives it air.
Pull out the IAC, clean thoroughly, reinstall and perform an IAC relearn.

 

[Obssean]

Probably leaky FPR flooding the engine after shutoff...if I had to guess.

Is there a good way to check that?