Vortec 454 - Slow Starting

[dhcomp]

Ok, I'll leave the brake issues and other crap about my new rig in the other threads.

99 Vortec 454, 165k on the clock.

Turns over quick, but takes a bit to fire. Thinking its one of 3 things:

- Fuel Pump relay - Possibly starting on backup through oil pressure sending unit?

- Fuel Pressure Regulator - will disconnect vac line to check for seepage

-Leaky injector - what is the proper diagnostic to check for fuel pressure drop when motor is shut off? I have a gauge.

Any Comments regarding diagnosis?

Thanks!

 

[y5mgisi]

Can you hear the fuel pump running? With engine not running and with.

 

[dhcomp]

Can you hear the fuel pump running? With engine not running and with.

Definitely with the engine running i can. Going to double check it primes every time.

Also going to swap fuel filters, caues i'm sure this one is trashed.

 

[y5mgisi]

Good idea. But was just supposing as a way of confirming your bad relay idea, if you cant hear it with just key on but engine not running, but you can with the engine running, thaat would pretty well confirm your idea i think.

 

[COCHEV]

is it every time you start it or hot starts. I know mine is funny with hot starts some times, which i hear is common with these...

 

[dhcomp]

Mine... all the time.

 

[COCHEV]

just for reference, here is a rediculously long thread on rigs with our drivetrain...

http://www.fullsizechevy.com/forum/...intenance/213662-96-99-454-vortec-owners.html

and they added a bbc sub forum

http://www.fullsizechevy.com/forum/general-discussion/performance/big-blocks/

 

[bigblock72]

On just about every one of the vortec 7.4s that I see they end up needing a set of injectors and a fuel pressure regulator. There are a lot of places that sell rebuilt injectors for these and the prices are fairly reasonable (240ish a set) so it isn't worth replacing them one at a time. The regulator on these is either new or it's leaking so replace it while everything is apart to save yourself some grief. The good news is it's a pretty easy job and once you do the job you shouldn't have any problems for quite a while.