: 1997 deville hard start warm engine

01-17-09, 02:09 PM
Northstar cold starts very well. All subsequent warm starts the engine cranks for a long time and when it does fire it stumbles like the fuel flow is not correct either too much or not enough.

01-17-09, 05:47 PM
Pull codes: http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/53635-got-codes-look-here.html

Check the fuel pressure reguator. Pull the vacuum hose off the top. Gas present = bad FPR. FPR is located on the driver's rear of the intake manifold, underneath the beauty cover.

01-17-09, 06:53 PM
I'd almost bet on the FPR.

01-19-09, 04:30 PM
Thanks.. The fpr is made into thr fuel rail on the engine. It was done as the result of a service bulletin.. If the FPR is bad do you have to peplace the entire fuel rail??

01-19-09, 04:35 PM
Do i check vaccum with engine running or off?

01-19-09, 06:24 PM
No the FPR is removed from the rail and replaced separately. Pull the vacuum line while it is idling and look for fuel leaking from the nipple. If it is leaking, replace it, but be sure to bleed off fuel pressure before removing it.

01-19-09, 07:00 PM
Why does a leaking FPR only cause a problem for warm engine starts?

01-19-09, 07:14 PM
Because the leak is unmetered fuel sucked into the intake causing a rich condition. Much like trying to start a hot carbureted engine with the choke engaged.

01-20-09, 10:12 PM
i had the same problem you're describing. replace the fpr. change it even if you smell gas from the vacuum port.

01-21-09, 02:08 PM
I had the same problem you're describing. the FPr was leaking gas into the intake hose, I replaced the fpr, and have not had the problem since - for months.