1992 Pontiac Grand Prix - 3.1L Fuel In Plenum?

[MickJagger]

Hey guys

A friend of mine asked me to post this up here, because he's at a loss.

He's working on a 92 Grand prix with the 3.1 and the bottom line of the issue is this:

Fuel in the intake plenum. Why would a half a coffee-cup of fuel be pouring out of the throttle body?

The plugs were soaked, he dried them off, tried it again, and they just got soaked again--
and the fuel is pouring out of the intake.

I say pressure regulator. One guy suspects the computer is shorting out sending fuel all the time, and another says the injectors are leaking. ALL the injectors leaking? I looked for TSB's but couldn't find anything relevant.

I thought we'd post it here, as a 92 Grand Prix isn't hardly worth $1000+ of labor trying to figure this out.. perhaps one of you came across something similar before?

[SANTA]

Hello! I spoke to our lead technician, this is what he suggests: Have you checked for spark? If none, most likey module or coil pack. OR Disconnect vacuum line from fuel pressure regulatr, cycle the key on and off 3-4 times, see if fuel shoots out of regulator, if it does it's the fuel pressure regulator. OR With key on, unplug wire fom injector, check for power, 1 side should have power, 1 shouldn't. If neither side have power, ground circuit is shorted t computer or thru computer. Good-Luck!!! Let us know what happens!!!

[steven kiser]

a bad pressure regulator will flood the intake. like said above if the diaphragm is leaking fuel will just pour out. it was very common in these. the regulator is fairly simple to replace. tell him not to let any debris fall in. the common wire on each injector will be power. the odd color ones will send negative impulses. the injector fires on negative. as a rule when the pcm fails on this car it usually shuts down the spark. if it's the way you've described it there is no realistic way stuck injectors could dump fuel into the intake without causing hydralock first. it would have to fill the cylinder before it backed up into the intake not to mention filling the exhaust. just a little tip here, if the car has been mmmmmmmmm cranked over and "flooded" numerous times look at it as "drowned" when it's finally repaired (regulator ) and started, keep a watch on the CAT'S they're going to cherry up. oh ya, when it finally starts gently clear it out. don't sit there and rev the engine. if there's the slightest exhaust leak it will suck air in and more than likely blow the muffler right off the car. the oil is probably gas soaked. if the regulator is bad and it gets replaced i strongly suggest the oil is drained and refilled before you start it. if there is a weak valve guide it may back fire and if by chance it gets a bit of flame past the bad guide the oil pan and and valve covers will look like jiffy pop that's popped. in my tenure of being a mechanic i've seen interiors set on fire by over heating cats, mufflers blown across bay floors, oil pans blown off, oil dip sticks shot out like muzzle loaders, valve covers blown off and plastic intakes look like a sledge hammer was taken to them. caution is the key word. don't let the gawkers look over the engine during initial crank. if they do and it explodes and god willing no one gets hurt please post it along with pictures. we all need a good laugh.......................................

[Tim Martin]

Very recently replaced fuel pressure regulator on one of these. Same situation. And, yes, they were occassional problem childs.