Fuel Pressure Damper

[gniknave]

I've been having this continuous problem with stalling, bucking, and fuel smells when I'm slowing down. When starting the car I get a fluctuating idle between 1000-1700 RPM, this lasts for a few seconds before settling to a strict 1000 RPM. I let the car warm up before I drive it for about 10 minutes or until it reaches "normal" operating temperature. Once warm, the idl settles to 700 RPM. When I'm coming to a stop, I must come to a very slow stop or the car will stall.

*Fuel pump replaced two weeks ago

I had a mechanic check for this problem a few months ago after smelling fuel in the cabin. We noticed some dripping coming from behind the plenum just under and to the left of the AAC (if you're in front of the engine). Looks like the Fuel Pressure Damper was the culprit. I didn't have it fixed back then because he didn't seem to feel comfortable doing the job - I don't want anybody that doesn't look comfortable touching my car.

I did a search and saw nothing about this subject. I'm hoping somebody (Dennis?) has some knowledge about this part as far as how to replace it as DIY. The part itself isn't expensive, and it looks like it MAY be possible to do without removing the plenum. I'm sure someone out there is thinking my problem may be a leaky injector or FPCU for the stalling problem, but I'd like to take care of this problem first and then go further if the problem persists.

[Q451990]

The damper is a very rare failure item - I'd be more suspicious of the hoses that tend to leak when it gets cold. You might try tightening the hose clamps to see if that helps...

Heath

[gniknave]

I figured it was pretty rare since I couldn't find it in search. But when I look at the damper, it looks like it's wet from fuel.

I just noticed a small pool of what looks (and smells) like fuel in the valley just furthest to the back of the engine. This is leading me to believe there's more than one leak?

Would a leaking fuel hose cause the stalling that I'm complaining about?

[DAEDALUS]

Seems unlikely, like it would have to be a pretty substantial leak to cause such severe drivability problems. Just my .02.

[DougQ45]

I had a 2 leaky hose clamps in the same area, and I believe it was the fuel pressure regulator hoses. It showed up when cold. After the car warmed up, the metal expanded and the leak went away. Try looking with a flashlight to find the leaks while someone starts the car first thing in AM or when cold. The clamps are hard to get to.

[gniknave]

Yeah I actually saw the dripping while the car was running but it's so tight squeezed back there that you can't really tell where the leak is coming from.

(1)DAEDALUS, since you say a fuel hose leak shouldn't cause a drivability broblem, what do you suggest would cause the symtoms I'm having? I'm thinking FPCU since I may have gone a wee bit too long before replacing the fuel pump, (2)but would that cause a fluctuating idle?

[DAEDALUS]

A bad FPCU could cause a fluctuating idle from what I've read here. It's already suspect; that would be the second thing I investigate, after spending a few minutes making sure it isn't the MAF connection. A fuel injection gauge can be had for about $35 or less, and that might confirm the problem, or you can go in for an hour's diagnosis in a (reputable) shop for a more certain answer. If you're going to pay for diagnosis, make sure they have/use a Consult.

[gniknave]

Good advice. I cleaned the Throttle Body, MAF + Connectors about 3 weeks ago. That resolved a rough idle I had but stalling continued. I'm not ready to dish out more dough for diagnostic at this time of year. I'll probably go for the gauge and see what I come up with. Thanks!

[elwesso]

A bad FPCU could cause a fluctuating idle from what I've read here. It's already suspect; that would be the second thing I investigate, after spending a few minutes making sure it isn't the MAF connection. A fuel injection gauge can be had for about $35 or less, and that might confirm the problem, or you can go in for an hour's diagnosis in a (reputable) shop for a more certain answer. If you're going to pay for diagnosis, make sure they have/use a Consult.

Hmm, ill have to swap mine in

[Jesda]

My symptoms:Stalling at stoplightsFluctuating idleFuel smell in cabinOccasional bucking on the interstate

Cause: Bad MAFSolution: $50 used MAF from car-part.com

[gniknave]

Jesda, did you try a MAF cleaning before actually swapping it? At the rate I'm going I might as well just swap the MAF and the FPCU and pray!

[Jesda]

The MAF cleaning the first time around made a noticeable difference because it had never been cleaned, but the problem came right back.

A bad FPCU usually causes it to stall at -any- speed. And if you remove it and look inside, you can almost always see physical damage if it actually is failing (though sometimes you cant).

[96Qowner]

I had many of your same symptoms, jesda. I replaced the fuel pump first, which didn't solve anything (glad I did though- it had 157,000 miles on it). Replaced the fuel filter and cleaned the MAF at the same time, and the symptoms haven't returned, but so far no sign of any trouble with the FPCM.

gniknave, mine was perfectly progressive, starting with an occasional cough at highway speed, and then later, a couple stalls when I'd completely let off the gas for exits ramps, nothing serious. Then after a few thousand more miles, more severe coughing, which then progressed to bucking and jerking. I never noticed a gas smell, but that might be because I still have a valve cover leak (waiting until I can justify a full plenum job).

Several posters had similar symptoms, and I read through all the past posts I could find. Your symptoms conform to problems with the MAF, as well as fuel delivery problems involving the fuel pump, filter, and FPCM. My experience teaches me that you should isolate the MAF first. If that's working properly, check the FPCM (which can be isolated by a jumper to ground as per jesda and others).

I don't know as much as most here, but I've been through the diagnosis of this one, step by step. 'Course, yours may be sumpin different.

[gniknave]

Weird thing I noticed this morning when I put gas in my car. I started it up, and the idle fluctuated (always does when I put gas in) and then I felt a rough idle and the RPM died down to 500. I immediatley thought it was the MAF connector because last night I took a picture under my engine for another thread and the flashlight was propped up against the connector. Later on when I was driving (same trip) the check engine light came on.

When I got to work, I left the car running and wiggled the MAF connector and immediately heard the engine settle to a more comfortable idle (around 700rpm). Then I shut the car off, restarted, and no check engine light, no rough idle.

Is there an easy procedure for replacing the MAF connectors? I'd like to nip this one in the bud and just do it if it's not too much trouble.

Looks like it'll be a busy Christmas Eve for me, I'll be replacing:

- Upper & Lower Radiator Hose, drain plug & gasket - MAF Sensor - FPCU - MAF Connector???

96Qowner, I keep going back and forth on determining if my problem(s) are MAF or FPCU related. I figure just do both and be REALLY PISSED if my problem doesn't go away.

[96Qowner]

I think you can buy a replacement connector from Joe.

[Q451990]

I assume you've tried tightening the connector pins? I've done this with a dental pick, but a bent paper clip should do it... The pins are shaped in a rectangle with a joint in the middle of one longer side - I just push the joint inward a bit with the dental pick.

Heath

[pito11213]

I agree with Heath try the connector pins and some dielectric grease first.

[gniknave]

pito/Heath, I tried tightening the connector pins and they're tight as a Richard Simmons spandex suit. The part I wiggled was actually the back portion of the connector (the black part before the wires).

[DougQ45]

Make sure the wires are pushed all the way into the connector, or are not out of alignment. The rubber sheath covering the plug covers too much.