tomek

I have a question regarding fuel pressure regulators.

Does their quality gradually deteriorate or do they work fine until one moment they die?

The reason I'm asking is because I have 2 audi v8's. 1 running and 1 parts car. Iv been having hot+cold start problems with my running one and thought I would take the FPR off the parts one and try it on the running one. It starts significantly better, but not perfect yet. And the new FPR I put on is not brand new, and looks pretty old. So I'm wondering if my hot+cold start issue will disappear if I put in a completly brand new FPR?


So, do FPR's deteroirate over time, or do they work fine until they meet a sudden death?

Thanks,

Tomek.

V8QinNJ

The diaphram is under vacuum on one side and fuel on the other, with a rubber slice between them..they start to fail as soon as they are installed IMO. Which may be a number of years before it happens..

A FPR.. IME.. will not generate your hot/cold start issues, drivability yes. if its bad, the engine vacuum will suck fuel into the engine via the hose causing the engine to hydrolock (from fuel)..that is why everyone preaches if you didn't change it, to do it...it's cheap insurance.

Chances are your hot/cold start issues are in the RPM / CPS sensors..but tats just a wild guess. if you can blink out any codes, that'll give you a starting point.

HTH...

Scott '90 V8Q x2

MrGoodbytes

I'm sorry Scott, but...

"they start to fail as soon as they are installed IMO"

That's hillarious. I can't think of how many things in life follow that exact forumla.

Like buying a car. Drive it off the lot and take at least $5k off it's worth.

tomek

Well the RPM gauge on the dash works a-ok. But I suppose there could be a seperate sensor for the comptuer as well as for the dash?

Where are the CPS / RPM sensors located in the 3.6 V8? Are they difficult to access?

Also I should mention, this did help. Not fully, but I used to have to (not always tho, depending on how long it was sitting) crank the engine for 5-10 secs. Now its more like 2-5secs. I'll order a new FPR this weekend.

Thanks,

Tomek.

MrGoodbytes

The RPM and Speed sensor are located between the left bank of the engine and the left headers. Car manufac. tend to put these in impossible places.

If, during cranking, the tach needle bounces, the sensors are most likely okay. FROM MY EXPERIENCE, these sensors tend to be binary: they work or they don't. Although others my have other issues.

I believe I'm having some of the same issues you are and I'm getting my FPR next week. I'll keep you apprised with the results I get.

tomek

thanks i'd appreciate that, ill order mine tommorow but im in canada ordering from down south so it'll probably be next weekend.

from what i remember, altho ill double check, the rpm needle does bounce when im crankin it.

anyways, let me know how it goes and ill do the same.

thanks,

tomek.

V8QinNJ

Scott (S)-

The RPM and CPS sensors the bit about them being binary.. I disagree. while I generally agree that an electronic compoent will either work or not work, in an of itself, but a sensor that has to change output is a completely different animal. may work at the bottom of the range then not at the middle or top of range, that idea.

There's a page in the Twiki on them. and what you get is a when HOT, no restart.

<a href="http://www.audifans.com/twiki/bin/view/Audi/NoStartV8">Twiki Page</A>

Tomek's cold start issue might be related but there's a pretty good guess that this will be the hot start side of it.

'da other Scott