Replaced mine. Learned it was damaged after driving. Looks like a cookie cutter went around the orange/tan gasket part and cut it. Possibly ruptured? What could cause this. Need to repalce but not doing it until I understand why it failed.

Is it the OEM diaphragm?

Regardless of age, they are under pressure. By their very nature, they are a boundary between 2 different things - in this case, air and fuel. And the fuel is at 50+ PSI. I would get tired, too. Over time, the piece stretches and simply gives up. Remember, fuel is toxic and attacks materials, even ones resistant aren't resistant forever.

There is nothing more to understand. Be thankful you can get a new one!

I had my last replacement fail in less than 2 years. No idea why. Ruptured where the rubber connects to the middle spring part.

Matthew

Mine was about 2 months old. The rubber part was just cut by the regulator for some reason. Do you tuck the rubber piece all the way under the regulator or let it poke out a little bit?

As far as the reason the diaphram failed, any movong part has a fatigue limit. Your's hit the number.

And no, do not tuck the "rubber" under the cap.
Lube the diaphram edge around the holes with a light coat of lubricant. This prevents the screws from grabbing the rubber and pulling it off center.

Check the fuel pressure/ bleed down prior to installing plenum, just in case there is a problem.

I changed mine yesterday due to the pressure not holding, but my diaphram was good. It was the disc seat on the diaphram not sealing to the regulator body. Less than 2 years old, BWD brand.

Joel

TPIS.com has the best price I have found on a good diaphram. If your car is between 85-92 the price is $39.95, here's a link..WW

http://tpis.com/parts/view/15

I just got off the phone with TPIS. Very polite and quick. Got me a new FPR diaphram for 40.00 dollars. I have the Adjustable fuel pressuse regulator they sell also. Had that on when the first one ruptured. Let me say, the AFPR is very nice. It's much cleaner and sturdier than the factory one. It's good steel and not some cheap burned up POS from the factory. Then again, mine is 25 years old! When my mechanic was adjusting and swapping it out, he said it was a very worthwhile mod even for stock because you can get it right on the money. He said it wont make much difference for stock but anything is better than nothing. He said for my mild mods, it will help and for a modded motor, required! Said it can drastically help MPG and a few ponies for the big strokers. Thank you for all the help guys! Jon sent me my new injectors. Over nighted them to me

Let me say, FIC is the ONLY place I will ever shop at for injectors and the ONLY place I will recomend.

I got the 24 lb Bosch III. I watched the video and it caught my attention automatically. Top notch customer service even late at night. Had my chip tuned by pcmforless.com They were fast and they got my tune right on the money without even doing a dyno. They are 25 minutes from my house so I might get it dyno tuned one day......Maybe.....

Again guys, thank you for all your help and if I can ever help someone else, please feel free to ask. This car has truely helped me learn things about cars and motors I could never imagine.

When we get angry at our cars we keep at it and we learn. Yes, they are unreliable and expensive but there is no price on education and thats something no one can take from you.

Look at Bogus. he knows a ton about our vettes and hell, he can rebuild a motor with a blindfold on lol. I think he will say that his C4s have taught him alot yes? Damn good teachers if I do say so myself.

Have a good rest of the week guys. Be safe!