Here are my photos that may help..

 

Have you tried the diaphragm kit from Heinrich in the sticky 760 hpfp diy thread above? People reported it works and I am waiting for my kit arrival and try to have my HPFP pumps rebuilt with it.

 

I have not. The seller on eBay sent me a 2nd set of diaphragms for free and the MagnaFuel some guys have praised upon. The diaphragms are pushing outward (to the top) which makes me feel like its an over pressure issue (its not as the FPR is working as tested). Looking for someone who has had similar issues.

Thanks

 

Hi, went the same route as you did and I can confirm the bad quality if those you tried. Tried two different set of diaphragms but they were blown in a couple of hours each as well. One of them was MagnaFuel, and the other was something on eBay. These should be banned from selling this crap.

Now I have a kit from Heinrich that is more promising, but I haven't really tried them out more than a couple of hour of driving before my n73 had the infamous valley pan leak. But I will update as soon as i have that sorted out.

I have a bad feeling that I end up with two new hpfp in the end, but we'll see.

 

I have no problem purchasing another set of diaphragms (if thats the failure and DO have two sets of pumps (dirty ones from China I got on ebay that I was told not to ship back) and the original I replaced all o-rings on that are blowing diaphragms in 20 minutes of driving. Heads up, I can start the car and idle for an hour + and they will not leak.

Question? Did your cheap diaphragms blow tin the same form mine did? (Blow out past the stainless ring?

Can you send me a link again or tag Heinrich. Happy to order ASAP.

Thanks,
Brian

 

Never use magnafuel diaphragms as they are trash. They are flat and not molded like the stock ones are and will fail as they are not meant to be installed for this type service. You are better off finding an original used junk yard pump. I have used a couple of those in the past with some success. Of course finding a diaphragm that will hold up to the extreme environment inside the pump can be a challenge. I have found a material a while back that does work and works well enough for tens of thousands of miles without leakage and still going. Still in testing. Yes there is another person in this forum that has sold his diaphragms to some people and they have claimed it works and others said they didn't work that long. How long they work is up for discussion. The ones I use are nothing like his. I don't want the liability as I am just giving my opinion of what to use and not use.

 

Appreciate your advise. I have one good green oem diaphragm.

Based on what you’re seeing in my photos, are they failing because of the mating surface or because of an over pressure / bad return issue?

I have 5 magna’s still sealed and was going to start testing again with the original return fuel filter vs the Mann jag one I used.

Appreciate your response.

 

In those photos you have posted, they do not look like OEM diaphragms to me. They look terrible with some sort of stretching failure in view. Yes they are fabric impregnated material which is used for strength, but they were clearly leaking before these pics. You have to know that the in tank fuel pump puts out 87 psi max which has nothing to do with the HPFP attenuators or diaphragms. That's the pressure to the pumps. HPFP are cam driven to increase the fuel rail pressure up to or can get as high 1000 PSI for the direct injection process. Mostly 800 is where it goes or a little less depending on driving conditions and hot shut down temps upon the fuel rail that is in a hot "V". Things you are doing i have been there and more. My vehicle idles so smooth I can balance a quarter on it''s side on top the the intake plenum and it won't fall till I remove it. Within reason of course. Since you have rebuilt the HPFP pumps and have never done that before you may have made an error. I don't mean to insult, but a complete tear down of the pumps without a guide to what size O"rings to use can be an issue. I have not done that myself, as I have not needed to. Sorry for the long post but your fiends original pumps may only need a good diaphragm to correct the issue since you bought tainted other ones. One thing I know is that a dried out used diaphragm and O'ring can be rejuvinated with a gasoline soak on the engine. Just throwing shit out there but it's true. Some people buy these cars and store them for months on end and when they start them again, all hell breaks loose. There meant to be driven.

 

They are not. The diaphragms are from ebay, seller is AAVIUS (heads up). I've used 3 different sets hoping it was the FPR that caused the issue but is not.

And yes, from my post fuel filter FPR test, I am getting approx 80psi so thats not my problem. I did rebuild a set of pumps and still have another set of pumps (one with a good diaphragm). Im going to clean them up with diesel, re-assemble and try one with the Magna diaphram (I have 5 new ones still).

I am having issues creating a new conversation to send @HeinrichG a message. Maybe its because my forum posts are low?

Thanks again for everyone's help! I'll try again next weekend when I get back from vacation. Cheers!

 

Since your reply indicates that they are not OEM disphragms, that is your issue. You see most 760 owners don't know that the factory diaphragms are a molded one. Most people think, well what does that mean? A molded diaphragm works like a piston in that little tiny space in the HPFP. OR, it it known as the attenuator, meaning to reduce the hard but high pressure impulse for every stroke of the piston inside the HPFP. A replacement diaphragm does not have to be molded but it has to assume that shape in order to work. That is what my diaphragm is. It molds itself to the inside of the pump chamber taking millions of pulses as you drive without failing to leak. It auto stretches to conform to it's environment inside the pump. Anyone with engineering knowledge has to know that.

 

billyjoe, Please share the material you are using so others can try it.

 

I ended up installing both Chinese provided oem pumps one with a good diaphragm and the other with a magna (that’s all I have available at this point). Both pumps are not leaking from the weep port which is great news however I am getting fuel (6oz a min) out of the return line that is pushing back into the evap solenoids into the manifold. I know this isn’t expected and I am suspecting the issue is the 3 way valve below the hood alarm pin. Thoughts / opinions?

 

You should replace that valve if you are getting fuel to thoses solenoids because that can cause rough running stalling when they are activated. You could always just disconnect the electrical connectors for those valves as they will not function and not allow fuel to be sucked into the air plenum. You will however trigger a code, but you will be allowed to drive the vehicle. I been there and done that. I purchased a used one from a junk yard as I could not find a new one at the time and solved my issue even when I re-connect the two solenoids.

 

I wanted to follow-up with my conclusion. I installed one of the "ebay china" sourced used OEM pumps that I cleaned up with an original good working diaphragm on bank 1 and my rebuilt pump w/ a single magna diaphragm on bank 2. Used an OEM fuel filter w/ FPR, blew out the return line and SUCCESS! approx 500 miles driving without any issues.

I informed the owner (my friend) the magna diaphragms are hit or miss so gave him another spare 4 and suggested to source another GOOD OEM pump. Thanks for all the feedback but another 760 back on the road. Cheers!