Fuel pump relocation due to hot start issue

[privatepang]

Hey guys,

Well i have a 75 911s and I'm having issues with hot start. Did a search and got some neat tips regarding fuel accumulator , check valve and using the fuel pressure gauge to assist in trouble shooting CIS.

Got my mechanic to sawp in another accumulator with one he had sitting around and it didn't fix the issue. Check valve was replaced and that didnt help. So doing mroe searching and I've read up regarding relocating the fuel pump to the front cross member from the rear.

I read in another post that a sponsor does sell a kit for this but I cant seem to find it. Can anyone point me to a link or name of the sponsor to look up? Did a search but couldnt find it.

Thanks!

[privatepang]

Also when people say sponsors, do they meant just pelicanparts catalog?

[E Sully]

Yes Wayne of Pelican Parts is the sponsor of this forum.

[privatepang]

Cant seem to find the kit... Are people just doing the relocation themselves ? See a lot of threads but not really how people went about doing it...I already have the fuel pump which i've been told works ok just need the lines re done...

[cmonref]

So. after a warm shutdown, the control pressure in the system drops below 20 psi in a matter of minutes and then approaches 0 in a few more minutes? This is after replacing the accumulator and testing the check valve? If so, then you might check the primary pressure adjustment on the fuel distributor head -- I found the O-ring inside the regulator to be leaking badly. That was the solution to MY warm start problem.

[E Sully]

I made my own bracket, and fuel lines were made with fittings from BAT. Maybe you can buy a fuel pump mount for a later car from the parts forum and install it on your front cross member?

[RWebb]

not sure if there is a kit

have you looked at the items in the PET?

[CharlieB]

I agree with Brian. Pull, inspect and clean the primary fuel pressure regulator on the fuel distributor head. Clean the regulator port with a q-tip and carb cleaner and reinstall if the o-rings are o. k.. Kits are available if o-rings are bad. Worth a try. Fixed my SC warm start problem!

[moneymanager]

Have never heard of a kit, I think most people do this themselves. Not difficult; I had to make an adapter to occupy the space at the rear where the pump was as two different sized lines were involved. Any good mechanic could do all that is required. But with a CIS car I'd check everything else before resorting to this as I doubt it will turn out to be the source of the problem.

[Walter_Middie]

with a CIS car I'd check everything else before resorting to this as I doubt it will turn out to be the source of the problem

I agree - the weather in Vancouver BC just isn't that warm. I live near Seattle and have a 1975 with the fuel pump in the stock location and have never had issues. I'm not saying that moving the pump is a bad thing, I just don't think it will fix the issue (unless the issue has to do with bad fuel lines that will be replaced).

[prebordao]

Originally Posted by CharlieB

I agree with Brian. Pull, inspect and clean the primary fuel pressure regulator on the fuel distributor head. Clean the regulator port with a q-tip and carb cleaner and reinstall if the o-rings are o. k.. Kits are available if o-rings are bad. Worth a try. Fixed my SC warm start problem!

I also have the problem frequently, and have gone through changing the accum and fp check valve without any success.
I hadn't heard yet of the FD pressure regulator being the problem... this means it could be leaking slowly ?

Also, finally I got to buy a pressure gauge so I can do some meaningful tests. What should be the pressure drop ? And I assume I should be measuring the system pressure ?

[ossiblue]

Someone, please clarify.

I never read from the OP that the residual pressures were tested--only that the mechanic replaced the accumulator with another one that had been "laying around." Brian did post some numbers but it's not clear those were from the OP's car--has something been deleted or is there another thread by the OP where this was discussed? Until the pressure tests are confirmed and followed up with specific tests to isolate the used accumulator and check valve, I would not dig into the fuel distributor nor move the fuel pump just yet.

[CharlieB]

I had the classic SC warm-up problem. Went through all the standard procedures, ie: Fuel pump, check valve, accumulator, filter, etc. Still my residual pressure dropped to zero in 30 seconds. Called my old-timer porsche mechanic who told me to pull and clean the primary fuel regulator in the top side of the FD. Never heard of that before anywhere! Took only a few minutes to pull it and clean the opening in the FD. All o-rings were good. The carb cleaner soaked q-tips came out dark red-brown til clean. Apparently if this thing is clogged or sticking or the 0-rings are shot it won't close properly and allows fuel and fuel pressure to be lost to quickly. Fuel gets dumped back thru return line to tank with resulting loss of system pressure when warm and engine has no fuel in the system upon warm start. Worth a try. Worked for me with little effort! Might work for you too!

[privatepang]

Thanks for all the feedback guys.

My mechanic did the fuel pressure tests and told me that the pressure does drop to zero once the car is turned off where its meant to hold for 40 minutes or so? I am a complete noob so didnt want to mess around with the CIS without knowing what I was doing.

New fuel lines were installed 2 months ago as well.

Car was running rich so mechanic made a mod to the WUR and did an adjustment to get it to pass smog. He did mention that when he did the mod that evening, the pressure dropped the day after slightly so he had to re adjust it? Meaning the WUR may need to be replaced? Pretty sure it was replaced by the PO so dont really want to resort to that if possible.

Fuel accumulator that was swapped temporarily was from his working 911 so he said that defitnely isn't the issue.

I double checked with the mechanic regarding the check valve and he said that my pump doesnt have one as its not a stock porsche pump? Said he'd have to look into it more if I wanted him to work it out.

Main reason for bringing it there was to get it to pass smog which he did. Saving up for more work to be done so was trying to do as much research here as possible. Thanks for all the replies guys. Really helps and slowly building up my knowledge about the car through all the useful info on these forums!

[privatepang]

Originally Posted by CharlieB

I had the classic SC warm-up problem. Went through all the standard procedures, ie: Fuel pump, check valve, accumulator, filter, etc. Still my residual pressure dropped to zero in 30 seconds. Called my old-timer porsche mechanic who told me to pull and clean the primary fuel regulator in the top side of the FD. Never heard of that before anywhere! Took only a few minutes to pull it and clean the opening in the FD. All o-rings were good. The carb cleaner soaked q-tips came out dark red-brown til clean. Apparently if this thing is clogged or sticking or the 0-rings are shot it won't close properly and allows fuel and fuel pressure to be lost to quickly. Fuel gets dumped back thru return line to tank with resulting loss of system pressure when warm and engine has no fuel in the system upon warm start. Worth a try. Worked for me with little effort! Might work for you too!

Ok this sounds easy enough. Just worried I might break something! LOL. Thanks for the tip

[Joe Bob]

Moving the fuel pump is not the answer......dropping fuel pressure is related to the fixes above. You just need to futz around 'till ya find it.

Good luck.

[privatepang]

Sorry to ask a silly question. But exactly where are you cleaning using the qtips?



Read that you need to turn the engine over to Z1 before removing the FD? Or did you just take the cap off when it was still on the car and do the cleaning?

[prebordao]

Oops !
not that distributor !

The FD is where the injector lines are coming from.

[privatepang]

Ah woops. Ok new diagram then.

[IMG]http://www.***********.com/porsche-parts/928-78-82/main/107-00.jpg[/IMG]

[privatepang]

So place to use the q tips are the 8 holes at the top of the FD right? So just take the top off and just make sure there arent any restrictions?