Bill Ball

I had no problem replacing the intank pump with the gas tank in position. Fortunately, I had no sediment in the bottom of the tank, so it was a very quick job.

RyanPerrella

Keith,

You mention you were going to replace the rubber hose from the intake pump which is usually destroyed anyway. I guess thats possible, its just a small piece of hose attached with 2 clamps, sounds like a good idea to me. I recall paying $120 ish for the intank pump when i replaced mine.

As for the main pump, you can get them from Porsche or 928INTL or whatever, but i would buy new. Of course it really is fairly easy to get to so you can just throw just about anything in there to get the car running and replace when the new one comes in.

If this happened to me again, i would simply replace with the "044" pump which is supposed to flow more fuel per hour then the stock porsche unit. I dont think i would SC a car at this point, but i would look to larger displacement or trying to get more Power such as what the SF bay guys are doing. I imagine at some point once they move to 30# injectors the fuel pump will become a limiting factor.

Just thinking aloud.

Charley B

I know it has been discussed here a few times, but has anyone eliminated the in tank pump and went with the "044" pump on a GTS as a means to combat detonation? And if so what were the results?

IcemanG17

Keith
i still have my "high resistance" pump......I'd imagine some new brushes in the motor would fix it...but thats beyond my capabilty.....its yours if you want it...free of course....

Mrmerlin

you might try running some marvel mystery oil in the pump try it both ways, the marvel oil is less flammable than most other solvents, and with the pump leads close to the output it could catch fire with a sparking lead

SharkSkin

Keith, if you're not driving much maybe you had some water sitting in the pump. Maybe some ethanol or other cocktail to get the water in suspension, then run the tank down till the light comes on and fill it up.

BTW, if the pump is acting up, it's time to replace it. You may be able to get that one working but its days are numbered. They are not rebuildable by mere mortals...

Randy V

Charley - please clarify.

When I see 'fuel pump', 'GTS' and 'combat detonation' I get interested.

AO

Keith-

Just coming out of my hole for some air here. If you need a pump, I have my old GT pump that was frozen like yours. After I pulled it, I tried switching the polarity (reversing the motor back and forth) several time and it eventually worked again. I ended up replacing it with the "044" pump. But I still have it as a spare and it's yours if you want it. No guarantee it will work. Try reversing it a bit more and see if that takes care of it.

Charley-
I kept the in-tank pump, but in hind-sight, I probably could have eliminated it. The "044" pump will not in and of itself eliminate detonation as the fuel pressure regulator will continue to meter the amount of fuel delivered. That said, if you were to add an adjustable pressure regulator and turn up the pressure a bit, you could potentially increase the AFR to enrich the mixture to the point where you would have less detonation. But unless you're running forced induction, you really should not need this - plus this approach is a band-aid approach to relieve knock at best. The stock pump is good to about 450RWHP.

If you have detonation issues, you most likely are running the wrong grade of fuel, need new plugs, or have some other mechanical issue.

Tony

Thank you andrew, now back in yer hole..did the Lamma seen his shadow yet??.
Good to see you!

Looks like you found the problem Keith!..good

928ntslow

Thanks guys. I am actively looking for a working pump at the moment. Let's see when I get it, if that cures the problem. (expect it should)

Randy V

Good luck, Keith!

Hey, can you tell me again which spark plugs you are running in the GTS?

If I recall, you had previously indicated that switching to those plugs reduced/eliminated pinging issues.

Thanks!

Jim bailey - 928 International

The "leak test" per the tech spec books is 20 minutes. So that was how long Porsche expected the fuel system to retain 3 bar of pressure (S-4 >) . So if a fuel pump DIES fails to turn on a restart after more than 20 minutes most often there will be no fuel pressure in the system and the car is not going to try to start, cough , sputter or anything else. The difference between 40 lbs of fuel pressure and zero inside metal fuel lines is a few drops of gasoline...the lack of compressibility of most liquids is why we use brake fluid in our brakes.

928ntslow

Randy, IIRC they are Bosch single electrode copper plugs.

Charley B

Well I think I solved the issue. After having a BG sevice performed and sanitizing the heads, detonation improved about 20%. After replacing the in tank pump (Yes, hose was shot) detonation improved another 20%. Taking a suggestion from Paul M. I replaced the fuel filter yesterday, and Wala, the detonation is 99% gone. With 91 octane fuel, that may be as good as it gets. It also cured a hesitation I was getting between 5500 and 6500 rpm's.

Randy V

Would you happen to have the identification numbers?