Nicholbry

If I'm understanding correctly, you can simply remove the inner fuel pump and replace with a $50 strainer, thus your fuel delivery system would rely on the single, external pump (the one next to the external fuel filter). Correct?


If so, there are electrical connections to the pump. A few questions then:

1) What should you do with the wire(s) that formerly went to the internal pump now? Is it as simple as just taping them up out of the way?

2) Will it express a fault somehow with the car's brain if the electrical connections are not used?

3) Will this new arrangement put undue stress on the secondary pump causing it to fail more quickly?

4) If I replace the in-tank fuel pump with the strainer only, do I simply scavenge the 36mm nut (with a new gasket of course) from the old pump or is the strainer designed such that it mounts to the tank and outlet hose without a need for modification to properly seal?

5) So, Porsche designed our system with 2 pumps. Why?

6) Are there any negative aspects to replacing the in-tank pump with a strainer only?

7) Have any of you guys done this with success and what additional information might you give related to this swap?


Thanks guys for any help you can be. I smell strong fumes back there after having noticed the high-pitched "whine" as so many others have mentioned.

Nicholas

jeff spahn

bump for answer

John Speake

I fitted an 044 pump to a race car recently. We made our own harness. Pulled the existing pump harness back into the battery area and fitted the relay and fuse there, with new high current wiring back outside to the new 044 pump.

To answer some of your Q's...

1) Cut them off and/or tape them off. (Assuming you replace internal pump with strainer)
2) No
3) - 7) Others can answer better than me.

Cheburator

Answers in BOLD below

Nicholbry

Cheburator: Wow, thanks for such a complete (and timely) reply to all my questions. I do live in a rather warm climate with temps reaching 96°F (36°C) here in the summer months and relative humidity 100%. However, if other 928's (regardless of year and climate local) operate without any problems I may very well abandon the internal pump in favor of the less complicated (and cheaper) strainer.

Thanks too for the tip regarding the "thread insert". From what I've read, getting this system apart (nuts, etc.) can be a bear. Sounds like I will be investing in a set of decent flare wrenches to get the job done.

John S.: Thank you also for your quick reply

Nicholbry

I'm assuming you can do this with the factory external pump (928.608.104.03) also, and that this single-pump application that you guys are describing is not limited to the "044" pump only?

AO

Yes, should be fine with the factory pump.

Nicholbry

AWESOME! This is the reason I love Rennlist and why it's worth almost any money for a membership. Thank you guys for all your help. Fast too.

jpitman2

My car had an external pump only, and it ran in temps up to 120F for years. The wires that might have fed an internal pump were FACTORY taped up out of the way. Be sure to lube/antiseize the the threads of the filter into the tank, and ONLY tighten just enough to prevent leaks - not much more than hand tight!!! If your current internal pump is VERY hard to turn, do some lubricating of the thread area - if you over strain it, you risk spinning the thread insert in the plastic of the tank, and making the tank scrap....BTDT, although another guy managed to recover it.
jp 83 Euro S AT 52k

dprantl

If you are replacing the internal and external pump with a 044 external and a filter, do you really need to change the wiring? It was sufficient to run both the internal and external pump, so shouldn't it be fine for driving just the 044 pump by itself?

Dan
'91 928GT S/C 475hp/460lb.ft

Vilhuer

I have run 044 with original wiring. IIRR I connected also intank pump wires to external pump for some additional help.

cfc928gt

When the pumps failed on my '89 several years ago I called the pump manufacturer about how much pressure the internal pump generated and they said 5 psi. I don't have an opinion on running one or two but I thought I'd throw that tidbit of info out there in case it would help someone.

chewy8000

I have an 044 pump sitting in the box for when the SC goes on. Does my 81' have an internal pump? I know I can just look but I won't be at the shop for another week. Should I just replace it with the strainer when the time comes to drop the 044 in? Andrew great write up! You just saved me from having the fuel guts hanging out and the garage smelling like gas while I waited for the fittings I don't have.

Vilhuer

Yes, intank pump is useless piece of $#!t.

dprantl

+1

In fact, my S/C'ed car is now running on the stock pump and a filter instead of an in-tank pump. I have yet to install the 044 pump and am having no fuel delivery issues with 42lb injectors doing almost 75% duty cycle at 6,600RPM.

Dan
'91 928GT S/C 475hp/460lb.ft