Signs of a bad fuel pump?

[cmcfaul]

My car won't rev past 5500 RPM's. It pulls hard all the way there then dies. Thought it might be the rev limiter but that should kick in at 7300.

If I keep my foot to the floor it dies down to 4000 and runs rough. When I let the RPM's come down again dirve normally for a bit, it runs fine until I step on it and the process repeats it's self.

Idle and timing are perfect as I set them yesterday.

Are these symptoms indicative of a weak fuel pump?

Thanks

Chris

73 911 E MFI

[Steve@Rennsport]

Chris,

Sounds like a fuel delivery issue.

This can be caused by:

1) Partially clogged fuel filter (never assume anything)

2) Partially clogged filter screens at the outlets/returns on the fuel tank

3) Failing pump

MFI electric pumps are NOT cheap to I'd thoroughly investigate everything else and test the pump's volume before buying a new one.

[T77911S]

if that does not do it, check the advance on the timing.

[Fritz Peyerl]

Chris, I had this problem on my last seaso drive. Had to be brought home on a flatbed.
I found that my pump runs for 5 minutes and than looses pressure.
I installed a gage in the line towards the MFI pump and any time I lost power, the pressure dropped to 4 PSI it should be 14 PSI
I found a used replacement pump. I think the bypass valve kept sticking.
Now I have to wait till the snow is gone and than I can test the new /used pump.
I drained the tank checkt the strainer in the tank, The fuel lines where replace one year ago.


Fritz

[Flieger]

It does sound like the fuel pump. I feel for you. The Bosch 001 pumps are very expensive- I know.

[Eddyvdw]

You can simply test the fuel pump.
Pressure 1 bar, delivery 800-1000cc / 60sec (if I remember correctly).
Just take the return line at the fuel filter.
Ed

[cmcfaul]

The problem only happens when the car is fully warmed up. I have no screen in the gas tank. The fuel filter is huge and replaced about 6 years ago (so maybe but doubtful).

I know the fuel pumps are expensive. I think Bosh started making them again and the price has come down to "typically expensive".

Another reason I think it might be the fuel pump is that I changed the spark plugs after a couple hundred miles and two came out like new the others were expectantly dirty. I suspect I am not getting enough fuel pressure.

I dumped in a can of injector cleaner and it helped a bit but still suspect the electric pump.

Nothing last forever (38 years). If the pump is not bad I can expect to replace it some time down the road. Think I will replace it now regardless. Don't want to be far from home when it decides to completely die.

Chris

73 911 E

[RoninLB]

when my pump was going south it made more and more noise over the course of a few thousand miles

when flow became bad enough it wouldn't allow engine to rev under load and engine started breaking up

from my experience and what i could surmise these Bosch pumps have one foot in the grave and the other on a banana peel after 100k miles

[cmcfaul]

my thoughts exactly. It has lived a good life, 150k miles / 38 years. A new pump (not bebuilt) is $255.

Chris

[Eddyvdw]

I'm quite interested in one of those new pumps.
Where did you find it?

Ed

[cmcfaul]

Zimms makes a compatible pump. The few people I have talked to say it works perfectly. Porsche / Bosh has started producing new OEM ones as well. There was a thread here on them a couple months ago.

Chris
73 911 E

[Flieger]

The new "Bosch" ones are made in China. I would stick with the real German Bosch units from a good rebuilder.

Mine worked fine and I drove into the garage one day, then the next weekend went to start it and no go. There was no fuel pump noise. I think I tapped on it or just waited a day and then it started. It only got me a few miles though, with the engine breaking worse and worse. Got a flatbed home. I figured it had stopped at a bad spot on the commutator but the thing was so old that the brushes had worn all the way through the commutator into the steel shaft and was therefore un-rebuildable.

I got a recently rebuilt one from the Pelican classifieds. The seller got it from Zimms, I think, and had used it for a few hundred miles until he switched to carbs for other reasons. I avoided a core charge that way.

The rebuilt one works great.

[cmcfaul]

Any feedback on the ones made in China?

[Flieger]

Everyone on the Early 911S Registry is too scared to find out!

[Flieger]

Bosch 0580 MFI Fuel Pump Available from Porsche Classic

[mtndawg]

I just put a pump in my '82, it's a rebuild from Fuel Injection Corp in Livermore, Ca. I've bought some other things from them too. Very good prices and good work. They sell the new pumps from China too.

[RoninLB]

I once had Bosch tech on the phone and he said the tolerances are very very tight and not to rebuild the fuel pumps or fuel distributors

I think if I had rebuild parts for the pump I'd test the output at 75 pounds and see what happens after rebuilding

anyone know where to get rebuild parts ?

[Flieger]

The part they rebuild is the motor part. On my original, the pump section is still fine. You rarely hear of a leak in the pump section itself- the old German Bosch quality. The pump section did indeed look precision fit when I took a look in there. Where they wear is in the brushes and commutator of the electric motor section. Those are wear items like a clutch or brake pads.

An '82 does not have MFI. We are talking about the MFI's electric fuel pump.

[RoninLB]

Originally Posted by Flieger

The part they rebuild is the motor part.

Where they wear is in the brushes and commutator of the electric motor section.

An '82 does not have MFI. We are talking about the MFI's electric fuel pump.

sounds like the CIS Bosch routine?


and i was on Lindsey Racing site and they have info on installing their pump but i couldn't find out more

http://www.lindseyracing.com/LR/Parts/TECHFPUMP.html

[Flieger]

The CIS pumps do not have enough flow for MFI at high rpm.

That Lindsey Racing one only has one output? MFI has an input, output, and return.