gf261

I have a high pitched buzzing coming from the right rear and/or center rear of my 89 auto. Fuel pump maybe? Does this mean that it is about to give up the ghost? Planning a 200 mile trip for next date and just curious. Rather stay home than pay the towing bill. Thanks!

Scott M.

gf;

Some 89's have two fuel pumps, one internally, one externally. You have to pull the fuel pump cover off the tell whether you have 1 or 2. (the cover, at the bottom rear of the tank, is held on by 2 nuts at the upper edge, a 10 mm wrench will do the job). If you have two wires going 'into' the bottom of the tank, you have 2...
The external pump is easy to diagnose, bend down behind the car and listen for the loud buzz.
Then again, a loud external pump may indicate that the internal one is toast. Some have found that the rubber hose that attaches to the internal pump has swollen and allowed fuel pressure to bleed back into the tank.
I did a dual pump-ectomy this summer for a friend, took me all of 30 minutes from start to beer.

Scott

gf261

Thanks Scott. I do sincerely appreciate the help. The noise is loud enough that I am sure that it is the outer pump if there are 2 of them on my model. Might as well do them both though I suppose. Thanks again.

DMG

gf, Save you old pump. ecspecially the external one, I threw mine away after hearing the same noise, then I later relaized it would have be

DMG

what i meant was: Keep the old one in case the one you replace it with fails, it's good to have as an emergency replacement

Scott M.

Forget about saving the old one, there is like a $100 core charge on those puppies.

SharkSkin

What are you comparing it to? Did it suddenly get noisy, or are you just getting around to noticing the noise? Can you listen to somebody else's and compare?

chaadster

gf261,

yup, sounds like the fuel pump. failure, however, is not necessarily imminent. i had a buzzing pump that i rolled on for four months without issue. a change of filter solved the problem, which was apparently a fuel starvation issue. I don't have the in-tank pump, either. in reading threads in the archives here while diagnosing my problem, it didn't seem that fuel pump failure was sudden and catastrophic, either. so i'd recommend you start there, with a filter replacement, unless you know that it was changed recently. who knows, you may get lucky and save a couple hundred bucks!

gf261

Dave, I just began hearing it today. I was running down an electrical problem and noticed it. (An electrical problem that thankfully with help from several Rennlisters was finally solved.) It isn't awful just yet, but I want it to be right, not just passable. I will try the fuel filter first as mentioned above, since it is about due anyway. Thanks again everybody above!

SharkSkin

Garrett, just thought I'd ask. Seems like you never hear the pumps on these cars from inside, but then step outside by the rear bumper and they seem loud.

DMG

I think I would rather eat the core charge, and have the ability to get home

jetrainor

This has me curious now about my fuel pump....from day one I've been able to hear it humming...just turn the ignition on without cranking it over and it hums. It never struck me as a problem because i have heard other fuel pumps make noise, although not in a 928. I'm thinking my 87 S4 Euro has only the one external pump and that the round unit at the top of the tank which you see from the rear storage area is the sending unit.
jet