Fuel Pump Whine?

I fired up my 86 911 this cool morning (about 40 degrees) and there was a high pitch constant whine coming from the engine compartment immediately. The car started and ran great but the noise stayed there all the way to work. When I got to work, I shut the engine off and just turned the key back on and the noise started again even with the engine off. The heater was also off so I know it wasn't the blower motor. Does this sound like a fuel pump going bad? If not, any other ideas? Thanks for your help...

My fuel pump whines like that since I bought the car (1.5 years)never had a problem. Even if I turn the key on with the motor off I can hear the pump whining.
Any other thoughts if this is a problem?

Same with me.
Pump is on before engine cranks.
I have checked the wiring, but not found any "home made" changes.
The pump is whining all through. The old one failed after 1 year of owning the car.
The new one whined until failure only a couple of weeks later.
3rd one is whining since then (~3 years).
Looks like normal.
To check & eventually replace the original rubber surrounding may silence it a bit. Also, a loose connection can introduce more noise into the car.

Jens
'76 CIS with '73 body conversion

Thanks for the replys...it's good to hear I'm not the only one. As of today it is only whining occasionaly, but when it does it is LOUD. I think I'll replace the filter first in case it is so clogged that it is putting extra strain on the pump. Does this make sense? Car runs fine though...certainly no signs of fuel starvation. Oh well, I guess I'll live with it for now.

Mine has always whined, too. Loud, 2 years now. So much so that I am considering a switch to turn it off. So much stuff only works when the key is in the "on" position (windows, lights, etc) that it's annoying to have to listen to that when I'm just testing or working on the car. Plus, if I make it hidden I think it would be a nice added thief-deterrent. Any thoughts why I shouldn't do this?

Just a hint for checking/working w/o getting bored by the fuel pump:
Just pull the Relay!

Jens

Any chance the whine that Paul is hearing "from the engine compartment" is from his ignition unit and not the fuel pump? My fuel pump whines when it runs (only when the engine is turning), but it's up front, not in the back, and is nearly impossible to hear unless I'm standing in front of the car.

The ignition unit also whines (high pitched electrical hum), whenever the ignition is in the ON position.




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Bill Krause
'79 911SC Euro

Good point, Bill.
My fuel pump is in the rear.

Then, question back to Paul:
Did you notice the whine only the first time, or appeared it really the first time?

Reason for asking: I never heard of an ignition which was getting noisier-either it worked or quit...

Jens

Jens, I noticed the whine for the first time the other day and to me it has a definite electric motor hum to it. The pitch is quite high and can easily be heard from any position around the car. Also,if I turn the key to on without starting the engine, the noise will start and then die after about 5 seconds...if I'm not mistaken the electric pump will shut off as a safety feature after a few seconds if the engine is not runnning. Anyone know this for sure?

Mine does not shut off after 5 secs and if I leave the key to the on position to long before cranking the motor floods. Do I have something wrong that my pump doesn´t shut off automaticaly?

Paul,
Like some of the other replies you've had, the fuel pump on my '86 Carrera has whined loudly since purchase, about a year and a half ago. Also, the pump comes on as soon as the key is turned so the electrical power comes on, before the engine starts. One thing I discovered recently is that the pan covering the steering rack and fuel pump was bent upward, probably from being used as a front jack point, and had been brought into contact with the fuel pump. This contact made the pan act as a resonator/amplifier. If this is the case on your car, you can either beat the pan flat (use a 2-by-4 between the hammer and pan), or you can apply a foam weather strip piece to the pump. The foam will dampen the resonant effect of contact with the pan, and quiet things considerably.

Regards. Brian

Just replaced the fuel pump on my '78 911SC. Before, the puymp made a slight noice, just enough to tell it was running. It made the noise when the ignition was turned to the second position, not the accessory position and before cranking the motor. I liked it because I gcould send presurized fuel to the motor withoput having to "wear" the starter motoer. Now, however, there is absoluting no noticable fuel pump noise even wher nthe motor is running. I also lost the ability to run the fuel pump before the motor is cranked. I don't now if the pump was going bad because it was able to pump fuel before the motor ran. Try pulling the fuel pump relay to when the key is turned to accessory position and see if the humming stops. If it does you will now the fuel pump is not the source. Best of luck.

On a 78 911SC with CIS, the fuel pump should only be running when the ignition is in the START position (engine cranking) or when it is in the ON position AND the engine is running. A sensor switch connected to the air flow sensor plate is open when their is enough air flow to lift the plate. When the engine stops, the plate drops and the fuel pump is turned off.

It only takes about a second for fuel pressure to build up to proper levels, so there is little value in having the fuel pump come on any earlier. Also, all of the cold start components (WUR, aux air valve, thermovalve...) are wired in parallel with the fuel pump, so your ability to cold start could also be negatively affected.

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Bill Krause
'79 911SC Euro

It sounds like some of you may be having trouble with your fuel accumulator. When you turn off the car the fuel pressure should remain. If it bleeds down then you will hear the pump run before the car starts.