What is that "whine?" Is my fuel tank contaminated?

[toddetch]

Hi, everyone, when I first took possession of my '80 SC in June pretty much the first thing I noticed was what I can only describe as a "whine" that seemed to come from the front. Upon opening the trunk and taking out the carpet, the whine was louder and it seemed to me that there was a cavitation in the fuel tank. Along with a number of other things that needed to be repaired, the fuel pump, check gasket, and fuel filter were replaced. The mechanic said the fuel pump was noisy and when I picked it up they said the filter was very dirty and the pump had a bunch of gunk in it.

Now, according to the records I have the fuel pump was replaced about four years ago and supposedly the car hasn't been driven that many miles since then. Also, I believe the car sat for about 12 years before that and I didn't notice anything in the documentation about cleaning the tank or installing a new one. When I got the car back everything seemed much better. However, I started noticing a similar whine again this weekend - not near as loud but definitely there.

This afternoon I removed the fuel level sender and peered inside. I didn't see stuff floating around or anything. I did get two videos: the first is what I could see inside, the second is just to try to capture the whine sound. Notice that in that second one as I bend over towards the fuel tank it is more noticeable.

So, those of you with more experience than me, do you think this is a fuel tank problem or is it something else? Thanks!

View inside the tank: https://youtu.be/AjRhYRTIz1w
With the car running: https://youtu.be/6tANhzFnc9o

[75 911s]

Stick your phone right under the front suspension if you can. The fuel pump is located under and behind the tank under a plate. Can't tell if the whine is coming from the fuel pump or if your fresh air blower is making that racket. Turn off all your air controls in the cab, shut the doors etc.

If its coming from the pump, it's probably bad or will be soon.

[toddetch]

Originally Posted by 75 911s

Stick your phone right under the front suspension if you can. The fuel pump is located under and behind the tank under a plate. Can't tell if the whine is coming from the fuel pump or if your fresh air blower is making that racket. Turn off all your air controls in the cab, shut the doors etc.

If its coming from the pump, it's probably bad or will be soon.

Thanks, Duane. The plate you mention is missing (noted by the mechanic). I started it and tried laying the phone done as close as possible. Hopefully this is helpful: https://youtu.be/LBAFqRBZnQM

[75 911s]

I would definitely source a used plate from one of the usual suspects. You need that to protect the new pump you will be buying. :-) I can't tell, because I'm not there, but if it's coming from the pump, then in my opinion it could fail soon. Plus that whine is annoying and will probably get louder.

For the plate:
Partsheaven
20th Street auto
Ebay
Pelican WTB classified

The pump you can buy here on pelican. There's an aftermarket version and the Porsche version. The Porsche one will be roughly 18 million dollars. Good time to inspect the fuel lines. If your mechanic said the fuel filter was dirty you might as well replace that too.

4 years is enough time for fuel to go bad and get gunky. Clean fuel helps cool and lube the pump. I think some guys install inline filters before the pump. The inside of your tank looked normal to me. It's hard to see into the swirl pot, but if you are worried, you can empty the tank and have it cleaned.

Good luck!

[Guardsred911]

you can also just flush your fuel pump out... that might help. use Diesel (NOT GAS!!!) and reverse the polarity on the battery. Do it outside and ideally have your car outside to limit fume build up.... look up instructions on the forum.... might just be crud in the thing... .

[jferrante]

I literally just posted a WTB for that cover as well since mine is missing..hopefully we get a bunch of hits.

[DRACO A5OG]

+1, Fuel Pump ready to go.

Warning Porsche is not much better. I replaced my old one due to age, nothing wrong with it but when I swapped to OEM Porsche 2.25 years later it started to whine, of course after the warranty. I just put my old one back and annoying wine be gone.

[toddetch]

So I wonder if it is really the fuel pump if the gas tank is fine. It is new - only a month old and around 300 miles on it. Could there be junk in the lines?

[SCadaddle]

The fuel pump in my 82SC sounds like a door open warning buzzer from inside the cabin when I get off the highway and come to a stop. It is LOUD. Yours per the video is very quiet compared to mine. Hasn't failed on me yet only because I've got a new spare pump on the shelf.

You won't see any trash inside the tank and inside the swirl pot because it has a lid on it. And like all the others around here will tell you, the fuel pump is actually cooled by the fuel, so best practice is don't get too low on fuel. If the fuel light on the dash comes on, then you are already too low.

[pmax]

Originally Posted by toddetch

View inside the tank: https://youtu.be/AjRhYRTIz1w
With the car running: https://youtu.be/6tANhzFnc9o

That's a pretty clear video of inside the fuel tank.

Fuel pump whine sounds "normal" to me but hard to tell really based on a video.

[T77911S]

check to see how much current the pump is pulling. should be around 7-8 amps.
make sure the pump puts out what it should

I don't think that is all that bad
my pump made a lot of noise for 10yrs....

['78 SC]

and fuel filter were replaced

Did this include cleaning or replacing the screen that screws into the bottom of the fuel tank?

Mine was making a terrible racket (cavitation, I suspect) until I cleaned the tank and screen. That was more than 25 years ago and the pump is still fine.

[toddetch]

By the way thanks everyone for you responses. To answer @'78 SC it did not include replacing the screen in the tank.

I'm also beginning to think it may be the fresh air blower as well. I'm keeping an eye (and ear) on it.

[T77911S]

i did not see the year of the car.
if it has autoheat controls the footwell blowers may be running,.
mine did that even in the off position. if I turned it to hi then back off again it stopped,
I eventually fixed the autoheat controls