How loud is my fuel pump (with vid)

[ncoder]

https://www.youtube.com/shorts/Yh3md6YVwzA

I'm worried about the sound my fuel pump is making. It's been rather loud as long as I remember, but now the wine 'beats' in and out from the front pump. (you can hear in the beginning of the video)

Is it near death?

Reading the forums, I still need to try:
1) Test current draw (what's the target amperage?)
2) Test fuel pressure (2 bar when both running, 4 bar when just the front one is running, if i remember correctly)
3) Check for debris in the tank screen. (anyone have good links on how to do this?)
4) Replace fuel filter? (what's the test for this?)

I'm worried about the pump that is in the front.

Anecdotally, I've had hesitation after long 0-60mph+ pull. Hints to me at fuel starvation, but not sure.

If that noise is normal, do any of you run an aftermarket pump that is less loud?


I have a 1986 930, but i assume it's the same stuff on most CIS 911s.

[avenbugt]

What I think: the fuel pump is only supposed to run in the start position and, of course, when the engine is running.

[boyt911sc]

Originally Posted by avenbugt

What I think: the fuel pump is only supposed to run in the start position and, of course, when the engine is running.

Your understanding of the FP operation is WRONG!

Tony

[Chsnsurf]

Did you have two little wires connected on the fuse panel? From what number to what number and why?

[ncoder]

Oh, yes. I intentionally bridged the relays so that I could hear them by themselves, confirming that the noise I didn't like was indeed the fuel pump. (and which one).

[avenbugt]

Originally Posted by boyt911sc

Your understanding of the FP operation is WRONG!

Tony

Tell me more about it.

[boyt911sc]

Originally Posted by avenbugt

Tell me more about it.

There is a long thread by DKLEVER48 about fuel pump relay and the five (5) terminals namely 87A, 87, 86, 85, and 30. Take your time to read them and when you are ready, we will have a good and thorough discussion.

Tony

[avenbugt]

Originally Posted by boyt911sc

There is a long thread by DKLEVER48 about fuel pump relay and the five (5) terminals namely 87A, 87, 86, 85, and 30. Take your time to read them and when you are ready, we will have a good and thorough discussion.

Tony

What I know is what I said before; my fuel pump is only running in the start position and when the engine is running. And this has been so for the last 18 years (with the same pump)

[wazzz]

Originally Posted by boyt911sc

There is a long thread by DKLEVER48 about fuel pump relay and the five (5) terminals namely 87A, 87, 86, 85, and 30. Take your time to read them and when you are ready, we will have a good and thorough discussion.

Tony

Tony, I think there is a misunderstanding between you two.
What avenbut said is the FP runs only when cranking and once the engine has started. And this is correct. It has always been so since 1976, when this safety feature was introduced on CIS cars. Goal is to cut power to the FP in case the engine stalls, like in an accident, for instance.

There's a good illustrated and animated diagram here from AndrewCologne's own web site.

[avenbugt]

Originally Posted by wazzz

Tony, I think there is a misunderstanding between you two.
What avenbut said is the FP runs only when cranking and once the engine has started. And this is correct. It has always been so since 1976...

There's a good illustrated and animated diagram here from AndrewCologne's own web site.

That is exactly what I mean

[ncoder]

This is great guys.

Anyone want to tell me about the pump noise? Does yours sound like this? Or is it quiet?

[pmax]

Try https://forums.pelicanparts.com/911-930-turbo-super-charging-forum/

Not familiar with the 930's fuel pump setup, I won't be surprised if it differs.

In general, it's hard to tell what's normal volume, exacerbated by the fact that the vid's taken in an enclosed room.

[avenbugt]

Originally Posted by ncoder

This is great guys.

Anyone want to tell me about the pump noise? Does yours sound like this? Or is it quiet?

I’ve noticed that when you’re in the car with the doors closed, the noise is practically negligible. And when your engine is running, you probably don’t hear anything at all (inside the car).

[Jaymanbikes13]

Originally Posted by ncoder

This is great guys.

Anyone want to tell me about the pump noise? Does yours sound like this? Or is it quiet?

I have owned a 79 911SC for about 8 months and my fuel pump is very loud, sometimes I can hear it over my radio. I purchased a replacement thinking it is on its last leg. The car runs great so I am a bit apprehensive about swapping it out.

[ncoder]

Originally Posted by avenbugt

I’ve noticed that when you’re in the car with the doors closed, the noise is practically negligible. And when your engine is running, you probably don’t hear anything at all (inside the car).

I hear every mechanical part like an instrument in an orchestra. The fuel pump sounds out of tune with the band.

Informally, it sounds like some of us have louder pumps than others...

930 or 911, yeah. It's a different part number, but the fuel system has the same architecture. It's probably just a difference of max flowrate and/or pressure. But what do i know.

[Chsnsurf]

My fuel pump only sounded that loud before it died. Replaced it two years ago and haven’t heard a sound since (other than when it first primes as I turn the key). I seem to be having an issue with mine even turning on at the moment though, so what do I know. For sure yours is loud. Might be the vibration of it working is resonating against some metal. Might just need a shift in its position. Might need a new fuel pump. Hard to tell. Try repositioning first and if still making the noise, swap it.

[EC900]

Mine screamed like a banshee all of a sudden. Cause: Ran out of gas, low fuel level. Obviously struggled to suck up any fuel, when it did the screech went away until I came to a stop.
Found my fuel gauge/sender was defective, inaccurate and registered under 1/4 full. Replaced and no further noise, still won’t trust the gauge.

[ncoder]

Originally Posted by Chsnsurf

My fuel pump only sounded that loud before it died. Replaced it two years ago and haven’t heard a sound since (other than when it first primes as I turn the key). I seem to be having an issue with mine even turning on at the moment though, so what do I know. For sure yours is loud. Might be the vibration of it working is resonating against some metal. Might just need a shift in its position. Might need a new fuel pump. Hard to tell. Try repositioning first and if still making the noise, swap it.

Good point about moving it around. I'll add that to my checklist.

[ncoder]

Originally Posted by EC900

Mine screamed like a banshee all of a sudden. Cause: Ran out of gas, low fuel level. Obviously struggled to suck up any fuel, when it did the screech went away until I came to a stop.
Found my fuel gauge/sender was defective, inaccurate and registered under 1/4 full. Replaced and no further noise, still won’t trust the gauge.

My gauge is also inaccurate. This gives me one more reason to drain the fuel and take a good look inside.

[ncoder]

Amperage test or front pump comes out to 6.6 amps. Normal?

Also, here's another longer video of my pump's sound.

https://www.youtube.com/shorts/gz5xq0uKslg

It used to run an more 'even' hum. Now you hear it 'gyrate', for lack of a better word.