RoyaleWithCheese

I have an '83 944 that is making a wicked high pitched whining noise from the rear.

It's not a mechanical whine but sounds more electrical. I thought it was the speaker amp that came with the car but I recently gutted it to start turning it into a race car and removed the amp.

Also to note is that it doesn't happen every time I drive it but when it does happen, it's consistent regardless of speed which is what makes me think it's electrical.

Is there a "hatch ajar" alarm? Noisy fuel pump? Should I unhook the electric hatch unlock?

Usually car noises don't bother me but this is driving me nuts!

John_AZ

The high pitch whine may be coming from the rear hatch passenger side "well"---actually the fuel pump.

I replaced both of my fuel pumps -'87 & '88 924S. After a long drive in 100*F + temps, the fuel pump sounded line it was burning out--loud whurrrrrrrr.

I initially changed the tank fuel strainer, short hose to pump and fuel filter.

The new OEM pumps have been quiet for the last few years.

GL
J_AZ

Justin S2

I changed my fuel pump, check valve, fuel filter and lines about two years ago. I still get the whine and I think it may be fairly normal.

RoyaleWithCheese

Ah I see.

Funny how you mention the 100+ degrees because yesterday it was HOT and the whine was much louder than usual.

I'm setting up a light weight 2 speaker stereo in it so hopefully that will be enough to drown it out on hot days. At least until I have time to replace it.

CyCloNe!

Irish car bomb

Doug's 83

My 83 just started doing the same thing. Fuel pump and filter were replaced, but there is likely a lot of crop from the tank being cycled through through system. Should I proactively change the filter again? I've only gone through about half a tank since I got it started after sitting for 17 years. Who knows what evil lurks in that tank!

931guru

Can't hurt, might help.

924RACR

Replacing the filter can't hurt, agreed - but realize that your fuel pump is not protected by that!

Consider flushing the fuel tank as well... pull the outlet hose and see what the fuel looks like as it comes out, let it run until it's clean. Otherwise you're using a very expensive pump as a garbage disposal on the tank...

As for the fuel coming out... lawnmower, maybe?

Doug's 83

Great advice. Thanks! Any thoughts on why sometimes it starts right up and other time it's a no start? I had the timing and reference sensors replaced, could it be the "washer" gapping? Also, if I put it on the trickle charger for a while it will turn with no problem. The battery was new last summer, but it did sit a whole year without a charger. Thanks, as always!

walfreyydo

Check your fuel pressure (kits are $40 on amazon and youll need a M12x1.5 adapter to screw into the fuel rail, I believe). If its low, you have an obstruction (filter clog, check valve issue, fuel tank screen clog) causing the pump to work overtime and "whine" - a whining pump is not a happy pump

Doug's 83

Thanks. I'll look into that!

Breakaway944

You need to get a little more specific about this.Is it hot or cold? Does it crank or not (you mentioned trickle charger)? Is there tach bounce? Any information provided will help
I have had two "crank no start" scenarios. One hot, one cold. Cold one was caused by wiring under boot, for the DME temp sensor, was frayed and sometimes shorting out. Hot caused by bad solder joint on DME for coil driver.

Doug's 83

Generally only on cold. If I out it on the trickle charger when I leave for work, it will crank when I get home. Very, very slight tach bounce, that's why I'm wondering if it could be the new speed and reference sensors not being "gapped" correctly?

Doug's 83

What is the collective opinion of the group about installing an inline fuel filter before the fuel pump?

walfreyydo

Porsche didnt have one from the factory, no need to add as long as the other parts of the system are working correctly.

The tank screen should be checked and replaced and that acts as your inline filter. When you replace the screen you can also flush the tank at that time as well to get out as much residue/sediment as possible, if present.