black944 turbo

My '86 Turbo is making a loud humming noise from the fuel pump after it heats up. This has just recently started and apears to have just gotten louder the last time I drove it. My question is this, is it on its last legs or just simply making more noise?

I just recently did the filter and check valve so I know it is mounted properly and tight in the clamp.

whalebird

I've been discussing this in another thread and have had the same issues. Some say some of these pumps just make noise and that it's normal. It has occured to me that an old filter could be creating resistance, but thats probably not the case for you now that you have a new filter(I've also wondered if the check valve can buzz). However, one often overlooked item is the fuel tank screen. If it is creating resistance(stopped up partially) then there may be a cause there. The bosch pump is pretty hearty unit and will continue to flow enough volume to pass the volume test even with some restrictions in the fuel line (filters), but draw more amperage stressing the pump and DME relay that carries the pumps current. I think a clamp on ammeter at the pumps leads could tell a lot about the integrity of the filters...or maybe these pumps just make noise.
Mine has been doing this for quite some time, even with a new filter and check valve. I will remove my tank screen filter when the current tank is about empty...we'll see.

black944 turbo

Good to know. Mine has been noisy for about 3 1/2 years, however the last two drives where a lot noisier than normal. I am not sure on the sock filter or even how to get at it, as I have not cared to mess with the tank much. Any other thoughts would be great.

mytrplseven

I'm wondering if the rubber boot that is part of the mount has slipped out and it's simply rattling around in the clamp.

gtroth

For me groaning fuel pump was FPR failure.
When it failed, fuel pressure went way high (>100psi of my gauge), and pump did night like working against that I guess. Hot starts also cranked longer than normal, btw.
100% fixed with new FPR for me.
What is your fuel pressure?