78 SC Fuel Pump Noise - problem solved

[stormcrow]

Since the rebuild on my 78 911 SC Targa I have driven over 80,000 miles. During that time I removed the gas tank, cleaned and coated it and re-installed it.

Well for the last few weeks I have been noticing the fuel pump has become more noticeable noise wise when the car is at idle. Today I decided to find out what the problem was.

I installed a hose clamp pliers on the hose to the inlet side of the fuel pump and remove the rubber tubing off the fuel pump. I was going to completely remove the fuel pump but I noticed a screen on the inlet side of the pump.

With a small pointed tool I removed it and to my surprise it was half full of particulate matter. I removed all the particulate matter which appeared to be a brown substance - not sure what it was. Flushed the screen from the outside to thoroughly clean it and re-installed it.

Reconnected the rubber hose to the inlet of the fuel pump, tightened the clamp, removed the hose clamp pliers and fired up the beast.

Well apparently the blockage was causing the problem. The noisy fuel pump is no more and it appears the P-car runs a bit better.

So for those of you who own older P-cars I would definitely recommend checking out your fuel pump inlet to see if in fact there is a filter inserted inside the inlet pipe.

It will save you from buying a new one at best.

[matt930s]

Thanks Steve. I also have a 78 and my fuel system seems to "sing" from the CIS and I notice a definite fuel pump noise. How would you characterize the sound you were hearing before removing the obstruction? Is the pump now silent completely or is there still a mechanical sound?

Thanks
MattR

[john walker's workshop]

never seen one. weird.

[stormcrow]

Matt,

The noise from the fuel pump could be heard while being in front of the vehicle while it was running. In the past I never noticed it being that loud or for that matter ever noticed it running at all.

Once I cleaned the blocked screen and re-connected the fuel line, started the engine the noise went away.

Apparently with the filter being half full from the end of the fuel pump tubing it was restricting gas flow causing the noise.

It isn't a whining sound but it was noticeable enough to let you know the fuel pump was there. .

[stormcrow]

Johnny

One thing that I didn't mention is that this is an aftermarket fuel pump with the aluminum body - sort of looks like a inline fuel filter but bigger.

The original fuel pumps didn't have a screen filter in them.