968 GUY

So, riding into work one morning, i hear a noise like a two stroker going through the gears. Turns out to be the fuel pump. Not only that, the dampener hose burst as I pulled into work. Had just been talking to someone about building one.
I bypassed the dampener til the brand new dampener hose came in and took a chance on the pump by riding short distances in case it quit, besides, had a full tank of gas and wanted to use all I could before changing the pump.
Ordered a new pump but it took a while til I could change it. In the meantime, I switched off between the 968 and the 951. Fuel pump was quiet at times and howling at others.
Completed the swap today, started, ran, no leaks, but the same noise! Car was still on jackstands and I could hear and feel the noise was from that area. Fuel filter is fairly new, a new check valve came with the pump.
I tested the old fuel pump and it was quiet!
So, any ideas folks?

fortysixandtwo

Get a fuel pressure gauge on there. I can see having too much pressure being a potential root cause for both the loud pump and the burst fuel line.

Check the hard and flex lines for any dents, corrosion, kinks, etc... that may cause restricted flow.

968 GUY

Thanks, I have the stuff to install a fuel rail pressure gauge, just another thing I haven't gotten around to.
I have been looking into changing the other flex fuel lines. Hard lines all look good, and will definitely change the fuel filter.
Hate spending money to change something that seemed to be a sure bet, then have to throw more money at it.
What is the proper way to remove the sound insulator sleeve from the fuel pump? I ended up cutting through the top part to slide the pump out.

968 GUY

Made the fuel pressure gauge adapter for the fuel rail, as I could not find a kit at the parts store that would

work on my car. Had my Dad watch for leaks and pressure. He said the pressure sat at 30 for a few

seconds, then jumped to 100! Tried it a couple more times and there is a noticeable grunt when the

pressure spikes. New FPR on order. I now know the system is tight!! I still want to replace and do the

rerouting/wrap on the supply and return line in the engine compartment, since the dampener line is shiny and new.

refresh951

Check the tank screen. I got some bad fuel with dirt in it and it clogged the screen and then the pump gets very loud. Screen is easy to pull and check but you will need to drain the tank. I jumper the dme relay and use a hose off the FPR to drain the tank.

968 GUY

Thanks Refresh. I know I replaced the screen on one of the cars, can't remember if it was the 951 or one of the 968's.
Hopefully the new FPR will cure this.

968 GUY

Replaced the FPR. pressure holds at 40 at idle, rises when I add some R's, pump is quiet.

Now I have a new fuel pump, a good spare pump, and a new filter. Time to change those old hoses.