RolexNJ

So it sounds it's really the fuel rail itself that is then coming down the fuel lines? As soon as you research more, yet again, let me us know, thanks. Damn, this thing seems like it is never ending?

Duke

A customer of mine installed an extra fuel damper from a 911 turbo (vacuum/pressure regulated) between the supply line and fuel rail and the tapping noise completely dissapeared.

I'm pretty convinced the knocking sound is due to the Marren damper not doing its job (except for the noise transmitted from steel lines rubbing against body).

Tom M'Guinn

I can feel the pulse strongly when touching the damper, although I can't really say if that's where it originates for sure. My car evolves slowly but steadily -- -- so I'll just keep after this knock issue until something works. There must be something that makes it happen, since some big fuel pump cars have it and some don't.

special tool

I have the same pump and lines as you, and it knocks pretty loudly.

RolexNJ

I told you that when we had my old 3.0L too! I hated it.

tconn

I have a stock fuel rail and damper, braided lines. I just have a hum coming from the pump. A little louder now than in the summer but unnoticable
once under way.
I cut the rubber jacket off the old pump and wrapped the 044 pump with it
before installing.

Tom M'Guinn

Just curious, which braided lines are you running (LR, Pauerman, homebrew?) -- and what injectors do you have?

Tom M'Guinn

Thanks. So, did he use two dampers -- one in-line, plus the factory one on the rail?

It looks like the LR fuel rail would allow for a variety of dampers, so I've sent Dave a note asking about that as a possibility.

tconn

Tom ,
I have the Pauerman lines and run 55# siemens injectors.

RolexNJ

That all said above guys, it has to be the LR Fuel Rail, no?

Tom M'Guinn

tconn and I both have stock fuel rails, both have 044 pump, both have pauerman lines, both have seimen's injectors (mine are bigger though) ...

yet mine knocks and his doesn't...

RolexNJ

Ugh!...

tconn

How is the pump mounted? Maybe not enough insulation?

Tom M'Guinn

I wrapped it in rubber sheeting. The pump itself just whirs away -- very smooth sounding and not a problem, even with a mechanics stethescope on it -- no knocking from the pump itself. The knocking sound is coming from the hard lines and/or rail/regulator/injectors it seems.

Duke

I haven't heard any 044 pump that knocks? A sweet whine can be heared though

Yes Tom, the Marren was in its original place and a stock type damper was added on the supply line. That solved the problem.