steel fuel line buzz Options

[eyesright]

A coupe of years ago I replaced the original fuel lines with steel brake lines. It is a '72 with original FI and fuel pump relocated to the front by PO. I used a right angle fitting at the firewall rather than bend the line. On driving, the fuel lines buzz with a harmonic at all speeds that isn't nearly as prominent when not moving. I have covered the exposed lines with old rubber lines and secured them pretty well but no effect on a still noticeable buzz.

I am replacing the fuel lines now in a '76 and have steel lines long enough to bend.

If the harmonic buzz in the '72 is from cavitation at the right angle joint when there is significant fuel flow, then this should not occur with the '76. (I recognize that there is fuel circulation even at idle, but I don't get near as much harmonic buzz at idle. And it'a a much higher buzz than I would expect from road vibration.)

In the future I'll really tie those suckers down in the engine bay and where ever I can reach in the tunnel in the '72 to see if that helps or replace them with longer ones like the '76 if that is successful.

Has anyone had this problem or any ideas to offer?

[r_towle]

I might suggest that it could be the fuel pump mounting.
If that is done improperly, it turns the car into a speaker for the vibration to amplify.

Did that in the 911, but some rubber wrapped around the pump so the metal clamp did not touch the pump was all it took to stop the noise.

my 914 has the pump mounted up front on rubber isolators for the bracket to body connection, and rubber wrapped on the body of the pump at the pump to bracket connection.

It took all that to make the noise stop in both cars.


Rich