CIS Fuel Distributor Leak?

Jay Laifman · 09-25-2018, 11:43 AM

Sadly I haven't been able to drive my 73.5 911T for about the last 3 months. I backed it out of the garage this last weekend and had it idling for a few minutes while I closed up the garage for my drive. When I went over to the car, I smelled gas and opened the rear deck.

I had gas coming from the area of the fuel distributor. It was not coming out of any of the inlet or outlet lines on top, or the two hoses in the back. It was not spraying out, but a decent flow.

I immediately stopped the engine and cleaned it up. Then I started it, quickly drove it back in the garage and looked to see if I could source the leak. But it wasn't leaking anymore!

The car was idling just fine, the whole time.

Is there anything that could have temporarily leaked because the car was sitting for 3 months, that somehow "cured" itself? I do not believe so. But this is certainly strange.

Any suggestions other than to pull the FD and send it to CIS Flowtech to check it out?

T77911S · 09-26-2018, 02:50 AM

have you ever taken the FD apart?
if not I would be hard pressed to think fuel was leaking from the 2 halves of the FD. the FD has a metal gasket or shim between the 2 halves and its just not prone to leaking.

you can run the fuel pump and check for leaks again. if no leak then start it up and check again.
try tightening the fuel lines to see if any are lose.

RarlyL8 · RarlyL8's Garage

I just fixed a similar problem on a 73.5 CIS 911T and have seen it a few other times. The cause was not the same in all cases. If there is a leak above the upper half of the FD the fuel can migrate down to the split and follow that split around the circumference of the FD so it looks like that is where the leak originates. For the FD we just repaired the split was actually leaking. On others one had a pressed on fuel line that would weep intermittently and another had a banjo fitting with the same issue. What I did was clean everything off thoroughly with alcohol, let it dry over night, then observer with a dental mirror while someone else starts and runs the engine.