MFI Fuel Pump Leak Help

[73S]

Hello all, I have a 1973 911S. I was taking the car out the other day and noticed a relatively large gas leak by the rear driver's side tire. It looks to me like the leak is coming out of both the send and return fuel line ports (bottom of pump and back side respectively). The pump was rebuilt only a few thousand miles ago (although around 10 years ago). Is this likely to be just an o-ring? I'm trying to avoid having the car towed for obvious reasons and there is a lack of good Porsche mechanics in my area. Thanks for any help!

[50/50]

Turn your key only to energize the pump (not the starter) when cold, let it build pressure and check the lines to and from the fuel console. you may have to take the top of the air box of and have a flash light to see the return line and the MFI pump. Good chance the ethanol has degraded the lines. Lucky that you caught before flaming it.

[Flieger]

My car has run 10% ethanol gasoline for the last 9 years at least. Had a rebuilt pump put in about 3 or 4 ago. Car sits for weeks without driving. No problems with fuel leaks. Still could be just age or a hose clamp that has cut the line or a loose clamp or something.

[edmayo]

Why not jack up the car (put stands under it) wipe the fuel pump dry of fuel, then have some one turn the ignition on while you watch the dry pump. You'll see right away where the leak is actually originating. I doubt it is the fuel lines, from the sound of your usage level I'd say more likely the square section o'ring between the outlet housing and the pump body. Sometimes just continual cycling of the pump will get gas in there which will swell up the o'ring again and may actually stop leaking on its own. I've done that several times.

[73S]

Thanks for the replies guys. I was incorrect in my original post--its the fuel filter housing that is leaking. I can't really see where it is coming from. Basically both the send and return hoses are wet where they connect with the housing, and the gas just runs down the outside of the lines. I guess I'll just start with replacing the filter and the hoses and see if that works. Those hoses are probably 15 years old anyway.

[mobius911]

I've found that the fuel filter cannister can be hard to seal. cleaning out the grooves for the o-ring, using a new o-ring (comes with new filter), and elbow grease is what fixed it.

Changing hoses is a good idea. I found a fuel leak that was running down the lines and accumulating under the fuel pump. Turned out the return line was leaking. It may have been in the rubber itself or at a crimp. Hard to tell with the braided covering. FYI, the new supply and return lines look different. Not braided, and IIRC on the supply line the hard metal length that comes into the engine bay has a drab green military look to it. It's not a gold cad anymore. Lines were purchased from Porsche.

[simonadot]

hello , i have a 73 911 that leaks fuel next to the left rear tire on cold start , then stops after warm. have you heard about this issue with mfi, and is that normal. doesnt seem safe.
thank you in advance.

[TurkisTii]

hello , i have a 73 911 that leaks fuel next to the left rear tire on cold start , then stops after warm. have you heard about this issue with mfi, and is that normal. doesnt seem safe.
thank you in advance.

I'd start by looking at the fuel hose/clamp from the cold start valve. It's the green hose in the photo below.

[RSTarga]

I know those braided lines are the original "look" but if you have a fire you will regret not changing over to newer ethanol resistant lines. The foam engine mat is highly flammable also. I speak from experience.
Also everyone should have an ELEMENT fire extinguisher and know how to use it, or at the very least a Halotron.
Even a small flare up can cause quite a bit of damage.