Mystery fuel leak

Need some help with a technical problem - ask away and let's see if we can all help.

Moderators: hot66, impmad2000, Nige

Post Reply
fcd911
DDK slapper chatter
Posts: 326
Joined: Wed Dec 17, 2008 9:33 pm
Location: Shropshire

Mystery fuel leak

Post by fcd911 »

Last Friday I started my Targa for the first time since last September :oops: . I disconnected the coil, let the pump fill up the fuel lines with Shells finest. (lots of gurgling noises), turned the engine over on the starter for about 20 seconds then reconnected the coil, it fired absolutely instantly. Amazing. I left it on a fast tick over and had a look underneath, to my dismay there was fuel dripping from the vicinity of the fuel pump (out of sight, back left just by the Torsion Tube on a 2.4S). Switched off and searched DDK for fuel line recommendations, then rang 911Hillclimber to discuss. Did some research and identified a couple of ethanol resistant options.

This morning I got underneath to weigh up what I needed. However all the pipes looked to be in excellent condition, I had changed all the fuel lines about 10 years ago after a previous post winter fuel leak. There was no deterioration of the pipes (marked up as SAE30 J6), they were bone dry and there were no leaks, not even when bending / flexing the pipes with the pump running . Went on a 5 mile drive without issue. My only thought is that something like a gasket on the fuel pump had dried out and having got “wet” has resealed itself. I am feeling a bit uneasy, I do not want to be driving around dripping fuel so will need to keep a very close eye on things.

I think I may need to replace the fuel lines anyway for peace of mind and may be rebuild the Fuel Pump, assuming this is possible.

Has anyone had a similar experience or have any thoughts as to a likely explanation?

Thank

John
John

DDK Member: 0471
1973 911S 2.4 Targa RHD (35 years ownership)
Peter
I luv DDK!
Posts: 816
Joined: Thu Nov 13, 2003 5:55 pm
Location: Kingston upon Thames

Re: Mystery fuel leak

Post by Peter »

My fuel line had a split last year and had similar intermittent symptoms, I thought I was going mad! Having looked under the car after a strong smell of fuel and seen fuel seeping out, when I got it out another time to do a proper check, there was nothing. Put the car away again and thought I was going mad, until another day, determined to get to the bottom of it, got the car out again and instantly fuel seeping out again...strangely, felt relieved!
Peter
'72 911T
'52 80” Series 1
User avatar
inaglasshouse
DDK 1st, 2nd and 3rd for me!
Posts: 2450
Joined: Fri Mar 28, 2014 9:35 pm
Location: Surrey, UK

Re: Mystery fuel leak

Post by inaglasshouse »

Original style fuel pump for MFI? Sooner or later they all leak!
Yes, the design does mean that a dried-out O-ring could plausibly cause a leak. Or it could just be on its way out.
Phill

Re: Mystery fuel leak

Post by Phill »

I don't wish to state the obvious but did you check to ensure it was fuel dripping and not something else?
fcd911
DDK slapper chatter
Posts: 326
Joined: Wed Dec 17, 2008 9:33 pm
Location: Shropshire

Re: Mystery fuel leak

Post by fcd911 »

Yes original style MFI Fuel Pump.

It was definitely fuel and it was not just seeping out it was dripping out. Have been on a 50 mile run today and everything was perfect (I kept stopping to check). Probably will be perfect until a period of inactivity.

Are you able to overhaul these Pumps, does anyone know if there is a kit available? I have just looked on the 911 Design website and a new pump is silly money. The Pump on my Rally car is quite noisy so that is in need of some TLC as well.

John
John

DDK Member: 0471
1973 911S 2.4 Targa RHD (35 years ownership)
Post Reply