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MG MGB Technical - MAJOR FUEL LEAK

Took the 79 B out for a drive yesterday, finally after the engine rebuild. Pulled out of the driveway and started down the road only to discover the strong smell of fuel and a wet trail behind me and no trail in front of me. Being of reasonably curious nature, I got out and looked under the car. Fuel was pouring from what appeared to be the fuel tank and on top of the differential on to the ground leaving a dual stream of fuel.

My assumption is the fuel lines from the tank have rotted and failed. Have not had the chance to probe as of yet the actual origin of the leak. Are the fuel lines rubber, and how does one approach the removal of the tank to investigate this problem??

Again, thanx in advance

cheers

Gary
gary n. hansen

Gary,

This thread ran a few weeks ago. HTH

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=71&subjectar=71&thread=200407031507137333
Paul Hanley

Gary, Not sure on the later cars but I think the fuel lines are rubber from the tank to fuel pump and from the fuel pump to the main feed line, I think the main feed may be metal. You should not have to remove the tank to inspect or replace the lines. The fuel pump is in the boot so some lines are inside the boot and some are under the car. Someone with a RB car will probably give you a more detailed description of how to change the fuel lines. Good luck, Clifton
Clifton Gordon

Gary, on my 76 the hose from the tank is steel with a rubber hose to the fuel pump and a hose from the fuel pump to the steel main line to the engine compartment. Both hoses are under the car just in front of the gas tank on the right rear side.
Regards,
Dennis
D F Sexton

I was wrong on the location of the fuel lines they are under the car as Dennis said. Clifton
Clifton Gordon

Many thanx Clifton and Dennis. The leak was clearly on the passenger side pouring atop of the differential. I do suspect it is the rubber split. Prior to this the evap canister in the trunk had the hoses disintigrate and I did replace those. So I can imagine the fuel line is gone as well. Not having to pull the fuel tank will be a good thing. I am not fortunate to have a garage and the equipment to do anything much beyond routine maintainance.

I just put about 100 miles on the car since I got it back from the engine rebuild & clutch & brakes, etc. it was too good. I am certain once the details are done the MGB will be a dependable ride. I shall check this out asap

cheers

Gary
gary n. hansen

Gary. The fuel line is steel and runs along the right (passenger) side chassis member. Thus, you would not have the problem you describe unless the steel line had a break in it. Or, unless the steel fuel line had a rubber hose attached to it that was leaking and running down the hard line to that area.

In either case, the solution is to put the car up on jackstands, disconnect and insulate the wire going to the coil, then turn on the ignition switch and see where the fuel is actually leaking from. Les
Les Bengtson

Fuel tanks can rust through as well
S Best

Hmm....
This subject is popping up a lot lately! Dennis and Les have it correct. The problem is that the unreinforced fuel tubing has split or cracked. Replace with 5/16" fuel rated tubing (use new clamps too). You can find them at any auto parts store.

You're lucky you were close to home. The first time this happened to me was in the middle of Ohio on a 95* day, in a construction zone, with traffic backed up for miles due to an accident. There was no shoulder to pull off on. Ended up pushing the car between a couple of construction barricades to get some room to work on it.

Good luck,
Tom
Tom Sotomayor

If your car is original, it may not have rubber lines, but anything is possible afler thirty + years. When I bought mine, it had some rubber lines that cracked, and I found myself sucking air instead of gas (broke between the pump and tank. Not enough gas onboard to set up a siphon effect. If you have any rubber hoses on your car that are over ten years old, they should be replaced as a routine maintenance action. Better safe than sorry.
R. L Carleen

Had the same thing happen to me in my '79, there are two rubber hoses, both the inlet and outlet. Like the previous post, replace with some braided fuel line tubing and you'll be in good shape.
TD

Again, the input from all of you is appreciated. My gut feeling is the hose is more than likely a rubber composition. I just had the all rubber brake lines replaced and the trunk mounted fuel canister lines as well. I would not be surprised if this is one of the details that was overlooked. I do remain optimistic the problem is just rubber hoses and not metal and or the tank is rotted. This w/e is out for probing and perhaps next week as well (rain forcast ALL week long)I will return the post as soon as I address the issue.

Thanx again

Cheers

Gary

PS. I had an unstable braking problem prior to changing out the rubber brake hoses, so again I suspect rubber hose deterioration.
gary n.hansen

From your description of the area where you are noting the fuel, it must be the feed line to the pump. It should be a rubber hose with a barb fitting on one end (gas tank side) and a banjo fitting on the other (pump side). Some pumps had barb fittings so it might be a regular piece of fuel hose.

Let us know what you found, eh?

Mike!
mike!

This thread was discussed between 22/07/2004 and 27/07/2004

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