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MG MGA - no fuel

My car runs fine for about ten miles and then it runs out of fuel. I can take the hose off that goes to the carbs and the fuel barley comes out. The fuel pump clicks about every 15 seconds and a small blurp of fuel comes out. I have had three different fuel pumps on the car and the last effort I put an extra fuel pump in line to give it more pressure. The only thing I can think of is that something is blocking the fuel pick up line in the fuel tank. Other than that I am lost. Any suggestions?
GK George

Disconnect the fuel input at the pump connect a flexible hose and place in a container of fuel. If it comes out of your carb. hose freely (with your pump on) then you've elimnated the tank and it's output line. If it doesn't then undo the pump outlet and connect another flexible tube. If no fuel it's your pump otherwise it's your pump outlet line partially blocked. If it were me I think I'd use paraffin in your container for these tests for safety reasons..........................Mike
m.j. moore

Have you got a fuel filter in the line?
Chris at Octarine Services

Well if you have replaced the pump recently, it's unlikely to be that.

There is a strainer in the bottom of the pump, but you would need some serious rubbish in the tank to block that in 10 minutes (though not impossible)

What sort of filler cap do you have?
Is it a (non-original) screw cap with a perfect airtight seal?

The only vent in the original car's tank is via the hinged filler cap - no vent means that as fuel is used, a partial vacuum builds in the tank and the pump can no longer suck hard enough.

David
D Brown

GK you probably have a fuel filter in line somewhere that is partially blocked. I had similar intermitent symptoms to yours which took me months to sort out.

I found an aftermarket filter down near the fuel tank that you couldnt really see until you took the rear wheel off. It was a glass one and it looked perfectly clear until I took it apart and found some clear silicone sealant floating about which moved over the outlet hole after a few miles and cut off the fuel.

If there is no filter you may still have something floating about in the fuel line that is causing the problem. You could try disconnecting the fuel pipe at each end and blowing through it with an air line from the cars end to see if you can clear it out. Put a cloth or something over the end to catch anything that blows out and

When the pump is working correctly should be able to deliver at least one pint of fuel per minute to the carbs.

I once fitted an SU fuel pump that was meant for a Morris 1000 and the car ran short of fuel at higher speeds but ran ok at lower throttle openings. So check to see if your pump is the HP version of the SU pump or at least its equivalent.

But I think you are right to suspect your fuel line first.

Colyn
Colyn Firth

GK - First thing to do when the car appears to run out of fuel is to release the filler cap for your tank. While the design of the filler cap is such that the vent is difficult to clog, stranger things have happened and if it is clogged, the tank will draw a vacuum as fuel is used and will eventually form a strong enough vacuum for the pump to overcome. For more troubleshooting tips, see the article, Fuel Delivery Troubleshooting Guide in the SU Fuel Pump Articles section of my Homepage at: http://homepages.donobi.net/sufuelpumps/

A clogged filter can also cause the problem as others have suggested. Further on the filter (for others also), if you have a SU fuel pump and the filter is located between the tank and the pump, it should be moved to the output side of the pump to avoid damage to the pump - see the article SU Fuel Pumps, Facts and Myths in the same section of my Homepage, linked above. Cheers - Dave
David DuBois

I once had an ongoing problem with fuel blockages which I believe was caused by 'instant gasket' that I had used to fit the fuel gauge sender. It then disolved in the petrol but then coming out of the petrol and blocking pipes so this may be need checking.

Paul
Paul Dean

I think the above covers all obvvious points. Just one random question - is it possible that the pump is the wrong way round?
g Victors

Well mike I tried your suggestion. Took the line off at the carbs and turned on the key and it pumped very little. Hooked up a rubber hose to the inlet of the pump and put the other end in a can of fuel. The pump started to pump like it was supposed to. Then I put on another fuel tank and drove it for about 5 miles. I will try a longer trip today in the day time. Thanks for the suggestions.
GK George

Drove it 30 miles yesterday and had no problem. I had the fuel tank coated with something after cleaning and that must be the problem. We will see what that guy has to say.
GK George

Had a friend with an MGB who had this problem. Fuel tank coatings do not like the ethanol we have in fuel these days. Better not to coat the inside of new or old tanks, in my opinion.
Peter.
P. Tilbury

This thread was discussed between 23/09/2013 and 29/09/2013

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