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MG Midget and Sprite Technical - Fuel Pump

I think I now have a problem with my fuel pump. It is a new 'electronic' SU. It has worked fine for about 500 miles but last week the engine started missing and died. The fuel pump was not ticking. It then started clicking again and the engine started but the pump was clicking like mad. I looked at it tonight after adjusting the back brakes and draining the diff oil and I must have nudged the pump wire as it broke at the connector by the fuel tank. I cleaned up the wires and remade the connection. I then checked the pipes for air leaks and they are all fine. A quick test drive and all seemed ok at first and then it started missing again. The pump is again clicking like mad at idle.
I am tempted to remove the tank and clean it out to make sure there is not a blockage in the tank.
An other suggestions?

Thanks in advance.

D Brown

Thinking about it, when I checked the pipes for air leaks I took both pipes off of the pump and they were both dry.
I don't like the way the pipe from the tank joins the flexi pipe to the pump. It is a little too big for the flexi pipe and I cannot get more than half an inch (if that) into the flexi pipe. To get that much in I removed the pipe and wire from the body and fitted the pipes underneath the fuel tank. Even then I did not get a drop of fuel out of the pipe.
By the way I am sure that I have fuel - the gauge is reading half full and has not been wrong in the past, but now I mention it I think I should just go and check.

D Brown

is your tank clean inside?

From your description is sounded like you've not seen fuel coming out of the tank pipe that leads to the pump. If that is dry your pump will click like mad (and it will quickly burn out).

Norm Kerr

That's what I was thinking.
So an evening removing the tank tonight. It is half full so I have to find something to put 3 gallons of petrol in.
Thanks Norm

D Brown

Pumps click like mad when they are either pumping air, or there is no resistance at the delivery end (carb) So first check that fuel isn't flooding out of the carbs or pipework "downstream" of the pump.

If that is OK then either the fuel level is low in the tank, or the pump is drawing in air through the pipework upstream of he pump. This is fairly common at the union to the tank, but can also be from splits in the rubber pipes. There may not be an obvious leak, as often these won't drip fuel out, but will allow air to be pulled in when the suction of the pump is applied.

If it is a blockage, before you remove the tank try blowing compressed air back up the delivery pipe and into the tank. This often clears an internal tank blockage.

Guy Weller

>>> If it is a blockage, before you remove the tank try blowing compressed air back up the delivery pipe and into the tank. This often clears an internal tank blockage. <<<

Ditto that. I used a can of compressed air that I usually keep at my desk for computer equipment. Just put the little tube in the end of the fuel line, seal it with your thumb, and press the button. If you have an air compressor, that will work too. I had my tank removed when I blew the line out, and fuel squirted at least six feet behind the car. So it's a pretty good method.

You can also check the hose from the tank to the pump to make sure it's not collapsed inside. Compressed air won't fix that...

Cheers, and best of luck,

Gryf Ketcherside

A frequent cause of pump clicking is in the union at the side of the tank

Modern tanks have a slightly different outlet union and the way it seals can allow the pipe to let air in before the pump inlet

It is tight enough not to allow petrol leak out but the olive inside the connection is just puny enough to allow air to seep into the line

I used the often "dreaded" PTFE tape on the threads of my tank connection after yet another case of sucking air, which happenend at a petrol station luckily

When the fuel level was high enough the air leakage didnt happen, so I topped up the tank and drove home untroubled
Bill 1

I have just removed the tank and although it is not in particularly good condition (quite rusty on the outside with a few dents) it does not have much muck inside. I can blow into it from the outlet (I just love the taste of petrol!). There is a plastic pipe from the outlet to the flexi pipe at the fuel pipe and I don't think it has collapsed and I am sure it is not kinked. there is a small worn patch on it where it has rubbed on the handbrake rod (I think) but that is all. I have ordered a new copper pipe as I don't like the joint at the flexi hose end. I suppose I just put it all back together and replace the pipe when I get it.

D Brown

Had another look today and I am getting air and spits of fuel at the carb so it looks like I have an air leak tank side of the pump. A new pipe is on order so I hope to have it fixed in the week.
In the mean time I can get the RC40 and maniflow inlet manifold on.

D Brown

This thread was discussed between 09/09/2010 and 11/09/2010

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