Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Fuel system not pressurising

My early Mk3 midget has been off the road for some time, and I'm trying to get it back running.

It turns over fine, and there is fuel in the tank, but it won't pressurise.

By that I mean what used to happen when I'd get in was the fuel pump would make that clicky whirr noise for a few seconds until pressure built up, but now it just does that endlessly.

Has anyone had that problem, or have any suggestions for what to try to troubleshoot it?


N K Baker

Hi Nigel,

First thing is pull off the fuel hose to rear float chamer and see if fuel flows out.

If not, detach the outlet pipe from the pump and see if it pumps fuel.

If not, take the union off the tank and see if petrol comes out.

I guess there is fuel in it of course?
SR Smith 1


Check the state of the pipe between the tank and fuel pump and the tightness of the tank union, it sounds like the pump is pulling air not fuel. Also dip the tank to get an idea of the fuel level as if the internal pick-up pipe has rusted it can pick-up air when the fuel level drops below the union or rust perforation, that'll be covered if you top the tank up to above the union if it isn't already.
David Billington

More simply, smack the pump with a hammer, the diaphragm is probably just stuck.
J White

If the pump is clicking, it is unlikely to be the diaphragm stuck.

As David said, it could be sucking in air between tank and pump.

I had a similar problem on my B and found a tiny pinhole in the pipe from the tank, right at the highest point of its arc over the axle.
Dave O'Neill 2

fuel filter gummed up ?
Andy Phillips (frankenfrog)

Most of the time its a diaphram if you hear a clicking noise and there is no hole in the fuel lines

but if there is no clicking noise and its in the pump ..its ither a bad ground needing cleaned up or its the points inside the pump that need cleaning and reset... common if the car sits along time non started as the points contacts like to corroud over time like the points inside the dissy


Have you tried pressurising the tank just enough to push the fuel through to the pump to prime it?

On several occasions I have had an air lock in my facet pump due to fuel surging in a 1/4 full tank and drawing in air and not being able to purge itself. Even with the tank filled, it was unable to clear the air lock until I put a bit of air pressure behind it to push the fuel over the top of the axle and into the pump.

Colin Mee

Thanks all. As the car wouldn't start, it was going to be difficult for me to get it onto ramps to check under the car, so I went for the easiest option, more fuel.

After adding another 5 litres (a total of 10), it did pressurise, and after some cranking, started on <4. After a couple of minutes, all 4 kicked in and it was running fine.

A final note, remember to move any car parked immediately behind your spridget get before you start it up, especially if it is white.

Thanks again,

N K Baker

Nice... your not the 1st to try killing the enviro with a midget...haha

This thread was discussed between 14/05/2016 and 16/05/2016

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.