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MG MGB Technical - Fuel Tank

Is there a screen at the end of fuel feed pipe inside the fuel tank?
Could it be getting clogged occasionally?
My fuel pump, a low pressure electronic purolator type, will operate fine for a while then start rapping loudly, like it's starving for gas. Shortly thereafter, the accelerator pedal becomes unresponsive, the engine sputters and stammers and eventually cuts out.

I have a inline filter installed between the tank and the pump. It collects some fine flakey debris but it is not clogged.

It should be noted that this tank was just recently re-installed and is the original tank(68B-GT). I thought I cleaned it out pretty well, about a year ago, using a degreaser and a etching liquid. I did not use a tank sealer.

I'm planning on draining and removing tank today and recleaning. Would it be advisable to run a wire down thru pipe and poke a hole thru screen, if there is one, and let filter catch debris from now on?

thanx for any input
DS
Dennis Silance

My MGA's tank standpipe was completely clogged when I bought it. In order to run a wire down it (I used an old speedo cable in an electric drill) I had to drill a #1 hole in the 90 degree fitting and later fill it with an allen type 1/4" setscrew. Another problem you could be experiencing could be a cracked hose between your tank, filter or pump. Had that happen on my B--I use the same setup you do btw. Pump gets loud 'cause it's sucking air. Crack opened and closed based on different factors. Eventually it failed completely. Never saw fuel leaking from it.
R. L Carleen

Have you fitted a non vented cap - if the tank it not vented the pump will draw till the suction in the tank overcomes the flow.
Chris at Octarine Services

chris- I thought about the cap, also. still does it when loose.

R.L.- All hoses,pipes are new from tank to carbs. I did check for leaks but not air leaks. It funny you mention that though. I emptied tank by disconnecting pipe at carb junction and pumping it into cans. Fuel pump made same infrequent rapping sound and air could be seen going thru line at that time.
Dennis Silance

The '68 tank (OEM) on my B had a small red plastic filter attached to the bottom end of the pick-up tube. The only way to get to it was to cut a hole in the tank and pull the filter off. Then I tacked the tube to the interior bracket, with the end about 1/4" from the tank floor and welded the patch back on the top of the tank. Not a bad job really.

Tom
tom

If you're pumping air, you could have a hole rusted through your standpipe.
R. L Carleen

Dennis - can you see the pickup pipe through the guage sender unit ? If not - try blowing back into the tank to see if that might indicate either a blockage or an air leak. I suspect the latter - on the inside of the flange where it attaches to the tank shell. Alternatively, the pickup may have been badly installed above the tank bottom or the new rubber feeder pipe may be too flexible and is collapsing under suction.

For the record I have once picked some debris which wrecked the pump - I seem to recall that it had some synthetic fibre in it which allowed it to work badly - we fitted a filter before the pump.

FWIW

Roger
RMW

There is no filter in my replacement stainless tank, the pick up is attached to a small bracket welded inside the tank . It's an early car and just has a vented filler cap . Never a problem .
S Best

You don't say how long 'a while' is, but if more than a few seconds then I'd say the pump was giving up, possibly one of the non-return valves. If a variable length of time then possibly there is some debris like cloth or plastic swilling about in the tank which is eventually getting sucked up and blocking the strainer, which is what I though was inside the tank. A peforated pickup pipe would give the effect of running out of fuel always at the same fuel level, irrespective of how long it had been running. If 'a while' is very short it could simply be fuel starvation to a constant blockage or a weak pump, running on what is in the float chamber until then. But if the pump starts hammering loudly and rapidly shortly before the running problems start then it is either the pump itself or a blockage, or possibly an air leak, back towards the tank. Remove a pipe from a carb and direct it into a container. It should consistently deliver at least 1pt per minute.
Paul Hunt

This thread was discussed between 10/11/2004 and 12/11/2004

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