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MG MGB Technical - Another SU Pump Issue

Well, this one is probably for David, but I’ll take info from anyone that has it.

My SU pump is clicking away when I kick the key on. It is not leaking, and the car runs fine, so I assume the check valve between the pump and tank is not doing its job.

Is it likely that I can correct the problem by taking out the check valve and cleaning it up?

If this is just run-of-the-mill wrench stuff, I can probably figure it out. But, if there are any gotcha issues that I need to consider before crawling under the car, it would be nice to know ahead of time.

Thanks to David’s instructions, when the car quit in California, I already have a second pump plumbed into the fuel line. So, I’m not worried about getting stranded, I just don’t want to take a gas bath, nor do I want to screw up the SU pump.

By the way, I think the problem I had in CA with the fuel pump was all due to a loose license plate bracket. I suspect that the fuel pump grounds there. However, though I did tighten the bracket, I have not removed the jumper wire that I ran from the battery when it quit again in Oklahoma. Sometime I will get the time and courage to disconnect it and see if the car still runs.

Charley
C R Huff

This is the same problem I'm having. From what I gather, it means the pump is drawing in air somewhere, or as you say the non return valve isnt working. Burlen fuel systems do rebuild kits for these pumps so if your going to be taking the pump out to try and fix it, I'd get this kit. Replacing the gaskets and seals as well as the valves would be a prudent move in my opinion. It also comes with new points and a new diaphragm. That should eliminate the problems I reckon. I'll be doing my pump in a couple of weeks so I can give you my advice and pitfalls from a novices perspective doing the job for the first time and how I overcame them.
Ross Kelly

One of the Reed Valves (In, Out) is probably
leaking.

They're made of a thin plastic and they develope
a hairline crack before they totally go kaput.

They're easy to change, once the pump is out
of the car.

-----

Less likely (but not out of the realm) is that the
diaphragm might have developed a crack and
is leaking.

The Bentley Manual gives detailed instructions
on how to replace and adjust the diaphragm.

-----

In both cases, no special tools are required.
Daniel Wong

Thanks Guys,

I probably won't do a full rebuild because I already have another new pump plumbed into the car, and it would start doing the job anytime I swap the wires over to it.

I don't have the Bentley, but now that I know what I'm looking for I suspect that I can find it. Do most of the MG parts supplies have the valve available?

Hmm, come to think of it, I might have a Bentley for my Spridget.

Charley
C R Huff

An air leak on the inlet side of the pump or a bad check valve (or some debris trapped in it) will cause the problem you are experiencing. It could be a torn or cracked diaphragm, but those are very rare and if it is the diaphragm, you would see fuel leaking out from th event tube or the edge of the diaphragm. Cheers - Dave
David DuBois

Thanks David,

I'll have my self a look-see.

Charley
C R Huff

This thread was discussed between 17/06/2008 and 18/06/2008

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.