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MG MGB Technical - S.U. Fuel pump trouble

1976 RB MGB. No fuel from fuel feed pipe fuel pump not making sounds, changed and spare pump also not making sounds. Have power at connector and ground (earth) is ok. Any help would be appreciated. Thinking about changing to electric fuel pump.
Orlando

Orlando,

You do have an electric fuel pump!:)

I'd guess your breaker isn't turning over. You can take apart the top of the pump (look at a diagram) and find the problem. Usually, it's pitted points, dirt or something relating to wear. Your spare probably has the same problems from sitting around.

Alternatively, you can buy a replacement set of points. They're very cheap and -I think- quite reliable. If your pump is on the old side, it might be time to replace the diaphragm and filter as well.

All this work is very simple to do and inexpensive. Once you do it properly, the pump should last many years.

On the other hand, if you're a little lazy or feel like expressing your feelings...try smacking the top of the fuel pump with a rubber hammer.
Philip

Orlando - Dheck your e-mail. Dave
David DuBois

My '79 MGB has a similar problem.
Is it necessary to remove the pump? I hope not because I am concerned about gas leaking.
How does one easily access the top of the pump to swing a hammer? I tried accessing it from the battery box with no luck.
My shop manuals are useless in showing how to remove the pump.
Years ago, I had a TF and working on it was a breeze. Oh, for the good old days.
David H

David it's true, removing the pump can be a little messy. But it's not that bad. I just re-placed a Brake master cylinder without removing the pedal box. Talk about jobs that make grown men cry!!

I find the easiest way to 'smack' it, is from underneath. I must confess, I've used numerous items other than a rubber hammer to do this as well. However since overhauling it, it has run just peachy.

To work on it, you need to remove it. It's pretty self-evident (but remember to disconnect the battery!) The hardest part is getting a box wrench around the inlet/outlet bolts and reconnecting the vent hose.

I believe both Haynes and Bentley have good diagrams for the pump. However it's worth plunking down $15 for the Brooklands manual on SU Carburetors -it also covers fuel pumps.
Philip

David - A screwdriver handle please, not a hammer! You are only trying to jar the points loose, not beat the bloody thing into submission. If anybody thinks that I am kidding, I can send you a picture of a pump I received for repair that had been beat to death with a hammer. If a couple of wacks with a screwdriver handle doesn't get the pump going, then it is in need of serious help. You obviously had a 54 TF 1250 and not the later 1500, which has the pump in about the same place as the MGB.

If you have to pull the pump to service it, start by disconnecting the fitting at the top of the gas tank for the line from the tank to the pump. That way when you remove the line at the pump you will only spill the gas that is in the line instead of syphoning the entire tank dry. You will also spill a bit of gas out of the line from the line from the pump to the carbs and from the pump itself. Put a oil pan under the pump when removing it to keep the gas contained. Seriously consider putting a shut off valve in the line from the tank while the pump is out, makes future removals of the pump easier and also serves as a anti-theft device. Also consider permentently installing a back up pump in series with your regular pump in case you ever need it when on the road, you could save yourself a BIG hassle by doing that. If you are interested in these two things or in having someone restore your pump and converting it to solid state, drop me an e-mail and I'll send you information. Good luck - Dave
David DuBois

I would like to thank everyone for their input. As it turned out the new pump was bad and the old pump had cavitated.

I follewed the letter sent by David Dubois and as it turned out no air rushing sound can from the tank cap but some how there was an air leak in the system.

If the pump fails again I will change it from an S.U. to a more modern electric fuel pump by it was kind of fun as well as a learning experiance trouble shooting this problem.

Thanks and Safety Fast
Orlando

Get everything working right then stick to the original SU, aftermarket pumps can also fail and often need added pressure regulators to prevent flooding.

FWIW new pumps usually come with a slip of paper saying to clean the points before returning it as faulty, they can oxydise in storage.
Paul Hunt

Turn to the dark side Orlando, buy a modern Japanese pump.
Peter

This thread was discussed between 08/04/2005 and 11/04/2005

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