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MG MGB Technical - Replacment Fuel Pump

Hi,

I am considering replacing the Original fuel pump on my MGBGT, does anyone have any views the best location to fix an aftermarket pump?
Also if you have replaced your pump have you used a fuel flow regulator?

Cheers

Mike
Mike Heath

Fit the new pump preferably in the original position. I know that behind the OS rear wheel is a bit of a pain but if you are only replacing the original now it can't have been too bad. Don't fit under the bonnet as its a bit warm in there. Fit either an original or pointless SU as that way you are sure that the pressure won't be too much for the SU carb needle valves. It also obviates the need for an unnecessary regulator which I assume you mean pressure and not flow regulator as the flow is controlled by the floats and needle valves.
Iain MacKintosh

Why an aftermarket pump? Many *do* need a regulator as they output excessive pressure which can otherwise overwhelm the float valves. Some are also much noisier than the SUs, you are also likely to have to jury-rig mounting and inlet/outlet. I can never see why anyone would bother. The original SU is an extremely reliable pump, as long as you clean the points once every 25 years "whether they need it or not". There are electronic versions of the SU, but having had problems with those that left me stranded that an original points type would not I've gone back to the points type.
Paul Hunt 2

After a spectacular bad time wrt the horrid SU fuel pump, one day, as a temporary measure, I very quickly plumbed a subaru pump up in the engine comparment.Wrapped a bit of foam rubber a round it and jammed it into that out of the way corner at the back of th engine compartment. Took about 15 minutes all up. And there it stayed, working better and more reliably than the SU for a couple of years, until I put in a fuel injected V8 which needed a different pump. I left the evil SU in situe and simply bypassed it.
The pump was out of an '82 model. I'm told this is the same as the Honda civic.
I put a filter before the pump to protect it. The pump sounds the same as the SU (ka-puck ka-puck etc )but can easily pull up through the filter to the engine compartment. How did I know this would work? Because the suparu pump can be found up in the back LHS of '80's Subaru engine compartments. Go and get a couple from a wrecker and carry a spare, for peace of mind. If the subaru pump fails (unlikly) you can replace it in about 10 minutes with just the aide of a screwdriver, because it is so easy to get at. There is no (and I can't emphasize this enough), no, lying around in the mud, under the car.
You can always spend huge amounts of time and money rebuilding the SU later on, if you want to go all concourse.
Peter

FWIW a PO saw fit to put an SU (off a Jag?) at the back of the engine compartment of my Roadster, near the carbs. I've only had to hit it with an Abingdon spanner once, and I can confirm it was easier to swing at.
Steve Postins

Mike

Check the archives for much more information on this. You have to be a member to access them but it is free and only takes a minute or two. You will find that many people will plumb in an aftermarket pump in series with the SU with a selector switch. This way if the SU fails you can switch to the backup and continue on your way. And there are inexpensive aftermarket pumps that have the correct pressure output. It is all there in the archives.

HTH

Larry
Larry Hallanger

1985 Honda Accord pump. Fits in stock location, sounds just like an SU and is dirt cheap brand new at any auto parts store.
David

I have just fitted a new electronic pump from Quinton Hazell it replaces the cheap plastic ones that Moss sell (that have plastic threads that break open).

The one I have fitted was £40 and is a proper metal bodied pump and very well made, looks the same as the original SU but maybe a little more reliable.

Got it from www.elitemg.co.uk
whiskeyfrank

Thanks for the advice
Mike Heath

To answer the original post.
#1 In general an electric fuel pump is placed in the rear and at the same level as the tank because pumps are more efficient pushing fuel than pulling it. To mount a pump on the heater shelf introduces 2 problems that can cause vapor lock. #1 the heat in that area is greater and #2 the pump works harder to pull fuel than to push it. For operational reasons rear mount is "better". A front mounted pump would be easier to change.
When Subaru mounted the pump up front they used 2 fuel filters one in rear by the tank and a fuel separator/filter next to the pump. The front mounted filter has 3 lines one from tank, one to the carb and one to the fuel return line to the tank. To leave off the return line as I expect Peter did appears to work fine but increases the chance of vapor lock. I just checked fuel pressure on a Subaru at the inlet of the front fuel filter the pressure was 3 psi at the outlet the pressure was 2 1/2 psi. The return line bled off 1/2 psi of fuel pressure. Fuel is returned to keep it cooler to avoid vapor lock.
Question #2 The answer is it depends. If you chose a pump that puts out over 2 psi a regulator would be a good idea.
R J Brown

Mike, if you are replacing the original pump then who knows it could be 30+ years old. How can you possibly improve on that record of reliability besides you have all the brackets and fittings and the delivery pressure will be correct. It's a lot less hassle and keeps originality.
Iain MacKintosh

This thread was discussed between 06/10/2005 and 11/10/2005

MG MGB Technical index

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