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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 MGA - Fuel Pump

A few days ago my fuel pump started to click with the engine off once every 4 to 5 seconds. I know from previous comment that this is too fast so I did a fuel delivery test on the front carb fuel line and it gave about 1.3 litres per minute without air bubbles which I think is about right. Frustrated I then took off the pump, split the body and cleaned out the filter etc checked the outlet valve and put the whole thing back - and the ticking got worse. I've left the electrics and points alone on the basis that the fuel delivery rate is OK. Took the pump off again, redid the cleaning but added some gasket seal and put the pump back. This time the clicks went back to once every 3 to 4 seconds. Checked for leaks to pump and pipes and everything is dry. I talked with Burlin and they said there could be grit under the inlet valve. My question for those versed in SU pumps is where is the inlet valve and how do you get at it? The outlet valve is obvious but not so the one way inlet valve. Is there any tech info available for SU pumps?
J H Cole

Dave DuBois in US is an SU fuel pump expert, see his site:

http://homepages.donobi.net/sufuelpumps/sufuelpumparticles.html

Send him a mail if he doesn't respond to this. He is usually active on the MG Experience MGA forum.

Neil
Neil McGurk

Are you sucking air in through a loose fitting between the tank and pump? There should only be two connections 1 at the tank and 2 at the pump. NEVER a fuel filter inbetween those two.
R J Brown

JH - Since you are not seeing any bubbles in the fuel being delivered to the carburetors, there are no leaks in your system, either the pump gaskets or the fuel lines. The fas pumping is most likely due to either worn valve disks or debris in the valves. You don't need to disassemble the pump again, just remove the outlet fitting and take the valve cage out. The valve disk is held in the cage by a spring clip - remove the clip and the disk will just drop out, this is the outlet valve. The inlet valve disk is in the pump body below the outlet valve cage. The disk will drop out by turning the body upside down. Check the disks for wear in the form of groves in the disks. You can lap the disks on some 600 grit sand paper on a hard flat surface (I use the sole plate of a flat iron) until you work the groves out or you gan get new disks from Burlen Fuel Systems http://www.burlen.co.uk/ the P/N for the disks is AUA 839. While the disks are out, check the valve seats for any debris or wear. Usually the seats are ok, but can collect debris that needs to be cleaned out. Cheers - Dave
David DuBois

RJ, no theres not a filter on the delivery side and I don't think I'm sucking in air.
David, I will check the valves as you recommend. By the way when I unscrewed the nut on the delivery side there was a piece of plastic tube about an inch long leading into the body of the pump. Is this normal? I've started fairly low down on the learning curve for these pumps but it seems to me that if both inlet and outlet valves are well seated there should be hardly any clicking of the pump.
John
J H Cole

That short tube on the inlet fitting is normal on the later pumps. I am not sure what the function is as the earlier pumps worked fine without it and it is not there on the later pumps - just something that was used for a short period of time. Cheers - Dave
David DuBois

Could the plastic tube be the filter, or the remains of it?
Malcolm Asquith

I've taken the valves out of the pump, cleaned them and sanded with 1200 wet and dry, reassembled and the clicking is now much improved to about once every 13 seconds which is I suspect is about as good as I'm going to get it. A few observations: it helped a lot to unscrew the outlet pipe union to bleed out air once the pump was turned on and petrol allowed to run through the pump. In the MG Service Parts list, page D1 a coil spring is shown on the inlet valve. I have not seen this spring in other diagrams and assume it has been dispensed with. I've noticed there quite a lot a debris in the pump filter only a short time after the first disassembly. its not obvious rust but looks like small flakes of paint, black one side and reddish colour the other. It must have come from the take but I can't think how it could be produced.
john
J H Cole

I have been reading this thread with interest, so I decided, out of curiosity, to have a look at my pump that has been in the spares box since my rebuild (I fitted a Facet pump).

What I found in the box was not what I expected. Can anyone identify this pump for me? It must have been fitted to my MGA by a previous owner between 1958 and 1974 out in California.

The pump is the correct way up according to the words on the casting.

Steve


Steve Gyles

Malcolm - "Could the plastic tube be the filter, or the remains of it?"

No. I have no idea what it's function (and I suspect that no one other than the person who first stuck it in there knows), but it is not a filter - the filter is installed through the bottom of the pump body as it has been since the L type pump was first introduced somewhere in the dark reaches of antiquity. whatever the purpose was, it has been deemed unnecessary because if only appears for a short period of time and is no longer being used.

Steve - The pump you have pictured is an older AUF 214, and is used mainly on midgets and the original Minis.

John - The spring that you see in the diagram, like the tube on the inlet fitting was used for a short period of time, probably to improve the closing time of the inlet valve. It is no longer used in the AZX 1300 series pumps, probably because whatever improvements were gained by it were not sufficient to justify the cost.

The 13 seconds per tick is about correct for the L type pumps. Cheers - Dave
David DuBois

This thread was discussed between 24/05/2008 and 27/05/2008

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