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MG TD TF 1500 - SU Fuel Pump AUA25

So I have been trouble shooting an issue with my car for awhile now and finally I think I have it narrowed down to the fuel pump. I purchased my pump new in 2006 and is a SU AUA25. I disconnected the line going to the carbs and pumped gas for about 30 seconds before the pump quit. Turned the key off and back on and it pumped for about 5 seconds. After that I rapped on the side of the fuel pump and it would pump, then not pump. I did this several times with the same result. I have not taken the cap off yet, but my understanding is that this unit has points? Anybody have experience with this unit and this issue? How hard is it to replace the points? Or maybe I should just replace the unit? Any thoughts would be great appreciated.

Thanks,
Rich
Rich King TD 8732

Sounds to me like you might have a blockage in the fuel line between the tank and the pump. I would check that first.
R E J Stewart

I have two Morris Minors and a TD with the AUA25 pumps. I find that cleaning the points every few years keeps them working well. I usually remove the screwed on blade and clean it, and its mating point, very lightly with an abrasive disk on my Dremmel tool.
John Quilter (TD8986)

It does sound like a points issue. Try to burnish them with some 600-grit sandpaper, just a couple of wipes should clean of any gunk.
Rod.


Rod Jones

Rich,

As mentioned by Stewart, it could be the feed pipe being blocked. Do you have a fuel filter in this line? If so you should remove it, if not then check the state of the tank filter and the pump filter.

John

J Scragg

the suction stroke is powered and pressure stroke is by spring. Any restriction on the suction will stall the pump and overheat the coil
Ray TF 2884
Ray Lee

Check the internal filter as well as the inlet port for debris
Steve Simmons

If all the above don't fix the issue, Take the screws off from the diaphragm and twist the diaphragm to the left one hole. Hook the power wire and ground back on and see if it continues to click.

If not, back it off another hole.

It could be that you are just a little to tight on the diaphragm.
Bruce Cunha

Hey all, thanks for the advice. So far I have cleaned the points and it seems to have fixed the problem. I still need to take it out for a drive (other then around the block) and see if that problem is truly fixed. I will keep you all posted.

Rich
Rich King TD 8732

Agreed. The points have a tendency to glaze over if not run in a while, including when new. Cleaning points is part of the suggested annual maintenance.
Lew Palmer

Been fighting this for some time. I finally replaced the points today. The old points after further inspection were just toast. Replacing the old with the new was a bit of a battle. Things did not line up correctly. Bad parts? Who knows but there was some work to make everything line up right. All is good now........but...We ran the car for awhile without the cap on the front of the fuel point. It was sparking a bit. Is that normal?
Rich King TD 8732

Early pumps had a diode fitted across the coil, later replaced by a capacitor across the points, before finally using a Varister. either may be missing or faulty. These were for spark suppression and make points last longer.


B W Wood

This thread was discussed between 14/04/2024 and 27/05/2024

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.