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MG MGB Technical - SU Electronic Fuel Pump O Ring

Hello Everyone,
I finally decided to replace the original
SU pump on my '73 MGB after 36 years and 152,000 miles with not one hiccup! I figured its time had to be running out, so rather than get stuck on a country road at night I decided to replace it and have it bronzed.
My question is: on the new electronic SU pump there are O ring in the tops of the ports where the banjo fittings go. Do I still need a fiber washer between the banjo and the pump with this in place?


The answer is covered in this excellant site
DK McNeill

Why do they have to mess? What was so bad with having identical fibre washers either side of the banjo fitting?

As far as the old points pump goes, I'd just check and possibly replace and reset the points, and use it for another 36 years and 150k! I'd had a new SU pump for a while when the points on the old one in the roadster packed up so I swapped them but refurbed the points. The V8 came with an electronic pump (Moprod, not SU) which was fine for a number of years but then started intermittently short-stroking causing fuel starvation. Once that happens you are stuffed, until it decides to start working again. Usually when you get problems with the points they can be resolved with a sharp thump, for a short time anyway. Even though on one occasion it was doing it at home, and as it was a rubber bumber with the electrics end in the boot I could open it up to see what was happening, I still couldn't find out what was wrong. After the third bout I junked it and fitted my refurbed points type, and it has been fine ever since.
Paul Hunt

Ralph - No fiber washer between the banjo fitting and the inlet/outlet ports, just the 'O' ring. To insure that the 'O' ring seats into the recess in the ports properly, press it into the recess with your finger such that it stays in place, then offer up the banjo fitting with banjo bolt in place and tighten the whole thing up. See the article, New SU fuel pumps With 'O' Ring Seals in the SU Fuel Pump Articles section of my web site at:

Paul - I'm with you regarding the 'O' rings, I couldn't see any reason to make the change, but they did and now we have to live with it (or stick with old pumps). As for sticking with the old points style pumps, that is fine for the person like you and the others of us who drive their cars regularly, but for the average owner (at least on this side of the pond), their cars are only driven a short time during the summer months and put into hibernation during the winter months. the result is that the pumps don't get run enough to bun off the accumulated film that develops on the contacts and since the lower contacts in the points set are difficult to access, they never get cleaned properly and the owner has continual problems with the pump. You would be amazed at the number of MG owners over here that proclaim that the SU fuel pump is a worthless piece of crap that should never have been set loose on the unsuspecting public (there is one contributor on this site who is particularly vitriolic on this subject). The all electronic pumps now supplied by Burlen Fuel Systems appear to work quite well over a long period of time, with the only downfall that I have seen is that they are rather fragile to sustained periods of constant current if the pump stalls in a current on condition, such as occurs when the fuel tank vent is clogged. Also judging from the absolute lack of returns of the pumps that I have converted to an optical trigger, I have to assume that they too, are working properly over the long term and both pumps have eliminated the problem of long periods of inactivity. Cheers - Dave
David DuBois

Thanks, guys.

I have installed the pump as suggested and everything seems fine. I have also just installed a new fuel tank, so the gasoline should be clean. The old tank had to be dropping many particles of iron oxide!


David - I never think of myself as doing much mileage, only about 3k per year in each of the three. Even when I can't use the two MGBs over winter like for the last two or three years (this Feb I filled the tank for the first time since August) I still run the engines about once a month.
Paul Hunt

Paul - I think that compared to the majority of of MG owners, your 3K per year would be considered high mileage. When we got our first MG back in 74 (a 53 TD which we still have), everyone drove their cars a lot and MGB were considered everyday transportation mules. Now days, TDs a rarely driven (even ours is only taken out on an average of once a week) and MGB are not driven much more than that, although the MGB is still our primary transportation vehicle. Even so, being retired, we probably don't put many more miles on it than you do (no more commuting - probably the best part of being retired). Cheers - Dave
David DuBois

This thread was discussed between 28/03/2009 and 30/03/2009

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