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MG MGA - Petrol pump

I have never touched my petrol pump and, touch wood, it always works fine.
However, I have a fear that it will let me down one day.
Should I
1) leave it alone,
2) Service it, or
3)replace it with a new 'facet' pump, whatever that is?
Nigel Munford

The old adage of 'if its working leave it alone' is worth considering but if your fretting then take it off and check the filter and points. Pumps very often fail intermittently and can be brought back to life by tapping sufficiently to get you home. Belt and braces would be to carry another pump.
J H Cole

I understand that the pump originally fitted to MGA's was a new type (marked HP) and now give armature trouble which cannot be repaired. I had horrendous problems with mine in the UK some years ago and finished up driving about 200 miles (at night!) with a one-gallon plastic fuel container and plastic hose with ocky straps to hold it close to the windscreen with my long-suffering wife alerting me when we were running low (she could see the level due to oncoming headlights)! Each time, luckily, a service station hove into view! Not surprisingly, I have replaced the pumps on both of my MGA's, one with a new "surplus" MGB SU and the other with an electronic after-market Fuelflo (made in New Zealand, I think) both of which are excellent (although the Fuelflo's tick all of the time, inaudible once the engine starts). Tapping the pump, with the panel removed, works but really only delays the "evil day".
Barry Bahnisch

If you install an aftermarket pump in place of the original one you have to cut ends off the steel lines and connect with hoses. Easy enough if you are prepared for it. Universal electric fuel pumps are available at any auto parts store, lots cheaper then the original type. I happen to like this one:
http://mgaguru.com/mgtech/fuel/fp201.htm
Barney Gaylord

Barney, what is the operating principle of these low pressure pumps? Are they centrifugal?
Art Pearse

The original high pressure HP fitted to the late TFs and early MGAs was what is now called a high pressure, long body pump. While it wasn't the best pump SU ever made, it operated well enough and still does (I have two of them in my basement that I am restoring for a client). the biggest problem with them is that the diaphragm has a long spindle and are substantially more expensive than the later high pressure pumps. If the pump is working with no hiccups, then I would suggest leaving it alone. As long as the car is driven on a regular basis so that any film that develops on the points is burned off, the pump should give you many years o trouble free driving.

JH's suggestion of belt and braces carrying another pump is certainly worth considering. See the article, Backup Fuel Pump in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ for information on a permanently installed backup pump. With this done, if the primary pump fails, one only has to flip a switch in the cockpit to continue on home and a snug garage to change out the offending pump instead of doing it at the side of the road, which is uncomfortable at best and downright dangerous at worst. In my article, I suggest a Facet pump (the noise of those things will be added impetus to get the primary pump working and back in place), but the ones that Barney suggests will work equally as well. Cheers - Dave
David DuBois

Mine recently quit on me. Couldnt get it to go again. So, I picked up a small one at Autozone.

When I went to put the new one in, the SU started working again, (better than before). So I installed the new one in front of the SU (just toward the engine) at the bend in the fuel pipe. Three way toggle, I can switch between pumps or disable the car.
If the SU goes out, flip the switch and I dont even have to pull over. :)
Judd Irland

The little pump that looks like a fuel filter with wires is a continuous running unit. It starts quiet and gets quieter when pressure is up. You cannot hear it when engine is running. In my experience they last at least 10 years or 100,000 miles, and will not crap out from sitting in storage. By 10 years it may go a little rusty, and you need to change the connector hoses anyway, so I wouldn't bother installing two pumps. If you want to carry a spare with a rubber electrical connector installed in advance, it's a 10 minute change over. I dd that once in the past 20 years 200,000+ miles, in the middle of the Alaska trip. I suspect it was actually a clogged inlet filter, but it was easier to swap out the whole unit.
Barney Gaylord

I've decided to get a spare, and carry it with me. What do you recomend that is available in the UK? Moss products never seem popular!
Nigel Munford

Nigel, -- Universal electric fuel pumps are, well, "universal", available anywhere. Maybe try http://eBay.co.uk
Or take a copy of my web page with the picture to your nearest auto parts store and see what they have in stock.

Art, -- The thing is not centrifugal. It is reciprocating with a couple of check valves. Electrically it has an oscillating circuit that simply switches power on and off rapidly, and a solenoid that pulls the core back against a spring. The pumping function is then similar to the SU pumps where the spring provides the output pressure, except that it never stops. When pressure builds and flow slows or stops, the stroke gets shorter, which is why it gets very quiet with pressure up. Moving parts are just the reciprocating plunger and two check valves, one of which may be inside the plunger. I saw a cut-away illustration of the thing once. Nothing could be simpler, which is why it it so reliable.
Barney Gaylord

This thread was discussed between 16/03/2011 and 19/03/2011

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