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MG MGB Technical - fuel pumps

The electric fuel pump on my 72 B has become unreliable?? There is a blanking plate on the side of my engine where presumably a mechanical pump could be fitted.Also I seam to recall when I rebuilt the engine(some time ago) that there was a cam on the cam shaft for driving a mech.fuel pump. Question can I use a mech fuel pump and which one ?
regards Brian
B R pasmore

The cam was for a mechanical tacho drive, not a fuel pump. There are lots of options on aftermarket pumps and some good reasons for sticking with the SU; I'd suggest a browse through the archives to get opinions from all sides.
Steve Postins

I've never hear of a mgb with a mechanical pump.
If you are fed up with using an SU and want to get going ASAP then try a Japanese pump.
Before I installed the EFI V8 I was using a second hand electric pump from a 1982 Subaru wagon that I just happened to have when I finally gave up on my SU fuel pump. The damn thing would not work on the Westgate bridge here in Melbourne. A huge ten lane, upper stratosphere, "stop and you'll be killed", 80KM/Hr bridge on the way to where I worked. It worked everywhere else, just not on the main span of that bridge. A Honda one works as well as the subaru one I'm told.
A very quick install, I just jammed it (out of sight) in that small space/corner at the back/side of the engine compartment with a bit of rubber mat around it. Location and hoses kept it firmly in place. The most time consuming part was bypassing the SU with a bit of fuel line.
It stayed there for 6 months working perfectly until the V8 went in. If you get one from a breaker/wrecker then they can be found at the top back of the engine compartment and are easy to extract.
To be fair your SU is probably very old (40 yrs?), and over due for replacement. If you do persist with the SU pump, I would advise against trying to rebuild it yourself. Get a fully rebuilt guaranteed one. I gave this (point replacing) a pretty good shot, bought some expensive points and adjusted them endlessly while enjoying the dizzying petrol fumes . I suspect the actual solenoid/main windings were damaged/worn and you need a large press to get those out. It is useful to know that you can sometimes get the pump to kick over by giving it hefty thump with a hammer (which has a certain 'feelgood, take that, you #@$%!' factor about it). However I very quickly got tired of lying under the car bashing at the fuel pump while trucks roared past inches from my vital organs.
Peter Sherman

Brian - Yes, a mechanical pump can be installed (remember folks, the B series engine were used in a multitude of different vehicles, some of which used mechanical pumps). the problem would be in finding which pump fits (an e-mail query to Burlen Fuel Systems at: http://www.burlen.co.uk/) might get you an answer as they also make mechanical pumps (I wonder it they also make the tick, tick, tick sound). That said, it is not a real great idea to put a fuel pump on the side of an engine where it is pulling fuel under vacuum into a hot engine compartment - a recipet for vapor lock. Either get a new SU fuel pump (go with the all electronic pump), an aftermarket pump or send the errant pump to one of the people who can overhaul them. A list of people wh repair the pumps can be found at the end of my article of fuel delivery trouble shooting at: http://www.mgexperience.net/article/fuel-tsg.html
Regardles of which way you go, you might want to consider a permanently installed back up pump as described in my article on the same at: http://www.mgexperience.net/article/backup-fuel-pump.html Cheers - Dave
David DuBois

I'm not sure if there is room to install a mechanical fuel pump on an MGB engine. I have looked at several MGB cams and all I have seen had a fuel pump lobe between valves 2 & 3. The blanking plate should be on all 18V blocks. Look at the cam photos in the Peter Burgess site. They have fuel pump lobes between valves 2 & 3
http://www.peter-burgess.com/cams.html
The MGA/MGB cam in this Crane site also have the lobe.
http://www.importperformanceparts.net/imports/cranecams-mg.html

Clifton
Clifton Gordon

How old is your SU pump? And how many years and tens of thousands of miles of good service has it given? My roadster pump eventually gave up the ghost so I replaced it with the same type. The V8 had an electronic equivalent of the SU ('pointless' being a very apt description), and that started playing up, and unlike the points-type SU you can't tap it with a screwdrive or tickle up the points to get it going. I refaced and reset the points in the original roadster pump, fitted that to the V8, and both roadster and V8 have been fine ever since. The 'pointless' pump sits in my garage as a reminder that more modern isn't always better.
Paul Hunt 2

I have just fitted a new electronic SU pump. Previously the car was suffering fuel starvation at high revs and on steep hills, the new one fixed all the problems.
At roughly the same time I fitted electronic ignition, Nepean Classic cars in Sydney had a special offer (About $200) service exchange complete new / recon distributer, just bolt in, what a difference this made to the car, like having a new engine fitted.
Mark
Mark

Amazing what replacing faulty components will do, regardless of whether they are replaced by OE or 'upgrades' ...
Paul Hunt 2

Folks,

I've just read David DuBois' post above and this own website entry regarding a back up fuel pump. I completely agree with what he said but what about this for another option. It came to me while considering a 1500cc MG midget with a mechanical fuel pump and a small fuel tank but may have other uses.

Due to the small tank I wanted a reserve capability so that I didn't run out of fuel if I trusted the fuel gauge too much but I didn't want to take up part of the mall boot (trunk) with a can of spare fuel. I considered fitting an electric pump in parallel with the mechanical pump. Each pump would have its own pick-up tube from the fuel tank and then feed into a common supply to the carburettors. By fitting a slightly shorter pick-up tube and using that for the mechanical pump, the car runs out of fuel normally but switching on the electric pump gives a 'limp to the filling station' capability. The electric pump also gives a 'get home' capability.

As a potential side benefit, one could use the electric pump to 'prime' the carbs before turning the engine over and using the mechanical pump normally. Careful use of relays could allow this to be done automatically before being switched off when the engine starts.

Unfortunately, I never got round to fitting the extra pump before my Midget was destroyed by fire - in a garage overnight not caused by a fuel leakage!

FWIW

Peter
Peter Hills

The arrangement you describe, with the different height pickup tube was a common arrangement in prewar cars. They didn't use separate fuel pumps, but a two way valve. The only problem with this arrangement is remembering that you have turned the valve to reserve and getting stranded when the reserve fuel is used up. Cheers - Dave
David DuBois

Those of you in the MGCC can take a look at the SW Centre Notes in this month's Safety Fast where you will see an MGB fitted with two pumps and a changeover switch...

N
Neil22

The two different pickup system was used all the way up to 1961 in the VWs. Prior to 1961 they didn't have a fuel gauge (if I remember correctly) and after 1961 they didn't have the lever up under the dash that you could "flip over" with your foot when you startee to run out of gas.

FWIW

Larry
61 Karman Ghia (a long long time ago)
Larry Hallanger

The two level pick up system with a mechanical valve has been used on motorcycles forever. I had a Chevy truck with dual tanks that used a solenoid valve for switching tanks, Ford used a mechanical valve for the same purpose. Either could be used in place of two fuel pumps but the two pump system would be the most redundant. Of course you could still be out of luck if the pump for the deeper pickup quit.
John H

This thread was discussed between 22/11/2007 and 26/11/2007

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