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MG Midget and Sprite Technical - Electric fuel pump on a 1500

While i am in tinkering mode, i am considering the possiblities of fitting an electric fuel pump onto my 75 1500 midget.
I know anything is possible, but does a 1500 work well with one, and if so what sort is best. Facet do a variety of pumps as do otrher companies. I did read that SU's dont like too much fuel feed pressure. What sort of pressure is too much.
The reason you ask for thinking about this mod. Well the Midget suffers with poor starting from cold and i thought it may be a pump issue. I did buy a new mechanical pump but it simply didnt fit. It was a good make but a poor copy.
Thanks.
S Langston

Hi,
I had a time recently where the mechanical did not work well, I had a spare but couldn't get the pressure correct and was flooding, starving, all sorts of things. I changed to an SU pump and it works really well. Most SUs are mounted underneath the car which makes it difficult to work on so my SU is mounted in the engine bay on top of the pedal cover just below the clutch and brake reservoir. The good thing about the SU is that if the car has not been started for a week or 2 one does not have to crank the engine as in the case of the mechanical pump. With the SU just switch on hear the pump working until the sound stops and then fire up the engine. Hey Presto.
Mark Wilson

Mark

I'm not sure if this is fact or fable but apparently there are 2 different types (excluding different pressures) of SU pumps. One type is the version fitted to Midgets and Bs and is designed to fit close to the tank, the other type was fitted to the likes of Morris Minors and is fitted in the engine bay. The difference, apparently, is that the Midget type being fitted close to the tank needs minimal suck but more force (pressure?) because of the long feed whereas the Minor type is the opposite, needing greater suck and less force. If this isn't true someone will be along soon to dispel this myth.

Bob
R.A Davis

Link to the Burlen website including installation details:

http://www.sucarb.co.uk/TechnicalDetail.aspx?id=53

My SU catalogue also states that the pump should be kept well away from exhaust heat.

HTH
Doug Plumb

There were two types of mechanical pumps fitted during the 1500's production run, and you may have gotten the wrong one. Later 1500's had a thermal spacer that fit between the engine and the pump; this necessitated longer mounting studs and a different actuator arm on the pump itself. This spacer was much like the one fitted between the inlet manifold and the carb(s).

That said, the factory-spec pump was calibrated to the optimum pressure for the carburetors. The pumping is actually accomplished by a spring under the diaphragm, and the rate of that spring is what moves the fuel along and holds pressure when the float chamber fills and the float valve closes. The movement of the actuator arm merely pulls the diaphragm down and primes the pump so the spring can push another dose along to the carb.

I had a mechanical pump fail once, but this was due to a defect in that particular pump, and not to the basic concept. I replaced that one years ago, and haven't had a single pump-related problem since.

As for the electric pump providing instant starting, I think I'd rather use those initial engine cranks to pump oil around the engine before it fires! :-)

Cheers,

-:G:-
Gryf Ketcherside

As Gryf has already said, there are 2 different types of pump fitted to the 1500, the early one which your old pump will be and the later one, that you obtained, all you need to fit the later pump is 2 longer studs and the insulating block, this arrangement is an attempt to keep the pump a little cooler. I did this on my car, but i am not sure it has improved things at all.

This should give you a better idea:
http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=1421

and if you are tempted to go electric, this would be a good place to see what is available and then hunt down a cheaper source.

http://www.moss-europe.co.uk/Browse/PlateMenuProducts.aspx?WebCatalogID=39&PlateTypeID=1&SubcomponentID=508

I did go as far as buying a facet solid state cube type pump, which is rated at about 4 PSI, which i am told is ok for SUs, but i have not fitted it so i can't say if this is correct or not.

Alan
A Pritchett

This thread was discussed on 27/10/2011

MG Midget and Sprite Technical index

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