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MG Midget and Sprite Technical - Mechanical fuel pump

Hi all,

I have an oil leak from behind the mechanical fuel pump. Just wondering if there is anything worthwhile doing while it's off? Obviously I will replace the flexible hoses and clamps. Or is it best to go for a better electric one and delete the mechanical?

Ta!
Karl Bielby

Nothing wrong with the mechanical ones. Except there is one practical flaw. If your carbs have drained down for any reason (e.g. car left with the choke pulled out, or left standing for more than a few days and fuel has evaporated), then to refill the carbs you have to rotate the whole lump of the engine, with the consequential drain on the battery, just to operate that little fuel pump!

If in this situation it helps to allow the engine to turn on the starter through maybe 3 or 4 revolutions, then pause for the count of 10, before then pulling out the choke and attempting a start. The reason is that the mechanical pump builds up some pressure by doing this, and the 10 second pause allows this pressurised fuel to feed through and fill the carbs.
GuyW

Early mechanical AC-Y types have a primer for refilling the carbs but it is left off modern replacements.
Reconditioning kits are available from tractor dealers as the pump was used on tractors both petrol and diesel.
Alan
Alan Anstead

Karl
Have a look at your oil leak before diving in---
If the leak is from the gasket itself, ok replace the gasket---all good
But check to make sure the oil isn't coming out the little breather hole in the pump and running down the pump onto the bottom of the pump/gasket---If it is, the seal on the pump lever is leaking and the pump will need a reco.
willy
William Revit

I replaced my mechanical pump a couple or three years ago. Supplier just had a problem identifying the pump arm. All OK and working fine since (15000 miles). As Guy says after a lay up it needs a crank to prime. Otherwise it does what it says on the tin just fine.
Dave Squire

After a small Google session, it seems the mechanical pump isn't up to much after a few mods. Mine has air filter, exhaust, cam and smaller carb needles so it may be a little stretched..

Also forgot to mention it's a 1500.. not that it matters a great deal.

You might be right though William as I did notice that the body was also wet.. will have to look again.
Karl Bielby

I have a mechanical pump on the V8. It's OK but has 2 major issues on that engine - 1) it can't keep up if applying heavy right foot for more than 35 seconds (HOW MUCH FUEL!?!?) and it suffers terribly from fuel vaporisation as it can't suck air. It still has it but is assisted by an electric pump in the back.
Rob Armstrong

Hmmm, best to change do you think? Or is it overkill? It's not a cheap job if you get a pressure regulator as well...
Karl Bielby

This thread was discussed between 01/11/2016 and 05/11/2016

MG Midget and Sprite Technical index

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