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MG Car Repair/Fuel Pump????


QUESTION: Hi Barrie,  I have the pump off and purchased the dual points you suggested.  You mentioned you had detailed instructions on how to put the points on.  Would you please send it? The wire on the old points was only held on by a couple of strands so I thought I should get new ones.  Thanks, Sandy

ANSWER: Hi Sandy.

Here is an extract from my book (Barrie's Notes):

New points can only be installed correctly by adjusting the diaphragm.  Therefore, to change the points, the pump must be removed from the vehicle.  Undo the 6 screws, remove the base of the pump, unscrew the old points and start to fit the new ones.  Do not be tempted to replace the roller pin with ordinary wire - the pin is made of a special steel and has been hardened to resist wear.

You will have to turn the diaphragm clockwise whilst repeatedly pressing it until the points just lock solid.  Then back off the diaphragm until the points work again, and finally back off another 2/3 of a turn (4 holes).

With points just breaking, there should be a .030 gap between the lower stop and the body, and a .030 gap between the upper stop and the plastic pedestal.  You can bend the brass stops to adjust the gaps.

(I hope this is clear enough for you.  If not, get back to me.)

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QUESTION: Hey Barrie,  Removed the points and put new points on, removed the base but can't turn the diaphragm  Any suggestions? Thanks, Sandy

ANSWER: You are nearly there, Sandy.  

Hold the pump body in one hand and gently peel the rubber diaphragm away from the metal of the body with your fingers.  Do not use a sharp tool - it could damage the diaphragm. There is nothing holding them together apart from years of contact between rubber and metal. Later diaphragms have a thin plastic membrane between the rubber and the metal. This is part of the diaphragm, so if you have a plastic membrane do not try to separate it from the rubber, but gently peel it away from the metal.

When setting the throw-over I press the middle of the diaphragm with my thumbs.

After setting, you should assemble the pump body dry(no gasket goo) and DO NOT tighten the 6 screws excessively.  Just nip them evenly.  The tiny drain hole in the body should be at the bottom of the pump, and the outlet should be at the top.  

I hope this is all clear to you.    

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QUESTION: Hey Barrie, Got the diaphragm loose but when I turn it the points never lock solid.  I turned it to a point that I can't turn any further but they aren't touching. I'm also confused about how I go about bending the brass stops to adjust the gaps.  Could the top brass stop be preventing the points from locking solid?  Sorry for my delay in getting back to you.  Thanks, Sandy

Hi Sandy.  Maybe I described it badly.  

When you press the diaphragm the points will normally throw over.  Turn the diaphragm until the points will no longer throw over, then back off one hole (1/6 of a turn) and they should now throw over but with a fair bit of pressure.  Once you have found this position back off 4 more holes and they should now throw over with only a little pressure.  This is the correct adjustment, so you can now re-assemble the body to the base.  

The brass stops are the last thing to do.  I just fitted new points to two pumps.  In both cases the top stop did not require any adjustment, but the bottom one was too long and needed a small tweak with some fine nosed pliers.

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Barrie Jones


MG Sports Cars from 1949 to 1980 - Including MGB, MGBGT V8, TF1500, TF, TD and modern Midgets. I also specialise in SU carburettors, Lucas wiring, suspension, steering & brakes.


I have owned my 1955 TF1500 since 1966. Technical specialist for the TD and TF with the MG Car Club T Register. Also owned 20 MGBs and currently own an MGBGT V8. Written 3 books on MGs and produced a DVD on how to strip and rebuild the TD/TF gearbox.

MG Car Club.

Barrie's Notes on the 1953-55 MG TF (author). /=====/ Barrie's Notes on the MGB (author). /=====/ Barrie's Notes on the MGB GT V8 (author). /=====/ The Essential Buyer's Guide to the MG TD, TF and TF1500. (author)

M Phil, C Eng, BSc (Eng).

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