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MG TD TF 1500 - which fuel pump diaphram

i am going to replace the diaphram of unknown age in my fuel pump. i see moss sells 3. original, replacement pump mfg after 1985 and another for shaft length 15/16". i assume my pump is a replacement hung on after 1985, but how do i tell? thanks for the help. regards, tom.
tom peterson

ok, that is shaft length 2 15/16" regards, tom
tom peterson

Tom - You can scratch the diaphragm with the 2 15/16" spindle (that is for a high pressure long body pump which you don't have in a TD). There is really no way to determine which type of diaphragm is correct for your pump without disassembling the pump and looking at the armature on the diaphragm or the core in the coil. The pre 1985 low pressure pumps have a diaphragm armature that is flat, while the post 1985 diaphragm armature that is stepped (see attached photo) The coil core in the pre 1985 low pressure pumps is about 1/2" diameter, while the core in the post 1985 pumps is 3/4" in diameter. Unfortunately, the diaphragms carried by Moss Motors for the post 1985 pumps is not really correct. While the diaphragm carried by Moss Motors will fit in the post 1985 pumps, it is a diaphragm designed for the high pressure pumps and has a stiffner interposed between the diaphragm material and the armature. In my experience in restoring the pumps, using a diaphragm designed for the high pressure pumps do not work properly in the post 1985 low pressure pumps, nor is it the one that comes in the post 1985 low pressure pumps from the manufacture.

I would suggest that you disassemble your pump and see which kind of a diaphragm is in it and if it is a post 1985 pump, e-mail me at the above address and I will work with you on seeing what we can come up with. Cheers - Dave


David DuBois

thank you david! when the driving season ends here in illinois, i will be in touch. regards, tom
tom peterson

Tom,

There is a quick way to determine which pump you have.
The thread of the hole for the ground screw was changed on the post 1985 pumps. I don't remember which way, either from 2BA to 4BA or from 4BA to 2BA. Dave D. may be able to tell you this.

John


J Scragg

John - Thanks for the reminder - yes, the post 1985 pumps did change from a 2BA to a 4BA ground screw. For those who are not familiar with the British Association machine screws, a 4BA is about the same size as the American 6-32 and the 2BA is about the size of the American 10-32. Cheers - Dave
David DuBois

This thread was discussed on 06/09/2010

MG TD TF 1500 index

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