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MG TD TF 1500 - Fuel pump safety

Hi !
I'm wondering about safety of the SU fuel pump. What happen if the diaphragm becomes cracked ?
I'm affraid fuel comes to contact points which are always sparkling a little.
Ignition hazard isn't it ?


LC Laurent31

I believe the diaphragm is in a sealed environment. Isolated from the points by the casting that contains the inlet and outlet fittings. If it ruptures you do not get fuel, but there is no fuel leakage.

Jim B.
JA Benjamin

I tried to correct the post but it did not take.

There is a weep hole behind the diaphragm. The restriction of the hole should be less than that of the diaphragm shaft going through the body. The fuel in the pump cavity should be limited if the diaphragm is ruptured since there is no suction. It should preferentially run out the weep hole which ideally is located on the bottom.

Jim B.
JA Benjamin

In all my years of working on cars I've never heard of an electric fuel pump exploding. They can continue to pump gas after an accident if a fuel line or fitting has ruptured. That is probably the biggest cause for fuel pump related fires, not point sparking.
TW Burchfield

The "weep hole" is actually a vent for the back side of the diaphragm so there is no pressure backup in that area.

A cracked diaphragm is a rather rare occurrence in a SU fuel pump, the diaphragms that I have seen in all the pumps that I have serviced don't normally crack - most of the ones that I have received that are leaking is the result of extreme old age with old fuel that have turned to jelly.

If the pump was to start leaking internally, there is no real danger of a fire starting since the mixture would be vastly too rich to support combustion. Cheers - Dave
DW DuBois

Watch the episode of myth busters to see what lenghts Hollywood has to go to for the spectacular gas explosions and fires to take place. It was eye interesting. Regards, tom
tm peterson

This thread was discussed between 16/07/2015 and 17/07/2015

MG TD TF 1500 index

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