SU FUEL PUMP & REPAIR

Note: Early E-Types and Mark 10s had submerged fuel pumps inside the gas tanks. Later E-Types were equipped with external SU pumps similar to the above.

The SU fuel pump has a terrible habit of malfunctioning if it is not serviced regularly. There are three main causes:

Bad or rusted ground connection especially on XKs with Positive Ground.
Arcing or sticking contact breaker points (see maintenance below). One way to eliminate the arcing problem is to add a simple suppression diode of 3 Amps/50 + Volts available from Radio Shack or similar electronic stores. For complete "how to" instructions to add a diode CLICK HERE .
Dirty or clogged filter

SU PUMP MAINTENANCE

The normal maintenance of the SU LCS type pump Consists of cleaning the pump filter and checking that the contact breaker points are clean and correctly adjusted.

Before attempting to remove the filter the inlet union to the pump should be disconnected and connected to a length of rubber hose the other end of which should be held at a higher level than the petrol tank. This procedure is necessary to prevent draining the petrol tank which is at a higher level than that of the pump. With the inlet pipe thus removed, remove the 2 BA screws securing the lower lid C (see FIG 2:1) to the pump body and remove the lid and filter. The filter should be washed thoroughly in petrol and blown through to ensure that all the sediment has been removed. Rags should never be used on this filter. Clean the lower lid C and remove all traces of sediment. Replace the filter and lid C ensuring that a new gasket is fitted between the lid and pump body. Reconnect the inlet pipe at the pipe union.

The contact breaker points may be cleaned after removing the bakelite cover by placing a thin piece of card or clean paper between the contacts and pulling it backwards and forwards.

To check the contact breaker gap the spring blade V should be held in contact with the moulding S and a feeler gauge placed between the white fibre rollers on

the outer rocker and the pump body. The clearance should be .030 inch. To adjust the contact breaker assembly the outer rocker should be pressed to coil housing in this position the contact blade V should just rest on the small ledge projecting from the main face of the bakeJite pedestal, If it does not slacken the attachment screw of the spring blade, swing the blade clear of the pedestal and then bend it down slightly so that when repositioned it rests lightly on the ledge. Check that the original clearance of .030 inch between the outer rocker rollers and the pump body is maintained, If this clearance has not been achieved repeat the procedure until it does.

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Comment by Charles Russell on June 9, 2012 at 11:34pm: Rafe I just went around the problem and installed a Mallory low pressure pump with a low pressure activation switch.

Comment by Charles Russell on June 9, 2012 at 11:35pm: sorry meant oil pressure activation switch.

Comment by Otto Mueller on June 25, 2012 at 1:55am: Charles, I have the same type of pump by FACET on my engine, with the loss of oil pressure cut-off switch.

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