Jump to content

Fuel in sump of pig

Adam Elkins

Recommended Posts

The pig has started to run very lumpy, revving one minute cutting out the next.

Then i noticed the sump is full of fuel.

My first thought was the fuel pump diaphrams have perished, so took the pump to be tested and was told all is ok.

I was told that something is sticking open in the carb flooding the engine and the fuel is getting past the rings.

is this possible? I would have thought if it was flooding the boars then it would'nt start,but it starts on the button.

Link to comment
Share on other sites

If it's coming from the carb, take it off. There are only 4 x 9/16 nuts & look in the inlet manifolds to see if you are awash with fuel. I once fitted a new foat to find that it sunk as was not quite fully soldered together.


But if it starts on the button. I would have thought your original suspicion was correct that it is a failure of the main diaphragm in the David fuel pump. If that goes it will drain into the sump. It can't drain externally as it was intended for wading. There is an unofficial mod to allow it to drain to ground in the event of failure, but then you can't go paddling!


Who tested & how did they do it? Were they testing for pumping action alone rather than leakage? There must be some pumping action still to allow the fuel to get to the sump. I would dismantle it & have a look inside for yourself. Its fairly straightforward inside. You can modify the diaphragm from a Series 2 or 3 Land Rover. Same diameter & holes in the right place even.

Edited by fv1620
Link to comment
Share on other sites

A local classic car restorers called TT tested it not sure what they did.

This was the official test rig.


There was a simpler test rig. If you could operate the level at the rate of 160 impulses per minute it should prime itself in 30 secs & lift fuel to a height of 3ft 6in & deliver 1/4 gallon in one minute.


what kind of mod do you have to do to a landrover diaphram to make it fit?

Some years since I did it. But the lid has passive diaphragm to smooth up the effect of impulses. Lift out the main diaphragm & compare it with the Rover one. As I recall the Rover one has a central spindle that has to be removed & this releases I think large metal washers on each side of the diaphragm. I'm pretty sure it is exactly the same size & the peripheral holes are in the same place. I can't remember quite how the David pump diaphragm is laid out, but I think you can take it from there.



what kind of oil should i use?


This was originally specified as OMD-110, this became obsolete then OMD-75 used (SAE 10W/30) it was replaced by OMD-85 (SAE15W/40) & then replaced by OMD-80 (SAE 10W/30).


I may have got the sequence of obsolence wrong, but the multigrades were only used due to obsolecence of OMD-110.


It is obtainable so use SAE30 engine oil. Remember the gearbox also uses this oil, not OEP-220, EP90 etc

Link to comment
Share on other sites

Our Humber 1 1/2 T with breakdown crane went out to pull in a 10T tipper on a rigid bar (empty, but it could just about cope with a loaded one!!) and gradually lost power, eventually stopping.


When the driver lifted the bonnets, he saw petrol coming out of the dipstick tube - that was a lift pump diaphragm failure, and I'm amazed the engine didn't blow up what with all those fumes in the sump :shake:

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...