Fuel pumps

[johngosnell]

I have been meaning to ask about identifying pump problems. when turning on the ignition the left hand pump runs very fast until the carb is primed but if the right hand pump Is turned on it is very slow any thoughts Both checked at different times not just switching left to right.

John

1B1257BW

[cass3958]

I think this might have something to do with the length of pipe to the pumps. The two pipes running from the pumps meet at a T junction just behind the rear right side passengers seat so the pipe from the left tank is longer. When the pump comes on the fuel is pumped up but needs to travel further from the left tank than the right. This would account for it pumping for longer before it is primed but not necessarily slower unless it is to do with pressure of the fuel in the longer/shorter pipe. Have you tried swapping the pumps over to test them and see if you have the same result.

[johngosnell]

No I have not swapped the pumps, but when the car was restored in 2014/15 the right hand pump stuck when we first tried to start her, it has been ok from then apart from the slow run on start up

[cass3958]

It might be an idea to just service the pump. Very easy to do. Remove the pump from the car. Remove the black plastic cover from the top of the pump and underneath you will find the breaker contact points. I did mine only a couple of weeks ago as my pump had remained dormant for about three years whilst I was deciding when to change my ruptured fuel tank. The points were stuck together and corroded. I removed the points and cleaned them by rubbing them on to a piece of wet and dry., replaced them and away she went.
This is a clip on youtube which is about the SU fuel pumps from an MGB but they are the same as the Jaguar pumps.
https://www.youtube.com/watch?v=_VGQPg15-8E
I doubt you will need to go to the extreme of stripping the diaphragm out but it explains how to set up the points.

[johngosnell]

An overhaul of the points is something I can do as I can sit in my chair to do the work. thanks for the youtube I never thought about the length of pipe from the 2 pumps.

John

1B1257BW

[Glyn Ruck]

I believe you could service the pump points from your chair if you removed the pump & worked on the boot floor.