Series 3 V12 - Intermittent Fuel Pump issue.

[B123MWV]

Series 3 G reg V12 saloon: Intermittent Fuel Pump issue.

I replaced the fuel pump and fuel filter yesterday after a suspected fuel pump failure.

Initially, no start. Fuel pump didn’t spin up under ignition. Then after a few goes, it came to life, but only for five minutes or so, then the pump just stopped, obviously followed by the engine.

Few more attempts and it would try and spin up, I could hear it, then it would fail to send fuel to the engine. Then with other attempts, randomly it would spin up and run perfectly for five minutes or so before just stopping again. Connections to the pump are are sound.

Worth noting, when I replaced the fuel filter the contents were quite orange so I suspect a rusty tank? Could this be the problem? Could it be the relay (I’ve got a new one ordered) or is it something less obvious, more electrical gremlin-like? Any clues or shared experiences appreciated thanks..!

Matt

[Tintin]

Hi Matt

Does this mean that you got the car back in the end? If so that's fantastic news! I'm sure we would all be interested to hear the story!

Your pump issue sounds like filth in the system - a good clean out and flush through would be my personal starting point.

Robbie

[B123MWV]

Hi Robbie,

Unfortunately not mate, see my update in the 'stolen' thread.
This is a new one, partly bought with the paltry (and tardy) insurance payout.
I don't think the old one will ever see the outside of a garage again unless its in pieces...

Cheers for advice, by clean out, do you mean drop the tanks?

MB

[Tintin]

Sorry to hear you didn't get it back.

The state of the old filter does suggest contaminated fuel - perhaps rust from water sitting in the bottom of the tank over the years. So if it was me, I would remove and clean the tank, check the pick up filter and flush through or replace the pipework. Failure of the pump to run may well be electrical, but a clean system is a good starting point.

Old Timer has given me good advice in the past on fuel systems - I am sure he will be posting soon to offer more helpful suggestions.

Robbie

[oldtimer]

Hi Matt,
I have read through the thread a couple of times and as Tintin has suggested I would be along soon. I've just been having a read of my Series 3 workshop manual and the fuel system is somewhat different from the Series two V12 on carbs. So we need to work through slowly to work out the sequence of operation.
Tintin , according to the fuel system layout it employs three of those fuel valves that I loaned to you.
Matt. I need to study this further and then suggest to you a series of checks in a sensible sequence but it is getting a bit late even for me.

I shall be back tomorrow