Well, I have recently been plagued by fuel faults, mainly caused by crud
in one tank. However, the valves have also been playing up.
The way the three valves work is like this.
Changeover valve in boot. Unenergised is directs the flow from the lh
tank to the fuel pump. Energised it directs flow from the rh tank.
Lh return valve (in lh rear wheelarch under a cover). Unenergised it
allows return flow to the lh tank. Energised it shuts flow off.
Rh return valve (in rh rear wheelarch). Unenergised it shuts return
flow off. Energised it allows return flow to the rh tank.
All three valves are wired in parallel. When the selector switch is in,
the valves ar unenergised. Selector switch out puts 12V to the valves.
The return valves in particular are prone to failure, but are not too
expensive (25UKP each). However, if your fault is intermittent, I would
suspect the connections to the wheelarch return valves. The wires run
to a plastic cover plate in the rear of the wheelarch. Inside that they
join to the loom using those daft Lucas connectors. They are prone to
corrosion. So find the wires (you may have to take the metal cover off
the valve), and pull them out gently. They will come out of the cover
plate, and bring with them the hokey connectors. Pull the bullets out
of them, and clean everything up, or splice in decent connectors.
If that doesn’t sort it, tell us exactly what tank fills from which, and
what position the switch is in when it does this. Armed with that we
should be able to figure out what needs replacing.
Craig> -----Original Message-----
Of Mr. Michael D. Fatsi
Sent: 23 March 1999 15:14
To: XJ Lovers
Subject: [xj] Fuel Changeover Switch
My wife tells me that (on her 89 SIII) occasionally the fuel seems to
travel from one tank to the other. Example: both tanks will be half
full, then suddenly one tank is full and the other nearly empty. Since
this only has been occuring sporadically I haven’t done anything about
it. Yesterday she notcied that theee car stumbled and nearly stalled,
untill she switched tanks.
My question: could it possibly be anything else but the change over
switch? I think not but I could always use other opinions.