Hello,
good day to every member.
Please am here again for another support.
There is shot of power to the change-over valve of my series 3, is this easy thing I can fix myself?
I have change all the fuses in the car but still not power to the change-over, if I can fix myself, how do I tackle it please?

Thanks

Mike

 

The fuel valve in the boot that switches between tanks?

 

exactly, that is what am talking about boss.

 

The power for the changeover valve goes through the dashboard changeover switch first. Check to see if you have 12v in and out of the switch first. The changeover valve has power when the dash switch is in one position and no power when in the other position. I think the left side is the no-power position but someone might correct me on that.

If you are not concerned about originality you can simply remove the changeover valve altogether and replace it with a brass 1/2" barbed tee fitting. Then both tanks are connected all the time. And you can fill the tanks from either side as they level out.

What year is your car?

Jeff

 

yes, you are right, I used to drive it on the tee but now want to fix the changeover back.

My car is 1985 XJ6

 

The changeover valve in the trunk and the two return valves get 12V "+" from the changeover switch on the dash. Supply to the changeover switch comes from the ignition switch and through the inertia switch.

The ignition coil and dashboard gauges are also supplied from the the same branch of the ignition switch

If the engine starts and runs, and the gauges work, then output from the ignition switch and inertia switch is OK, and the problem is likely to be the changeover switch....or a poor connection along the path

If you have a 12V test light, or a meter, simply check for 12V on the white wire at the changeover switch with the key "on". If no voltage then you have a supply problem upstream of the switch. If voltage is present on the white wire, operate the switch and check for voltage on the white/purple wire at the changeover switch. If no voltage, the switch is faulty.

If you have voltage on the white/purple wire but no voltage to the fuel valves then you have a problem downstream of the switch. A broken connection, most likely.

Note that all three fuel valves get 12V "+" voltage simultaneously. That is, all three should have either 12V "+" voltage or zero voltage, depending on the operation of the dashboard switch

Cheers
DD

 

Doug always says things so much more eloquently than I do.

If it helps, here is how to get the changeover dash switch out. There may be another way to get to it but you can see in this video what it looks like back there.

 

Auto electrician on the car and attach is the state of the switch connector

 

The connections loosen with age. Loose connection = high resistance = excessive heat = melted connector and scorched terminals.



Cheers
DD

 

hi Doug,

Please can you confirm if the two black wires connecting to the change-over all suppose to have power? I thought one is live and one is neutral but these two all have power is that right?

Also looks like the white/violet wire at the trunk where the fuel pump and the changeover are is not connected, could you please confirm where to connect that as well?

Thanks

 

On each of the three fuel valves one wire should be ground at all times. The other will have 12v "+", or not, depending on the position of the dashboard switch

I'm not familiar with a white/violet wire in the area. I suspect you're seeing a white/purple wire....but the color has faded a bit over the years.

The changeover valve should have a white/purple wire connected to it.

Each of the three fuel valves has two black wires which connect to the wiring harness of the car. The valves are not polarity sensitive; you can connect the black wires either way, it doesn't matter

Cheers
DD

 

Hi Doug,
You are right, it is white/purple wire but it is not connected anywhere but it is live wire and we are not sure where to conned that.