no volts on fuel pump fuse

[eduard]

I am dismanteling a RR 3.9 with the 14CUX ecu and have plans building it in my 110.
Most of the electrics have been removed now.
But......I have lost power on the fuel pump fuse, as far I can hear the relais clicks.
I alsoo shortcut the inertia switch.
Can anyone tell me what to do?

Eduard

[Darkspeed]

A specific ECU expert may be able to confirm - but its common for the fuel pump not to be activated by the ECU until it detects engine rotation - thais can be via oil pressure on some old systems or from the crank position sensor on newer systems.

Andrew

[eduard]

Thanks Andrew!
Just checked the fuse box and the connection on the fuelpump with a control light and.... only when the engine starts/rotates then I do have volts.

So the fuel pump has passed, not a big problem as I will have to mount another pump because this one in the tank will not fit in the tank of my 110.

Many thanks from Holland.

Eduard

[Dangerdoc]

I am not sure with a 3.9 however with a 3.5l the fuel pump will not activate until the engine is turning over as this causes the air flow meter flap to open and this makes the connection via the fuel pump relay.

The 3.9 I think uses the hotwire system but just remember that all is not always straightforward and you must keep a very open mind on the electrical circuits as lots of tiny bits make big differences.

The point is keep an open mind and not just look for direct connections or always blame the ECU.

Doc

[eduard]

Doc,

You are right about the hot wire system.

Thanks,

Eduard

[Ian Anderson]

On the hotwire system when you turn the ignition on the fuel pump will run for about 3 seconds. thi will prime the fuel rail

the pump will restart once the engine it turned over and the ECU starts picking up a trigger from the distributer

Ian