Fuel pump not activating? Help needed, please!

[megaera]

I have a bad feeling I am missing the glaringly obvious........but I am having big problems with my fuel pump on a 1984 coupe VX.

The fuel pump will not prime/activate/run when the ignition is on or when cranking. There is power in and out of the relay on the O/S wing. If I supply direct feed from a battery to the grey and black wires in the boot, the pump runs.

Now the bit that is really confusing me. Under the distributor, there is a big block connector. Running with that, there is a connector with a red wire and a green and yellow ( or blue amd yellow???) one. If I unplug this, the pump runs when the ignition is switched on. The red wire goes to the starter - but what does the green/yellow one do?

I have no manuals or wiring diagrams - so I would be very grateful if anyone can shed light on this.......where does the  green/yellow wire go?

I bought the car with a Cobra alarm already installed. It seems extremely complex - with loads of connectors and fuse blocks and a ton of wiring. I would like to rip it out    .......could the alarm be causing this problem? I know I am grabbing at straws at the mo'

Very grateful for any help/hints/suggestions..........

Thanks!

[mtulloch]

That happened years ago to one of my previous VX's, the relay was at fault. First thing to check is;

Does the relay have power?
If you bypass the relay with a link wire, does the pump run?
If not, I would suspect the alarm as the fuel pump & ignition will probably be the most common circuits to immobilise.
You could then run a wire from the switch feed of the relay to the pump to determine whether the relay out to pump feed wire is the issue.

Keep trying, the wiring isn't that complicated.

Cheers.

[lukasdeopalenica]

The electric fuel pumps in VX and i.e versions are probably the same, but probably the activation system is different. On injected models there is a double relay and an intake air flow meter which has a cut off switch to stop the pump when the engine is not revving. Because VX versions have not the AFM they must have any other system protecting from fuel supplying in emergency cases, eg. after an accident.
If I am not wrong it is linked with an oil pressure sensor...

[rossocorsa]

https://www.dropbox.com/s/fpsxhg41dbyue9u/Volumex.pdf?dl=0

Have a look at this, not sure if the answer is there but worth reading anyway.

ps not forgotten about the fabric just haven't had time yet!

[megaera]

The electric fuel pumps in VX and i.e versions are probably the same, but probably the activation system is different. On injected models there is a double relay and an intake air flow meter which has a cut off switch to stop the pump when the engine is not revving. Because VX versions have not the AFM they must have any other system protecting from fuel supplying in emergency cases, eg. after an accident.
If I am not wrong it is linked with an oil pressure sensor...

Yes - I was think there is a cut-off switch, which shuts off the fuel pump if there is an impact etc. i have yet to find out where it is, though!! I suppose it may be possible for this to malfunction and stop the fuel pump?

Thanks for your thoughts!

[megaera]

That happened years ago to one of my previous VX's, the relay was at fault. First thing to check is;

Does the relay have power?
If you bypass the relay with a link wire, does the pump run?
If not, I would suspect the alarm as the fuel pump & ignition will probably be the most common circuits to immobilise.
You could then run a wire from the switch feed of the relay to the pump to determine whether the relay out to pump feed wire is the issue.

Keep trying, the wiring isn't that complicated.

Thanks for your input. I will try your suggestions tomorrow!!!

Cheers.

[megaera]

https://www.dropbox.com/s/fpsxhg41dbyue9u/Volumex.pdf?dl=0

Have a look at this, not sure if the answer is there but worth reading anyway.

ps not forgotten about the fabric just haven't had time yet!

Thanks for the link - excellent info.

I know you have lots going on - so whenever is good for you will be just fine regarding the fabric!!