Astra fuel pump runs for 10 seconds, or so, then stops?

Had a problem with an G reg Astra. Haynes says the pump is fed by a relay
powered from a control unit of some kind. Does anybody know what might cause
the fuel pump to stop running after 10 seconds. I think the car was a GTX or
something like that. Trying to assist a friend.

 

The relays have a habit of dying, try whacking it with a screwdriver and see
if it comes back on. Unless you mean it runs for 10secs when you switch the
ignition on, but not start the car, in which case this is just the pump
priming and is normal.

I think you mean GTE not GTX btw. if its a 16v then the above dosen't apply,
as they don't prime, but I think the 8v's do.

 

A few things spring to mind.
Possibly the fuel pump relay is faulty.
Is there an after-market immobiliser fitted?
Faulty ECU maybe.
Check for a live at the fuel pump to see if it grounds when the pump cuts.

 

Thank you for replies.
There was an immobiliser fitted and we thought it may be to do with that.
Trouble is you can never work out what is going on. Any idea where the relay
for the pump is please? Hopefully the car is now gone but, while my garage
friend just wants the car to go, I would like to know what the fault really
was. Relay is fed from box, which I assume is the ECU.