Q. Fuel system?

[monkey boy]

Car briefly lost all power today as if it ran out of fuel. Later on it happened again though this time I ground to an halt. when I tried to restart the car I noticed that the fuel pump ran continuously when the ignition was switched on. Normally it runs for a few seconds then stops untill the engine is started. This led me to thinking that it couldn't raise enough fuel pressure and that either the fuel filter was starving the pump or that the pressure regulator valve was stuck open. Having looked in the Bible I cant find any reference to a pressure switch that stops the pump in the explanation or any of the wiring diagrams. So how does the pump stop when the ignition is first switched on.

[GreenV8S]

It's timed by the ECU - there is no pressure sensor or switch or anything like that. If it runs continually I would suspect an electrical fault upsetting the ECU.

[adiandvic]

could it be the fuel pump relay thats connected to both the ecu and fuel pump isnt it????

Only a guess but I had fuel pump relay issues a while back that caused odd things to happen with the fuel pump

[monkey boy]

Thanks Peter, that makes sense i'v just changed plugs, extenders and leads to cure an intermittent misfire. Just possible that i've run them too close to a sensor or LV cabling and spiking the ECU. Will check today.

[monkey boy]

Thanks Adrian, Ordered two of these relays last week, due in on Wednesday. This was following losing all power in the fastlane of the M4. Didn't know at the time to check rev counter to eliminate ignition relay though think it was the fuel relay. Nice to know that its possible to experience unusual faults caused by these items as they may cure more than expected.