VS commodore Fuel pump draining 0.74a

[tiersum]

argh got ya that makes more sence ill check later cheers

 

[VrWagz1]

I thought the fuel pump fuse went straight to the fuel pump??? The purple wire yeah.
My thoughts is someone has mistakenly hooked somthing up to this thinking it just to be a standard Accesories wire. Eg: they did some testing to find a acc wire and just stumbled on this one and used it.
Is there anything non standard hooked in that might be causing this?

 

[hako]

I thought the fuel pump fuse went straight to the fuel pump??? The purple wire yeah.
My thoughts is someone has mistakenly hooked somthing up to this thinking it just to be a standard Accesories wire. Eg: they did some testing to find a acc wire and just stumbled on this one and used it.
Is there anything non standard hooked in that might be causing this?

Apparently the oil pressure switch powers the fuel pump once the engine oil pressure is up - it's a safety thing so that if the engine stops in a prang/rollover, oil pressure will drop and power to the pump is cut so you don't have fuel spraying everywhere and then....bang.

Yousay: Is there anything non standard hooked in that might be causing this?......aftermarket immobilisers can drain power so that's a good point.

 

[moff_man]

Apparently the oil pressure switch powers the fuel pump once the engine oil pressure is up - it's a safety thing so that if the engine stops in a prang/rollover, oil pressure will drop and power to the pump is cut so you don't have fuel spraying everywhere and then....bang.

Yousay: Is there anything non standard hooked in that might be causing this?......aftermarket immobilisers can drain power so that's a good point.

why is it than when the oil light comes on the car dosent cut out? i drove my car around for a solid week with a faulty oil pressure sensor and i still had fuel pressure, i also disconnected the sensor and it still started, i haven't seen the diagram in a while but are they in series or parallel?

and what i was meaning about the lights if the switch was left in the on pos even tho the lights turn off with the door the bcm for some reason will draw current and flatten the battery. its happened to my car, and since i turn the light switch to off before leaving the car,i haven't had a flat battery in a while. it usually happens over night not a quick run in to the shops.

 

[markovr]

the circuit

but you need oil pressure if the fuel pump relay fails or computer takes feed off relay for the pump to keep working until you get home
If fuel pump relay is not energised ,12v can be fed from oil pressure switch (if engine has oil pressure)through contacts 87a and 30 of fuel pump relay to the fuel pump.....if ecm puts 12v on coil of fuel pump relay then 12v from fuse 23 feeds through contacts 87 and 30 of relay to fuel pump

 

[tiersum]

i do have a aftermarket immobiliser that was installed by a coconut so maybe he has #$%^^&$# something =/

 

[hako]

why is it than when the oil light comes on the car dosent cut out? i drove my car around for a solid week with a faulty oil pressure sensor and i still had fuel pressure, i also disconnected the sensor and it still started, i haven't seen the diagram in a while but are they in series or parallel?

I'm not sure exactly how it works, but I'd guess that no oil pressure + no engine revolutions means the ECU cuts power to the fuel pump. This is indicated by when you first start the car, the ECU primes the fuel pump for about 2 seconds, engine starts and oil pressure builds and the oil pressure switch then powers the fuel pump. If the engine doesn't start and the ignition is still on, the fuel pump does not pump. Otherwise, the fuel pump would be running whenever the ignition is on and the engine stopped. The wiring diagram does not explain what parameters the ECU needs to supply power to the FP relay.
No oil pressure does not seem to cause the ECU to cut power, but no oil pressure plus no engine revs will cut the power.

 

[delcowizzid]

the oil pressure switch is a backup circuit should the relay fail or the ecu goes into limp home mode means the fuel pump will run when oil pressure comes up from cranking so you can get home.