Vehicle & Technical > Range Rover

Another RRC not firing (fuel problem)

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Range Rover Blues:
So you have the spark in roughly the right place, the fuel pressure to the injector rail and a good battery.

Check the resistor pack for the injectors (3.5 flapper systems use 5 volt injectors).


If the EFi is working right then the fuel pump should run for one second when you turn on the ignition then go off, it only starts again when the ECU sees the ignition coil signal to say the engine is turning.

You could check the fuel system by bypassing the pump relay next to the ECU so that the pump runs continuously.

paulmmc:
The fuel pump is running full time while the ignition is turned on, so that definately isn't right then! But now i am confused, could it be that the fuel pump is working (as i can see it spraying petrol) but it is not working at full pressure? But surely even with low pressure petrol supply it should fire a bit?

Cheers

Rossko:

--- Quote from: paulmmc on August 24, 2009, 09:32:20 ---could it be that the fuel pump is working (as i can see it spraying petrol) but it is not working at full pressure?
--- End quote ---

That's what it sounds like.  If pressure is too low to return from the regulator, there really won't be much getting through the injectors either.   Sure it's an EFI pump?  Sludge in tank, pump and/or filter?

Continuous pump run may be because the flapper is stuck open a bit.  In the normal course of events, with the ignition on, you should be able to poke the flap to make the pump run and release it to make it stop.

paulmmc:
It is definately an EFI pump as it came out of the same donor car as the engine.
Where would i find the 'flapper'? The only one i can think of is in the air intake?

Rossko:

--- Quote from: paulmmc on August 26, 2009, 08:23:22 ---Where would i find the 'flapper'? The only one i can think of is in the air intake?
--- End quote ---

That's the one, if you have the 3.5 type of EFI system.   The flapper carries a set of contacts for the fuel pump, so that the pump won't run unless the engine is turning (drawing air).
You seem to have continuous pump run which suggests something wrong there

BUT

with a running pump you should have fuel spilling back in the fuel return line, or pressure is nowhere near high enough to inject.  Focus on that for now.   A blockage in the rail is really unlikely, a gummed-up regulator is going to prevent fuel return (this would lead to overpressure, but I doubt prevent firing).  My guess is pump is too pooped to make enough pressure, or possibly burnt pump relay isn't delivering enough voltage to drive it fully, or scabby earth.

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