gchristofi
Member
Hi All
I've been chasing an intermittent starting issue with my 1991 Range Rover 3.9 EFi for a while now. Since my car has an LPG conversion, my first port of call was a forum I was already on and some history to the issue can be found in the following post
LPG Discussion Forum • View topic - Range Rover Classic 1991 3.9 EFi - what LPG system is this?
To cut a long story short , after a little fun off road including a bit of deep water, the problem became permanent which has helped me realise why the car was hard to start. I believe there was an intermittent short in the loom causing all 8 petrol injectors to remain stuck open and therefore massively overfuel. Now the short is permanent and the battery runs down overnight and if the petrol pump is left running, the engine overflows with petrol (see the trumpet on number 8 cylinder which had overflowed!!)
Investigated further by removing the ram housing and injector rail and proved that it is all 8 injectors that flow permanently with ignition and fuel pump on. The half plastic bottles all filled in a matter of seconds with the pump on!!!!
I have a Haynes and see that on the 14cux hotwire, pins 11 and 13 of the loom provide the signal to the right and left bank of injectors respectively, and that pin 2 completes the circuit. I'm trying to figure out if the injectors should get a permanent +12v from pins 11 and 13 and are then grounded through pin 2 to pulse, or vice versa? How to best test if the issue is in the ECU itself or in the loom? Am I correct in thinking a short could cause this fault? Could it even be a knackered ECU?
points that may be relevant (or not!)
- EFi system shows the orange ! warning light on dash (not surprising)
- Pulling harness connector at each injector stops the flow at that injector
- Pulling the main relay for the EFi stops the flow of injectors
- Petrol Pump relay is bypassed to a manual switch, hence the pump can be run continuously rather than a few seconds without starting the engine (PO did this to stop unexplained petrol usage when on LPG)
-many sensors are currently disconnected from the loom i.e. fuel temp, stepper motor etc but I don't think this should matter?
Next step for me is to electrically isolate the LPG side of things from the loom and see if problem remains. This all a bit new to me
I've been chasing an intermittent starting issue with my 1991 Range Rover 3.9 EFi for a while now. Since my car has an LPG conversion, my first port of call was a forum I was already on and some history to the issue can be found in the following post
LPG Discussion Forum • View topic - Range Rover Classic 1991 3.9 EFi - what LPG system is this?
To cut a long story short , after a little fun off road including a bit of deep water, the problem became permanent which has helped me realise why the car was hard to start. I believe there was an intermittent short in the loom causing all 8 petrol injectors to remain stuck open and therefore massively overfuel. Now the short is permanent and the battery runs down overnight and if the petrol pump is left running, the engine overflows with petrol (see the trumpet on number 8 cylinder which had overflowed!!)
Investigated further by removing the ram housing and injector rail and proved that it is all 8 injectors that flow permanently with ignition and fuel pump on. The half plastic bottles all filled in a matter of seconds with the pump on!!!!
I have a Haynes and see that on the 14cux hotwire, pins 11 and 13 of the loom provide the signal to the right and left bank of injectors respectively, and that pin 2 completes the circuit. I'm trying to figure out if the injectors should get a permanent +12v from pins 11 and 13 and are then grounded through pin 2 to pulse, or vice versa? How to best test if the issue is in the ECU itself or in the loom? Am I correct in thinking a short could cause this fault? Could it even be a knackered ECU?
points that may be relevant (or not!)
- EFi system shows the orange ! warning light on dash (not surprising)
- Pulling harness connector at each injector stops the flow at that injector
- Pulling the main relay for the EFi stops the flow of injectors
- Petrol Pump relay is bypassed to a manual switch, hence the pump can be run continuously rather than a few seconds without starting the engine (PO did this to stop unexplained petrol usage when on LPG)
-many sensors are currently disconnected from the loom i.e. fuel temp, stepper motor etc but I don't think this should matter?
Next step for me is to electrically isolate the LPG side of things from the loom and see if problem remains. This all a bit new to me
