Hello,

I have a 3.9 discovery which is running very rich on petrol, on gas it is fine. It is an older gas system, with no lambda or throttle inputs or that.

On either fuel, it idles a wee bit rough, is that common?

On petrol, i have changed the stepper motor, checked the resistance of the fuel and water temperature sensors and they are 5k and 9k. I have set the throttle pot as per rpi instructions and calibrated the air meter, disconnected the ecu for a wee while to reset it but with no joy. I have even changed the tune resistor to elimate the lambda probes but it is still very rich.

The fuel pressure is 28psi. I am undecided whether to change the ecu or the air meter - any other ideas? I swapped the plugs on the petrol temp and the water temp sensor but with no joy. Please help