Hi all, looking for help with a non start fuelling issue. Have a 1993 D1 V8i EFI auto with cats. Drove home fine, parked up and then tried to start next day but pump will not prime at all. With ignition on position 2, there is 10.17 Volts at the pump. Fuel pump relay will not activate. It was replaced with a new unit and same result. Also, tested the relay with a battery and it operated as expected. There is a High signal (12+v) to both pin 86 and 85 on the fuel pump relay. Main relay has also been tested. We have bypassed the relay, and the pump operated so the assumption is the system downstream is fine, as is the pump. It appears that the ECU is not sending the correct high low signal to the pump relay. Other functions on the vehicle are working, so I’m not leaning towards an ECU fault. The only fault I can find is the MAF is showing 0.01 volts on ignition 2 position. Is it possible that a faulty MAF could prevent the ECU operating the fuel pump? If not I’m all out of ideas.

 

Check the Roll-over switch on the pass side firewall (under the Hood) Mine the connections were burnt/corroded and made partial contact. I chopped the wires and tied them together the problem went away.

 

I have tested the inertia and bypassed it as well with no luck. Same symptoms

 

If the fuel pump relay is not activating, either the ground circuit is faulty (open circuit), or the ECM is not sending the signal (ground signal to activate the relay). ECM not sending signal could be anti-theft logic, or bad ECM. Does it start when the fuel pump relay is bypassed?

Rusty or corroded ground connections are a common source of electrical malfunctions. Maybe check the main grounding points and polish them up.

 

the engine will not start when the pump is bypassed, will turn over. From my research the 89 to 93 jays didn’t have any sort of immobiliser, do you know if this is correct?

I will certainly check grounds

 

you likely need one of these - I have a near new one for $150
GENUINE LAND ROVER Fuel Pump Relay YWB100820L Land Rover Discovery Defender 90

 

You mention the pump was bypassed. Did you mean the pump relay? If the pump is running and the engine is crank/no start, then there is probably no spark too. Fuel/air/spark all at the right time for engines to start and run. Find out which is missing (usually fuel or spark, sometimes both) then go from there. I have a '94 and '96, but don't know details about immobilizers. Hopefully I won't need to learn.