Are you getting pulses at the coil? The pulses are sent to the ECU for injector timing. If no pulses, no injector action. The pulses are sent from the distributor and amplifier.

 

I did not. Please reply if you find a solution for yours. Good luck.

 

If you just want to throw parts at the problem, maybe start with the distributor amplifier. There is a good step by step troubleshooting routine in the Workshop Manual.

 

Thank you for your answers, I already change the amplifier STC1184 and the plate base RTC5090 without any results. And I changed the ignition coil too
I don't have an oscilloscope in order to check pulses, I have only one multimeter in order to mesure voltage and so on.
I have when I cranck:
pin 39 on the ECU : around 2 volts (the workshop manual said 9.5 +/- 1 V)
Between the R=6.8Kohm and the ignition coil : around 10 Volts

I don't know if it is normal to have 10 V before de resistor and around 2 V just after ???
I checked my resistor and clean connexions, all seem ok.
I tried with a new wire form the ignitions coil to restistor but I have the same result, the injectors did not not fire...
I tried with 2 different ECU => I have the same result, the injectors did not not fire...
I tried with 2 different flow meter => I have the same result, the injectors did not not fire...
I checked my "ground" on pins 27, 40 and 14 and with direct wires to ground => but without results
It seems there is nos ground signal on the exits pins 11,12 and 13

I tried to find with severals months now without any results ....

 

Sounds like you have worked on this a lot. Sorry for the frustration. Here are a couple points to start:
1. A multimeter can detect pulses when the engine is cranking. Easy to see with a meter that has a mechanical needle (any cheap one set to read 12 V). For a digital meter the numbers will start dancing around.
2. Do you have access to the 7 Tests in the Workshop Manual? Preliminary is to check the gap at the reluctor wheel. First test is to remove the center HT lead from the distributor, set it close to the engine block, then check for sparks while cranking.

If we go through the tests, it will pinpoint the problem area. The voltage at pin 39 should be pulsing while cranking and running.

 

Just a precision my vehicle is a RANGE Rover V8 3.9 EFI from 1990.

Ok, I will try to find a multimeter with a mechanical needle in order to see pulses.
Yes I adjusted the gap between at the reluctor wheel around 0.2 mm following the handbook.
I have sparks on the spark plugs, but after crank the spark plugs stay dry without any trace of fuel.


Yes I have severals Land Rover handbooks and I done already several tests :

ECU pin 15 and ground (battery voltage input) => around 12V => ok
ECU pin 19 and ground (ignition switch input) => around 12V => ok
ECU pins 27,40,14 and ground (ground) => 0.04V => ok
ECU pins 2 and 13 (injectors n°1,3,5,7) => 4.4 Ohms => ok
ECU pins 2 and 11 (injectors n°2,4,6,8) => 4.8 Ohms => ok
ECU pins 32 and 25 (fuel T° sensor) => 34000 Ohms => ok
ECU pins 7 and 25 (coolant T° sensor) => 35000 Ohms => ok
ECU pins 1 and 26 => 50 Ohms => ok
ECU pins 28 and 29 => 50 Ohms => ok
ECU pins 3 and 25 (throttle position sensor) => 5200 Ohms => ok
ECU pins 35 and ground (flowmeter) => 0.65 V => ok
ECU pins 34 and ground (neutral switch) => 5V => ok

The other tests below are not in line with the handbooks, but I don’t know the influence :

ECU pin 20 and ground (throttle potentiometer) :
=> closed 0.65V (handbooks said 0.085 to 0.545V) so seems ok
=> open 0.2V (handbooks said 4.2 to 4.9V) so seems NOT ok !
But When I try to start the throttle is closed so the information is ok around 0.65V

ECU pin 2 and ground (relay) => with a test lamp, I have a continuous light but the handbook said only 1s , I don’t know if it is important ? but the fuel pump seems working well.

Main relay pin 87 and ground => 0.7 V (handbooks said 11 to 12.5V) => so NOT ok
But it is explained because I have no ground output on pin 12.

So I think that the injectors don’t fire because I have a bad output on pins 11,12,13, (with 2 differents ECU).

But I don’t know the root causes ; bad input on pin 39 (engine speed pulses) but I changed the plate and amplifier, pin 2 because I have a continuous light and not only 1s…

If you have some ideas ?

Sorry for my approximate English, but I am French but I like English cars, I have got this Range rover, a Defender 110 TD5 and a Austin mini.

Thank you for your help.

 

Okay. That is good information. If you are getting spark, you are getting pulses at the coil, still need to verify at the ECU pin 39, in case wiring is bad, but if it is OK, then you have other problems.

Check fuel pressure at the fuel rail to verify fuel pump is really working well. Maybe flow some gas into a container. The pump should run continuously during operation when the engine is running.

Not happy with the TPS. The signal voltage should rise steadily, smoothly (without bad spots) to near 5 V as it is opened, from closed to 100%. So, about 2.5 V at 50%. Change it if it is bad. 0.2 V when throttle open is bad.

The injectors have 12 V supplied when the key is on, then the ECU provides the ground signal to fire the injector. On some Land Rovers, the ECU also gets input from an anti-theft circuit or module. If it doesn't get the correct signal, then fuel is cut off by turning off the injectors, like you are experiencing. It could be that is the root of your problem. Maybe get a tool called a "noid light" to show if the injectors are pulsing. I am not familiar with the anti-theft interlock circuit, so that will take more researching, there are some write-ups about the "spider" to bypass the anti-theft wiring. I hope this helps. Bon jour.

 

Hello,

I haven’t an anti-theft circuit on my Range Rover.
But I have no 12V on the injectors, because no ground on pin 12 in order to command the relay.

Concerning the fuel pressure, I checked the flow after dismantled the pipe just before the fuel rail. I have a continuous flow just after ignition on. I don’t know exactly the pressure because I have not mano.

This weekend I found a multimeter with a mechanical needle and another TPS dismantle from another Range Rover.
I will try to do these 2 new tests next weekend and let you know.

 

Are you saying the power supply to the injectors is not getting through the Main Engine Control Relay (in the Engine Compartment fuse box)? Is the relay good? Maybe test with jumpers? Jumper the ground to the relay coil, relay should click and 12V should be supplied to the injectors. If not, either the relay is bad or the 12V circuit is open somewhere else.

This theory is somewhat of a guess. I only have access to the 1995 Range Rover diagrams. My '94 Disco also uses the 3.9 EFI. The 1995 Range Rover diagrams show ECM pin 17 provides ground for the Main Relay coil (not pin 12 that you mentioned). It looks like the ground circuit may switch on pin 16, so maybe verify the switched pin is connected to a good ground point (for 1995 the ground point is designated E529 through splice S506 somewhere in the engine compartment). If jumpering ground to the Main Relay works, then next step is to ensure the ground is properly connected to the ECM on the correct pin or pins. I probably should have the 1990 wiring diagrams in order to really help.

 

Are you sure your 1990 Range Rover doesn’t have any anti-theft system?