1984 XJS Injectors not firing

Well yes but I’m British as well :innocent:

Thanks for the info i’ll do the best i can fingers crossed… :kissing_smiling_eyes:

A constructive and informative conversation thanks, Clive.

Deserter :relieved:

Long time ago and it was a parental decision, am I excused? :innocent:

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Hi Paul thanks for the comment. Most brit’s are still in bed at 4.36 am the other 4.36 is afternoon tea with jam and clotted cream scones. I hope all is well in South Carolina Regards Clive :shushing_face:

Is “parental decision” code for “deported on a prison ship”? :stuck_out_tongue_winking_eye:

Nah thats the big island next door.

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Well we have some good news and some bad news your light bulb trick worked fine that was the good news. … The bad news is no current dead dead dead so what do I do now ??

No current where, how?

From the Lucas ignition amplifier to the ECU in the (boot) sorry trunk therefor no fuel from injectors dashed poor show chaps.

Clive,
What is the history of this car? Did you purchase a non-running car that you are trying to get running again? Or did you own this car for a while and drive it regularly without issues and then all of a sudden the engine stopped running? Did anyone work on any part of this car prior to the current problem? If someone did work on this car, what exactly did they do?

Paul

Purchased as a non runner last September I have been a chef all my life and now I am 85yo I wanted to do something different the last owner had lots of people poking around in the engine compartment to no avail I have had it running but then when you turn it off It will not start again. I am at a loss at the moment I have done a lot of work replacing and renewing parts but this has rely got me.

This cable sends a pulse to the ECU so the ECU knows when to fire the injectors, no real current there.
We need more info on what is wrong and on what you have done already and you need to determine if it’s spark or fuel that is the problem.
Regardless, I would start by changing the GM module inside the Amp.

PS
Put all your info in your profile so we know what we are talking about.
Good luck.


clive_williams

Paul_M_Novak

12h

Purchased as a non runner last September I have been a chef all my life and now I am 85yo I wanted to do something different the last owner had lots of people poking around in the engine compartment to no avail I have had it running but then when you turn it off It will not start again. I am at a loss at the moment I have done a lot of work replacing and renewing parts but this has rely got me. I have had the fuel rail off all clear replaced fuel pump and filter drained and cleaned fuel tank replaced with new fuel. All the injectors have been checked and have a good spray pattern all the seals have been replaced, power to each injector has been checked and all are getting power. the Lucas amplifier has been rebuilt with new module. Fuel pressure fittings have been replaced there is fuel to the rail injectors are in good shape and are getting power but will not squirt. :sleepy:

Purchased as a non runner last September I have been a chef all my life and now I am 85yo I wanted to do something different the last owner had lots of people poking around in the engine compartment to no avail I have had it running but then when you turn it off It will not start again. I am at a loss at the moment I have done a lot of work replacing and renewing parts but this has rely got me. I have had the fuel rail off all clear replaced fuel pump and filter drained and cleaned fuel tank replaced with new fuel. All the injectors have been checked and have a good spray pattern all the seals have been replaced, power to each injector has been checked and all are getting power. the Lucas amplifier has been rebuilt with new module. Fuel pressure fittings have been replaced there is fuel to the rail injectors are in good shape and are getting power but will not squirt. :sleepy:

You need the ignition amplifier to reporting the engine is turning to the EFi before fuel will be injected.

The quickest test is to fumigate the intake with petrol (or other similar combustible) and see if the engine fires.

Is there HT voltage from the coil, or HT leads?
Does the tachometer needle flick when cranking?

You can check for the coil being switched by the amplifier just using a test lamp connected between the coil -ve terminal and Gnd.
When the amplifier makes and breaks the shunt to Gnd the lamp will flicker on/off.

If the lamp flickers, check the resistor between the coil lead and the white lead to the EFI.
If no flickering check the hall effect sensor has resistance as specified (possibly about 300 Ohms) and actually generates a small AC voltage as the rotor passes it.
If the sensor does create a voltage, but the amplifier isn’t shunting the coil to Gnd check power and Gnd and wire continuity, after that it’s an amplifier fault.

image

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Solution/test number 1 ignition amplifier rebuilt with new mo-dual.
Solution/test number 2 engine fumigated will not fire.
Solution/test number 3 there is HT voltage yes the tachometer flicks.
Solution/test number 4 Test lamp connected one to ground one to negative on coil ignition on lamp on crank lamp dims but no on/of.
Solution/test number 5 Hall effect sensor ?? I am not clear as to where and what this is.
Thank you so much for your input my kindest regards clive

  1. New doesn’t mean it is functioning, needs power, Gnd and signal from sensor. It could also be duff.
  2. Ok. Expected, so this is an ignition fault.
  3. What voltage at the plug leads? Have you tried a timing light? Tacho flicking probably indicates the Amp is switching to gnd, but could just be battery voltage spikes when cranking.
  4. It should flick on/off due to the low speed of pulsing. Suggests amplifier not providing on/off shunt to Gnd.
  5. Hall effect sensor is the sensor inside the distributor. It’s just a coil of wire so creates an Ac voltage as the magnetic fingers of the rotor pass it.

Check the resistors in the amplifier unit are in spec, have good contact and are passing voltage.

The Zener diode is probably only to leak off any unwanted voltage spikes from the coil as it fires.
What voltage is present on the Coil negative lead, that should be controlled by the Zener diode when the amplifier is open circuit…i.e. when the hall effect sensor isn’t passing Ac voltage due to engine revolutions.

It would be worth checking the timing isn’t 180 degrees out.

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Correction the tachometer does not flicker.
clive