I have an all original 1977 Jaguar XJS with 18665 miles on the odometer. The car has not been driven since 1993.

I’ve replaced the ignition coil, spark plugs and wires and visually checked the entire ignition system. I have what seems to be adequate spark.
I’ve cleaned the fuel system (including the fuel tank), replaced the fuel filter and pump, and now have good fuel supply and pressure (31.2lbs) at the rails.
However, the engine will not start. It does seem to fire a couple of time when I first attempt a start, but it will not run.
I have no fuel injector action at all. I suspect the initial firing is from fuel supplied by the cold start injectors.
I checked all injector circuits by using a small 2.5v bulb. There is NO injector action at all.
The injector wiring harness and connectors have been checked OK.
I’ve checked the pulses (at ECU connector) from the injector trigger board OK.
Power Amplifier
There is both a good GROUND and 12VDC to the injector power amplifier. Also, I checked the voltages, ground, and resistance readings within the power amplifier OK.
Question: Is there a way I can test (trigger) the power amplifier?
ECU
There is both a good GROUND and 12VDC to the ECU pins .
The continuity (OHMS) from trigger unit (pins 21, 22) to ECU (pins 21, 22) and the ECU (pins 4, 5) to the power amplifier (pins 11, 12).
Questions: Is there a way I can test the ECU injector pulse output (pins 4, 5)?
My test equipment is a high end Fluke Digital Multimeter with record and graphical output.

 

Firstly welcome aboard.

When time permits, please do an intro in the "New members area".

Under the distributor cap, you have a trigger board. THIS supplies the injector pulse to the ECU of that D-Jetronic system.

In the heel of the rotor is a MAGNET.

As the magnet passes over the trigger board, the switches imbedded in each end are "activated", and the injectors, inject.

There are 2 versions of that trigger board.

1) 3 wire unit, with reed switches imbedded. VERY unreliable.
2) 4 wire unit, with hall effect sensors imbedded. Extremely reliable. The 4th wire is an Ign +ve of solid 12v (not ballasted).

NO fancy stuff needed to test these babies.

For the 3 wire unit. Take a magnet on a stick, pass it over the ends of the trigger board, and if your hearing is GOOD, you will hear the switches "click".

For the 4 wire unot, Ign ON, pas the magnet, injectors should click. You want hear hall effect sensors.

Some replacement rotors have NO magnet, whoopee, they are for the Carby V12.

The magnet is a different shape for the 3 and 4 wire boards, NO idea why, it just is. I forget now which shape is for which board. They are "round" and "squarish".

That is where your problem will be I reckon. Those ECU's and the Amplifier unit are as tough as nails, and I have never seen a dud yet.

The running you are seeing is the fuel from the cold start injectors.

 

Thanks for your input.
The rotor arm is new and I have traced the trigger pulses back to the connector at the ECU input. So, I'm assuming the trigger pulse is OK. Do you know of a way to check the ECU trigger from the ECU to the injector amp connector?
Hope you can help.

 

I am looking into the same thing. My 78 runs great for about 20-30 miles,then starts to break up under load and eventually stalls. After it sits an hour or so it starts and runs like there never was a problem. I have pretty well ruled out ignition, I have a new fuel pump so I do not believe that is an issue. I will let you know what I find on my end. It may be a while, November in Michigan is not a great time to get the classic car out.

 

Not sure on the "pulse tracing", as electronics is not my strong, or weak, field.

I would be doing a continuity test on each wire for starters.

By then someone with better 'tronics talk may slide by.

 

I have had a few of them issues.

If your car still has the Opus amp in the middle of the V, it needs to be moved outside the V. Heat causes issues with the Poer Resistor contnuity after about 30 miles.

There was a kit to do this a while back. Some report success by simply reattaching that resistor to make a better contact with the unit.

I replace that system with a Crane system.

 

[QUOTE=Grant Francis;1347630]
If your car still has the Opus amp in the middle of the V, it needs to be moved outside the V. Heat causes issues with the Poer Resistor contnuity after about 30 miles.

There was a kit to do this a while back. Some report success by simply reattaching that resistor to make a better contact with the unit.
[\QUOTE]

Further to Grant's advice, if you google ReOpus, that is a kit designed to fix the tiring out original. I believe SNG also sell a replacement item that effectively updates the Opus system to the more reliable later system.
Greg

 

Hi there,
Does this problem occur only one time after initial startup? Or does it repeat every 20-30 miles? I'm thinking it might be starving for fuel. In addition to the fuel filter under the hood, there is a fuel strainer on the fuel pickup (suction line) within the small holding tank (sump) located in the trunk. From what I understand, this thing can get plugged over the years. I replaced mine when I clean the entire fuel system.
Good luck.

 

Thanks for your input. I just purchased a new trigger board and will install it in the next couple of days. I'm not sure if the original is in fact the problem, but based on what I've heard, I'm going to replace it now.
Thanks

 

Starving for fuel, maybe.

Remove the fuel cap, NOT having a full tank is wise here. Go for a drive, OK, longish to get to where it plays up, and observe if you get further down the path.

Fuel tank venting, or lack of, will stop the gravity feed from the main tank to the sump tank, then the pump starves for fuel, and the engine dies.

Wait a few minutes, things equal out, fuel gravity flows again, and away it goes until that vacuam point is reached once more. Some early XJ-S cars had the tanks implode due to poor ventilation.

 

Thanks. I already have a Crane system. It was poorly installed. I have been through the distributor, relocated the Crane amplifier to the right side of the engine compartment, and replaced the original ignition resistor with an aftermarket resistor, also mounted outside the Vee. When I was sitting on the side of the road with few tools I was able to verify I had good spark out of the coil.
On my last drive, after replacing the fuel pump, it ran great...for about half an hour, then started cutting out under load. Still ran good at low throttle, low load conditions. Based on Kirby Palm's book, I have ordered the updated surge tank pickup filter. I have previously cleaned the surge tank and filter. It did not seem too bad, and did not make a difference as far as I could tell. I will be putting a fuel pressure gauge on so I can monitor it while driving, and collect tools to monitor injector pulse, and I suppose drive it until she drops, and see what I have.