1987 XJ6 VDP won't start

The last time it ran, it would die a bit after warming up. Now I think the injectors are not firing. I can see each spark plug fire when cranking. Priming it with gas it tries to start immediately. A noid on the cold start injector lights up nice and bright when trying to start but on an injector I get a very faint and irregular blip. The 2 connectors and black ground cluster at the rear of the passenger side of the engine have been cleaned. The resistor pack connector also cleaned. The white with black stripe wire with a butt connector behind the coil causes a click when reconnected with the key on. The fuel pump does run when starting and I even jumped the relay temporarily to make it always run. Brand new battery. Brown wires have 12+ volts. I could not identify the trigger wire running from the amp to the ecu. Any help would be much appreciated.

With the key ‘on’ do you have a solid 12v on the brown/slate wires from the ‘main’ relay? The main relay is the voltage supply for the injectors, ECU, and AFM.

The trigger wire is the white/black wire coming off the coil,as you already mentioned.


Yes. The front brown wire on the relay socket.

I see that you are new here. Welcome!

A very common problem with these cars is a buildup of debris at the bottom of the fuel tanks that clog up the fuel fuel pump and fuel filter. Sometimes water leaks into the fuel tanks around cracked seals in the fuel caps and/or blocked drains at the rear of the fuel filler caps making matters worse.

If this happened to me I would first verify that the fuel pump runs by putting the transmission shifter in Drive of Reverse and turning the key to start while having someone standing by the trunk area listening to verify that the fuel pump runs.

If the fuel pump runs then get a fuel pressure gauge and install it between the fuel rail and the cold start injector with a “T”. Fuel pressure while cranking should be about 40 PSI and about 35 PSI while the engine is running.

My guess is that your fuel delivery system os clogged (very common) and fuel pressure very low. If that is true then you should drain and clean out the fuel tanks and change out the fuel filter to see if that improves your fuel pressure.

Please write back with your questions and progress.


1 Like

Not brown.


Solid brown wires always carry constant 12v


The noid should not be lit with ign with ignition ‘on’, Kim - and flicker while cranking…

It should not be ‘irregular’; the ECU grounds the injectors once every revolution - very briefly, no fully lighting the noid. So the noid should light very regularly, in step with engine engine rpms - but not fully…

Have you listened to the injectors while cranking, using a stethoscope - if triggered the injectors are noisy clicking. If not operating; the fault is either triggering signal missing or lack of power. The trigger signal comes from the ign amp via the one white/black wire on coil neg.

In principle; as ign is working, proved by priming and the click when white/black is connected/disconnected should be from the injectors…

Have you tried starting on the other tank? As Paul says, clogging may occur, ‘usually’ affecting one tank at a time.

That the engine previously died during warm-up is a clue - and engine that cannot idle, cannot start…

xj6 85 Sov Europe (UK/NZ)

Ignition on, dis-and reconnect the bullet connector on the coolant rail that runs from the coil to the ECU and hear the injectors click every third time, that is once per 360°. They see less voltage than the cold start injector by design, hence the dim noid.
Remove air filter and push in the flap to hear the fuel pump running. Listen to pressure building up until the fuel pressure regulator at the fuel rail begins to (audibly) bleed some fuel. I know you did most of that already, so see this as confirmation. Try switching tanks and definitely search for air leaks: if it has leaks in the intake tract it will run on the very fat initial mixture and then lean out until it dies.