Xj40 spark but no start

Hi! Trying to fix my xj40-94 which will not start. It ran just fine before. But efter a unusual cold night It wouldnt start. A few days later it starts rather reluctantly with jumpercables and some persistence. It ran fine for a few minuters before giving up under throtle untill it completly died with Smoke comming out of the exhaust. Oil and coolant level apears to be good.
I’ve checked the crank position sensor. No short on any of the cabels, sensor messured 1,35k ohm and the teeth looked okey.
Sparkplugs, cable and coil apears to be ok. It delivers spark, and I think I can smell fuel. Fuelpump buzzes and whatever fuel device is under the bonnet also buzzes.
It wont even run on starter fluid. I’ve checked compression on 6 5 4 before running in to the problem of the adapter loosening from the tool instead of being unscrewed from the cylinderhead. All three read about 150 psi or sligthly over.
When cranking the enginge and then stoping it Will sometimes ignite one or two cylinders.
I’m almost out of Ideas, and the vcm wont show any errors. Is there anyone who can point me in the right direction to solve this problem?

I would first suggest you check the fuel pressure. Not sure what your buzzy under the hood device is ? Fuel pressure regulator ? If that is not your problem, then check your coolant temperature sensor resistances, the connector and the wiring for broken, fraying or shorted wiring.
SD Faircloth www.jaguarfuelinjectorservice.com

But shouldn’t it ignite on starter fluid even if there is no fuel? Haven’t seen any wires that looks damaged. Or any corroded connections. And is there any reason a faulty temperature sensor might prevent it from starting, or is it part of a possible diagnosis?

You indicated smoke out the exhaust and you can smell fuel. I took that as possible overfueling…flooding the engine. Starter fluid would just exacerbate the overfueling. If the coolant temp sensor is faulty…the general effect is it sends a faulty voltage signal to the ECU…which the ECU interprets as a cold engine, and the ECU increases the pulse width on the injectors to add more fuel…flooding the engine. SD

You can also try to clean the mass airflow sensor. When my car’s engine was running rich, I unplugged the MAF and the engine didn’t die. I also had a CEL and a FF23 code.

Try flooring the accelerator pedal and cranking, if the engine is flooded this shuts off the injectors, you will need to crank for quite a while before the engine will be ready to fire. Once it firs just release the pedal and it should idle.

My usual suggestion - try a spare rotor - also check cap and plug leads.

yellow spark no good, big blue is what you want …rotors are notorious for going high resistance.

I would start with a fresh, fully charged battery before doing ANYTHING else.


Continuing the discussion from Xj40 spark but no start:

Sorry for not getting back sooner. I’ve done som more troubleshooting without any success. I live in Sweden so I checked autodoc for parts, bought som filters and ignition parts cuz why not. Started today at first crank when I replaced the rotor. Had triple checked that there was spark on all plugs with a testligth, but it was apparently not strong enough. But if anyone else buys from autodoc I can’t recommend their sparkplug leads. They don’t seal at all around the sparkplug well. But the distributor cap fit even better than original. And the rotor fits just fine.