XJ6 have fuel and spark but won’t start

XJ
1

Hey guys,

Got an 85 XJ6 that won’t start. Car drove beautifully about 2 months ago until I was at a stop sign and car just stalled while idling. Had been driving around for 10 min and it was idling perfect and then the revs just dropped like a fuel starvation issue over about a 30 sec timeframe and eventually died. And hasn’t worked since. And with work, kiddos, and traveling have only been only able to focus on it a day here or there. But at this point probably have 3-4 days in it.

I originally tested for spark and had some so moved to fuel, but later retested and lost the spark. So originally with spark I went to verify fuel, I checked fuel pressure, right on the money, checked fuel injector pulse with a node light and when initial cranking would get one blink but have numerous tests eventually didn’t get any light blinks. Followed Roger Bywater write up on his website and checked the air flow meter inputs at the ecu and didn’t see any so replaced the air flow meter. But during reading his write up saw you should check to verify spark/ignition before working on fuel issues. So I check spark again and had nothing. So tracked down a bad distributor pickup and replaced it with a working used one and verified the resistance to be within spec. Now I am getting spark at coil and spark plugs. And now the fuel injector node light is blinking. But it won’t start. It won’t even hiccup or stumble. So at a loss of what to do next. Open to all suggestions

I have swapped out the following components with ones that were working when removed from another car 10 years ago. Only next thing to do is swap back the old parts.

-ecu
-coil
-ignition amplifier
-air flow meter
-distributor pickup (tested and original was bad)
-getting good fuel pressure
-getting spark at spark plugs
-injector node light is turning on/off
-pulled spark plugs and looked good

-Scott

2

Have you checked, after non-start cranking, that the plugs are wet, Scott - indicating whether or not fuel is actually getting there? If ‘yes’ you likely have an ignition problem - the sparks may be too weak to ignite…?

If ‘no’; remove the plugs and ‘dram’ each cylinder with a teaspoon of fuel - replace plugs and crank. If fuel is the problem; the engine will fire up and run briefly - indicating ign is working properly…

It will not necessarily identify the problem, but may point you in the right direction…

Frank
xj6 85 Sov Europe (UK/NZ)

2 Likes
3

I had a problem like this and i had spark with the check spark plug lights and it just was not enough spark. For me it ended up being the distributor cap/ rotor after I changed that. She fired right up. I had to learn the hard way that spark is not a yes / no but also has a how good of a spark!

1 Like
4

Indeed, Max - the spark should be tested with a spare spark plug, triple gapped to simulate pressure condition in the cylinders. Strong and blue means ‘good’ - but the engine may still run with a weaker spark…

Using other methods to check spark is even more uncertain…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)