The XJ6 was running a bit rough so I pulled the plugs and found one not firing. I then pulled the injector to that cylinder to inspect it and replaced the 3 1/2 inch fuel line while I was at it.
Now I'm getting spark, there is fuel pressure in the line, but the only way the engine will fire is with a shot of starting fluid.
Any ideas?
I'm assuming there is solenoid somewhere preventing the injectors from working, but where is it and how do I test it? Can I bypass it?

 

Check the white/black wire that runs aft along the water rail. Easily damamged.This is the fuel injection trigger wire.

Check the bundle of ground wires at the rear of the water rail. They are the fuel injection grounds.

Check the connector at the coolant temp sensor. Poor connection = injectors won't work.

Check for voltage at the brown/slate wires at the injector ballast. This is the silver box on the right inner fender well, down low and well forward. If no voltage check the "main relay" on the firewall, identifiable by having the brown/slate wires.

Post back for more details, if needed

All of the above assumes a Ser III XJ6 with a 4.2 engine

Cheers
DD

 

Thanks Doug, I'll try to check those tomorrow morning!

 

I checked the wiring and grounds and found nothing amiss, so I tried once more and the car started! It's still skipping though despite the new plugs. At the moment the car has no exhaust attached to the cat-converter, but it sounds like I'm hearing a knock. I'm wondering if it's a stuck valve considering the car sat for 3 years?

 

It could be a bent valve due to standing, as you say. I had this happen on a 1980 XJ6 engine. Check compression in each cylinder.

 

I don't have a compression gauge, but with the spark plugs removed and the engine cranking there is a healthy "whoosh" of air that is comparable to the other cylinders.
If I pull the valve cover do I have to replace the bolts like the V12's?

 

No bolts. Two screws and umpteen dome nuts and copper washers that go onto studs.

Cheers
DD

 

I was going to test the injector on the dead cylinder to make sure it was working, so I pulled the plug and, not knowing if it made a difference as too which side of the prong was hot, I tested the connector with my test light. Both sides are lit up? Shouldn't one side be hot and the other grounded?

 

With the key "on" but engine "off", you'll have "+" voltage on both terminals. With the engine running you'll get a test light flicker as the ECU grounds the injector.

Cheers
DD

 

I tested it with the engine running and didn't notice any flicker, but I'll check again.

 

The best way to check the circuit is using a noid light:
http://www.amazon.com/OTC-7602-Port-.../dp/B0002SR4OA

Or...actually...just use a mechanic's stethoscope (or long screwdriver held to you ear) and listen for the rapid fire clicking of the suspect injector while the engine is running.

Cheers
DD