There is a torqx set screw on the shifter, having kids now that is something I think I would want to lock out. Just in case something happens.
You are not wrong for asking that at all. I tried scanning through the Haynes manual and the diagnostic manuals on my phone but I didn’t see the firing order there. I googled it and found a picture of a firing order. I assumed it was correct, It matched up to the current orientation. With how it is acting I would not doubt that at all. The wires look old, like they were the ones installed on the service that was done in 2013.
I don’t have any experience with the 4.0 six, but have a lot of experience with Jags not starting.
If it were me, the first thing I’d do is pull the plugs and inspect the burn pattern / condition. This will kinda point you in a direction, or at least another rabbit hole.
I’ve purchased several Jags, against my better judgement, that didn’t start. A code 22? OBD codes start with a letter such as ‘P’ then 4 digits. Anyway,
This is what I do first.
Check the compression if the compression is within spec and consistent,
Clean all of the grounds and tighten to spec
look for a parasitic draw on the system. (with a multi-meter)
check ignition spark, I have a HT lead with a light in the center so I can see if the spark is consistent. If you’ve got coil packs, then the HT lead / light is useless.
check the pressure at the fuel rail Check the condition of the fuel - How did it smell when you cracked the line?
Make sure it’s actually fuel and not water. On XJ’s just before that model, its quite common for the tanks to fill up with water if the filler cap seal isn’t replaced (more often than not… It’s not.).
check the timing mark on the crank, and make sure the distributor (if it has one) lines up accordingly
Ignition module - make sure it’s working. the XJ Series III the ignition module is usually the culprit, which is nothing more than a GM HEI module in a metal box. I usually swap these out with MSD equivalents. but this probably doesn’t apply
Tools that I find useful with these cars, are
Most important, a manual. The original service manual can be had for under $100.00 It’s worth every penny!!. It will save you so much time. books4cars.com, XKS.com, or OTPubs.com all have the OE manual on electronic media. OTPubs.com has it online too.
mult-meter,
NIBs (little LED’s that you can connect the injector (wired) connection to check if current is getting to the injectors
Does your 4.0 six have coil packs or a traditional coil?
if all of the above checks out, then I’d pop the cam cover off and make sure there isn’t any slack in the cam chain and that it is proper alignment with the crank shaft.
Not for the ‘40 these are OBD1
It has a single coil and the ‘distributor’ is merely a device to send the spark to the plugs, all the decision making regarding spark timing is done via the ECU
I am just using the manuals that I have gotten offline in pdf form. The diagnostic manual and the Haynes manual. I do have the plugs I have removed, but the car has not ran with the ones I have installed.
I should get an injector lead tester.
Everything you mentioned Mark I have checked. I drained the fuel and added fresh fuel to it, and replaced the filter.
Are there any connections between the battery and the engine compartment on the 12v+ side of the battery cable? Somewhere that could cause something funny?
Checking the coil and the 12v+ battery post on the firewall the voltage dips the same when I try to crank. It goes down to 10v, at the stud on the fire wall and the coil. It did that as well when I pulled the battery from my truck so I don’t think it’s the battery.
He is was having VERY similar problems that I am having. He threw a lot of parts at his car, and discussed a lot of in depth things but it ended up being the distributor rotor. He stated that his appeared to be in good shape, which so does mine. I just ordered one from the local parts store. I think someone mentioned it before on here, I can’t remember who though.
There have been instances with the battery in the boot, when the connection through the bulkhead has corroded leading to a loss of voltage, if the volts are pulling down to <>10v the computer is probably saying ‘no way buddie”
For the rotors a quick and dirty test is a dob of grease on the inside of the rotor.
That’s what I am worried about with the voltage. Where is the bulkhead connector located at? My truck battery cranks over my v8 every time, Evan after leaving the lights on for awhile when I’m working outside. I know the GM tbi isn’t as finicky as the jags with voltage.
Going through and cleaning all the connections on the + cable could make a big difference.
Ah I didn’t know about the grease trick. I will try That.
Jag man, thanks for the link! I’ve been reading through a few of his threads and they have been very helpful.
The rotor button was one of his problems, and his symptoms were very similar to mine aside from the tach reading. I ordered a new rotor, but I tried putting some diaelectric grease on the inside of mine today with no luck. It does almost read 1ohm across the button, that seems very high for what it is.
He also said the ignition amplifier fixed one of his problems. That’s an expensive guess, I don’t know if Autozone can test them?
I am worried I’ll never figure it out. After reading through all of your problems I feel like I may be in the same boat.
I know it’s frowned upon, and at this moment I don’t have the funds or the space but I can understand why people go to the SBC. I have a line on a “clean” totaled C4 vette with tpi and a 700r4, it’s something I am keeping in my back pocket. I would prefer to find a complete 4th gen f body with a LT1 to swap it. I have no desire to mess with LS engines right now, I’m old fashioned I guess. I would rather get the car running and put some Miles on it with the stock engine before I decide to do that.
Replaced the rotor and it fired right up. I was in shock. Let it run for awhile and everything seems ok. Took it for a spin and nothing stuck out except the brakes feel a bit spongey and the anti lock light is on.
Good job Tony. You now have a classy Jag your whole family can enjoy for a mere $500 and a little trouble shooting, good for you and welcome to the club.
How many times does it turn out to be the cap or rotor !!
First step in troubleshooting an XJ40 that won’t start or suddenly stops running is to replace the rotor/cap. Cleaning won’t do it, and I don’t care if it’s kinda “new” … REPLACE THE ROTOR/CAP. I’ve been told the caps have a real habit of developing an invisible carbon track that shorts it out. Beyond that I’m at a loss to explain it.
In the almost 30 years I’ve owned my car it wouldn’t start or stopped running only 3 times and all 3 times it was the cap/rotor. The reason I lump them together is because I always replace both of them at the same time. And YES I always carry a new cap/rotor in the trunk.
I can’t agree with Grooveman more and he has been very instrumental in helping me with my issues, BUT, and this is a big but, you have to have spark from the coil HT tower before anything downstream of the coil is relevant.
Tony verified in his first post he had spark.
This comment in post 26, so he clearly had spark from the coil and from that point it makes sense to replace the cap and rotor.
Grooveman, I will always carry a spare cap and rotor with this car. I was really doubtful when I got the new one, because my old was the same manufacturer. The old had zero traces of a short, it measured the same across the terminals. I guess I could of used the meggar from work to test the insulation.
I’ve trouble shooted quite a few non running cars, and as much as I start to over think it, I always try to stop and look for the obvious things.
Now I am dealing with a dead alternator. I’m searching for info on using a GM alt, but is it even possible on the later xj40s?
