Okay so a little back story here. I picked this car up when I was 19, it was my first purchase of a real car, my first being a Mercedes 190E 2.3 4-speed manual that I ran the tires off. When I first set eyes on the car I fell in love, instantly knowing I needed to have it. The man, seeing the sparkle in a young boys eyes, swindled me into paying more than I should have but I payed happily.

Turns out the car had belonged to a man with terminal cancer and hadn't lived much longer, to my surprise. The older couple that had been taking care of the older man had told me he spent hours, if not days, working on this car. It was his pride and joy. I should have known when he swore me, literally swore me, to take care of the car.

After a year of basic maintenance and care given to the car it inexplicably stopped running, draining the battery over night. I made the aweful mistake of parking it inside my dads hobby garage for the better part of 2 years while I went of to college to get my associates in Marketing. I had saved money for college and figured that it would be better off to work on the car when I was making more than 8 bucks an hour detailing cars at a local body shop.

So here I am at 22, detailing cars at a local body shop, while I work on my bachelors. I needed to figure out what I wanted to do with the car, work on it or live with the guilt of promising a dying man I would care for his prized possession then selling it (this guy obviously didn't have family, he was a recovered drunkard and abusive so says the couple that tended him when I asked why his children or wife never took the car.) I set out to rebuild the spark, fuel and vacuum to alleviate most of the problems. I've exhausted my funds, nearly 3500 has been spent so far and I fear that I won't be able to afford to keep the car if I don't figure this out. I've been tempted by my father to just convert to a 350 and 700R that he has in his shop (Dad's a hobbiest to the extreme, building show class bodies and working on concours aston-martins for Kevin-Kay so fabrication wouldn't be an issue for us nor would mechanical work, it's this darn electronics killing us.)

So here is what I have at the moment, I have fuel all the way to the fuel rail, it injects and seems like it wants to start but won't fire. It cranks over, receives spark but no fuel? It makes no sense to us and we've bought two different manuals for the XJ6 and none have anything on fuel injection, only carbs. My father put what I think to be carb cleaner in the injector to see if it would fire and it does, running on the fumes ( I know, really bad.) My only other guess would be some sort of loom or sensor that is bad? Is there anything of the sort that would cause this, maybe a crank sensor? Maybe we didn't clean the injectors thoroughly? Would I be better off just fabricating the parts needed for the late model 350/700r combo my dad has?

 

Good! But what's the fuel pressure at the rail? It needs to be 36 psi. Do you have a pressure gauge?

But, don't worry about fuel pressure until we clarify/verify what follows below:





Are you sure? How did you check for this? If the injectors are not injecting there are several possible faults....most of them very easy fixes!




Remove the plugs and give each cylinder a couple squirts of raw gasoline and try starting again. If the engine runs for a moment then you've confirmed that you have a fueling problem.

Of course, if you pull the plugs and they are already wet with fuel you can skip this experiment.

Cheers
DD

 

The Jag drive train is a dead end. They are unreliable, underpowered and very fuel ineffecient. A properly done mild 350 with 700R4 will get better gas mileage, be much faster and much more reliable than the Jag drivetrain. Inthe long run it will be far less expensive and easier to maintain. Since you and your dad appear technically capable you can consider putting TPI injection on that 350 and have an great running car with awsome driveability. It would also be an awsome father and son project because the end rusult would be awsome. I know... I have one with TPI and one with an LT1. The LT1 with its sequential fuel injection is amazing and nearly as smooth as the batch fire V12 it replaced. Since you have no way of knowing if the origional owner would care if you converted, dont make that a factor in your decision. It may have been something he wanted to do himself or not. Theres no way to know for sure. Converting to a 350 requires very little fabrication. There are kits for the engine and trans mounts. The proper length drive shaft can be ordered on line and the guages are easy to connect properly. You need a dakota digital converter box (80$) for the speedo. The tach can be converted for about 2$ in parts from radio shack. The rest of the guage senders will transfer from your jag engine to the chevy engine directly. The TPI computer can control an electic fan or you can do a traditional mechanical fan. More then likey your present radiator is shot and needs replacing anyway. The most difficult part is the driver side exhaust down pipe. It has to make a compound bend to go around the steering shaft. The 2nd most difficult is the custom hoses for the A/C. Every thing else is a bolt in or uses off the shelf parts. Put a set of kYB shocks on the Jag and you'll have a very reliable and capable performance car suitable for a young man to enjoy for many years. Your dad will love it too.

 

Although I disgree with your over-generalized assertions, I'm not against V8 conversions by any means. There are some perfectly valid reasons to go that route.

Seems to me, though, that you're suggesting the first and best choice in dealing with a Jaguar that won't start is to install a V8. There may well come a day when that V8 won't start. Then what? Install a different V8?

Anyone who is capable of performing a DIY V8 swap is certainly capable of returning a non-starting Jaguar engine to running status. Quite often it's a very simple fix....especially so considering the relative simplicity of the fuel injection and ignition systems on the 4.2 engines. It's very old school; most faults are quite basic.

I think it would be a shame to go through the effort and expense of a V8 swap when a getting the original engine back into running order might be as simple as repairing a faulty ground, replacing a dead coil, or some other very easy task.

Unless, of course, a V8 Jag is what a person really *wants* to do all along...in which case any excuse to move forward with the project is welcomed! I get that.

Cheers
DD

 

It will be more work to lump it (properly) than to diagnose what's wrong with the existing setup. Follow the advice given here, methodically, and figure out the problem.

 

Look at some of the recent but older posts on this and the XJS forums they are filled with engine problems. No start, I'm stuck, leaking head gasket etc. The fact is Jaguar was using 70's fuel injection technology until the late 80's. Surely it would be easy to fix a single issue and get it running but sooner rather than later another issue will crop up. Ususaly when it rains. Jaguar did not use weather tight connectors on their cars so all sorts of corrosions and connector issue come up constantly. Both my chevy conversions use off the shelf wiring harnesses with weatherpack connector and they always start even if I let them sit unused for weeks. I had a 86 series 3 with Jag mil, sometimes it started and sometimes it didnt. Thats very frustraing.

 

So we tested the fuel pressure at the rail and it's showing 36PSI than checked the injectors individually with a noid tester and had no response out of any injector while cranking. I will try separating and cleaning the connectors for the fuel injection tomorrow morning, any advise guys? Thanks again for all your help and your hopeful continued help.

 

No argument at all, especially about non-sealed connectors . And we all form opinions based on experience.

I've owned scores of GM cars and trucks, including Chevy V8s. Leaking intake gaskets, clogged EGR valves, multiple transmission failures, multiple alternator failures, dead throttle position sensors, leaky valve seals, oil leaks, leaking water pumps causing "Opti-spark" failure, coolant "wicking up" through the coolant sensor wiring....blah blah.

Don't get me wrong, most of them were darn good cars. But, "Chevy V8" is no guarantee of reliability in my book.

Also true that I've spent *plenty* of time over the last 16 years futzing around with Jaguars but I can honesty say that only once have I been on the back of a tow-truck...and in that case it was MY fault!

It's a little ironic that, on my XJS, the most expensive mechanical repair I had was having the GM TH400 transmission overhauled at 88k miles. The V12 engine itself gave no problems at all, mechanically. The over-baked wiring surely was a problem, though, among others!

Another bit of irony is that one of the most notorious sources of ignition failure on the older models is the GM-sourced ignition module

Most of the Jaguar quirks are well documented and easy to avoid and/or repair with far less effort than an engine swap. I can make a new V12 injector harness in about 4 hours, whistling while I work, for about $60 in materials. I can take a clogged Jaguar radiator to the radiator shop in just the same way I'd take a clogged Chevy radiator to the radiator shop. I can clean corroded ground connections on a Jaguar in just the same way I did on my brother's Chevy van a few weeks ago. You get the idea

I can think of a some great reasons for a V8 conversion. I can also think of some reasons why it would be needlessly "over repairing" a problem.

Cheers
DD

 

Check wiring at the coil. The ECU won't trigger injectors if (among other things) it doesn't get a pulse from the ignition system. Pay particular attention to the white/black wire at the coil "-" post that runs aft along the water rail.

At the end of the water rail is a bundle of ground wires under a bolt head. Make sure they are clean and tight. These are the main grounds for the fuel injection system.

On the right inner fenderwell, down low and well forward, is the injector ballast. Silver, about the size of a pack of cigarettes. Check/clean the connector/plug and make sure the terminals are clean. The connector has two brown/slate wires. Use your test light to see if these two wires have 12 volts with the key "on". If they don't, post back.

Check the connection and wiring at the coolant temp sensor. It's on the water rail, third item from the front. If the circuit is open the engine flat-out will not run. For testing you can jump the terminals inside the connector with a paper clip. If the engine now starts, you have a problem with the sensor.

Post back with results!

Cheers
DD

 

Doug you really seem to know what you're doing. If only I had your hands rummaging around my engine bay ~_~. Me and my dad can completely rebuild a early model 350 and body work is his specialty but all the electronics is mainly new and somewhat confusing to us, haha.

 

Thanks. If ya horse around with old Jags long enough you pick up a thing or two

Most of the electrical problems are pretty easy to fix. Sometimes we get a tuff one, though. Hopefully yours isn't one of them !

Cheers
DD

 

Well, I have a lump. I studied quite a bit before doing it. I was on he back end of a catastrophic engine failure !!!! Twas again leap for me.

Drop a Chevvy into it, it is easy. One of the great understatements of all time!!! I persisted and after alt of time and money, it runs just dandy. But, had I done the same for the busted DOHC, it might be running just dandy today.

I wrote a paper, "Lump thoughts". I've shared it with many and offer it here to anyone that contacts me PM at carl.hutchins1@sbcglobal.net

I just don't see a fueling issue with what is otherwise healthy engine as a reason to convert?

Replace a bad one, yes. Get much more power and OD, yes! Greater sources of repair parts, yes.

Looks to me like the solution is close at hand, with the expert tutelage of Doug!!

Very nice looking car. Well worth fixing!!

Carl

 

So I spent the better part of the day cleaning connectors. As you asked Doug we ran a test light to the Silver injector ballast and it showed nothing, not even a spark of light. We can't run a paper clip to the coolant sensor because some jackass decided to come into our backyard and steal my battery and spark plug wires. . . serious bummer. New parts coming in tomorrow from Napa so we'll run that test tomorrow. Thanks guys for the support and sorry for the late reply, also, thanks Carl we've put some decent amount of work into the car. Just wait till we start repainting : >

 

Forgot to mention, we tested the injector ballast on Monday, after work and all the cleaning/ adjusting the connectors for the ballast it was late so after work today I went to clean the rest of the connectors and test the Sensor but I found someone had stolen the battery and the SP wires. They left the Kenwood deck and MB Quart speakers though, hahah.

 

Hopefully, Lucas the Prince of Darkness followed along with the battery and spark plug wires to give the perpetrators a mighty swipe at the most inopportune time.

 

Okay so the parts needed from Napa auto parts arrived. After work I Plan on installing and checking the Coolant sensor. Any idea's about the Injector ballast? Thanks guys, keep the advise coming and you'll soon have this Jaguar back on the back roads! *Note* I am sure Lucas will give the perpetrator a nice surprise. I just find it odd that someone would steal a battery and spark plug wires, seriously, who does that?

 

You can get a little light that plugs into the end of an injector plug (instead of plugging it onto the injector). They have a technical name, and I have one in my toolbox from way back. If you want it, I'll try and look it out and send it, but you should be able to buy one in the US for not much $$.

If you plug one of these lights into an injector plug,and then crank the engine, you'll know the injection system is working because the light flickers on and off as the injectors fire. OK, it starves one cylinder of fuel for a bit, but is a useful diagnostic tool, because on these cars all the injectors fire together twice per engine revolution based on that ONE pulse from the coil wire. Without that pulse the whole shebang is a failure.

 

If there's no voltage to the injector ballast on the brown/slate wires then you may have a problem with the "main" relay on the firewall. Swap it with the fuel pump relay (which is right next to it and should look identical, if it's original) and see what happens

cheers
DD