Hi all,

First of all, let me apologize for spawning another "no start" thread. I see several folks that must have replied to hundreds of these things. However, I didn't want to hijack someone else's thread and cannot find one that is specific to where I'm at.

I'm sorry.

For those of you that don't read all of the new member intros, I just picked up an '85 XJS HE. It ran when I bought it, but very poorly - I trailered it home. Played with it a bit, found it was very hard to start and would die often. Drivable, but barely, and died during the drive - had to wait for it to cool down to restart.

It had been sitting for quite some time and I have some experience with older cars like this. I have an '80 Porsche 928 which has pretty much the same fuel injection setup so I know that first step is to replace all fuel hoses to avoid car-b-que. Along with it I figured to replace distributor cap, rotor, plug wires, cracked vacuum hoses, brakes, etc. Went to a single low impedance coil.

The fuel injection harness was cooked. Not a surprise so I built a new one, TXL wire and new connectors. Sent the injectors out to be cleaned and flow tested.

Pulled the distributor and got the mechanical advance working again. It was glued together with old varnish that used to be oil and / or grease sauteed in engine vapors.

I think that's most of the engine related stuff. After putting it all back together, here is where I'm at. No start - not a shock with all the stuff I messed with.

Drained all the old gas, cleaned the sump tank and filter out. Icky. Flushed the fuel lines with clean gas, then replaced all the rubber hoses with fresh injection hose.

- I have spark. Strong, blue spark at the plugs.
- What I don't think I have is fuel.
-- The pump does NOT come on for the first two seconds after the key is turned. It used to, so I broke that somehow.
-- Don't hear any injector noise.
-- I can short the pump out and get fuel at the rail. I've tested the pressure and it is nearly 40 psi.

** It WILL catch when I spray starting fluid in the intakes. I tried to follow the rules for marking position of the distributor and putting plug wires where they're supposed to go so I was concerned that I had self-created timing issue. I can't rule that out yet, but given that it seems to want to start when given fuel directly I think the ignition is OK, at least enough to get me going.

I've read as much as I can find and I seem to recall seeing a troubleshooting method for no start that told what to do when this happened.

I'm thinking I remember it is either the temp sensor (water) or ECU. I tested the resistance of the sensor by the LH thermostat and get ... well, I don't recall off the top of my head but it was in line with one of the sources I'd referenced - I think the Kirby book.

I do recall seeing that I can jump it with a resistor, which seems like a pretty good thing to have around so I'll pick one up when I get a chance. I don't think that is it though...

I've cleaned up grounds but I'm sure there are some I'm missing.

One thing that might be a big red flag is that the little tiny white wire coming off the ignition amp cracked right next to the connector. I soldered it back up but had to pull back the wire loom / insulation and learned that inside that the wire is shielded and that there's a black wire running next to it. I believe that the black wire and the shield are connected.

I know that wire signals back to the ECU. What I don't know is how to check to make sure I "fixed" it right.

I've probably provided enough information to make pretty much anyone's eyes glaze over.

Looking forward to getting this thing running so I can see what it is like to drive one.

 

You've covered the bases very well.

One quick thing before I turn in for the night:

Do you have 12v positive on the pink/black wires from the fuel injection "main" relay? The pink/black wires feed 12v to the injectors and powers-up the ECU.

More later

Cheers
DD

 

Also, but not only.

That mystery wire you have "repaired" is the key to injector pulse. It transmits a signal to the ECU that there is ignition activity (spark) so all is sweet to activate the injection firing system. Sooooo, no pulse sensed, NO injection fire up, NO go.

What you repaired is possibly just the "tip of the iceberg" scenario. Most I have had to sort have that wire toasted all the way back to the exit point of the engine bay near the RH lock plate (our brake booster).

To test your repair. Unplug the ECU, located pin #18 in the plug. That is the end of that thin shielded wire. Test it for continuity. If it test OK, then it is deemed OK, most do not. Also pay attention that the continuity is NOT to earth for that inner thin wire, that is another common issue with it.

A simple paper clip will suffice to trick the CTS, no need to buy a resistor.

 

Further to Grant's and Doug's points, and about the little white wire with the mesh shielding. The black wire is an earth and should be soldered to the mesh shielding and NOT earthed directly and be carefully insulated afterwards. The inner white wire (that Grant explained the importance of) must NOT be accidentally connected to the mesh shielding or the black earth wire, or anything else. It just occured to me that you might have inadvertently created a connection when you soldered the white wire.

Welcome to the elite!
Greg

 

Chris,

Did you by chance change out any relays in an attempt to be pro-active?? The Main and Fuel Pump relays back by the battery are NON-STANDARD relays. They look like normal 'change-over' relays, but are in fact just 'double contact' relays. Meaning that instead of changing power from one terminal to another when activated, they POWER UP those two terminals at the same time when activated. Putting the wrong relay in either base will leave you with a no start.

Just a thought.......

 

Thank you very much for the fast replies! What a great asset the internet can be...

Here's what I've found, based on your much appreciated suggestions. Please note any incorrect assumptions I've made so I don't start getting incorrect knowledge stuck in my brain.

Had to untangle the leads on my multimeter to pull this off... and add another clip on lead to reach from front to back. I do have continuity on the thin, inner wire. I moved it around a bit (not too much - not wanting to tempt fate) and the connection seems to be good between the amplifier and pin 18 on the connector.

I've shorted the CTS, just to eliminate it from the equation.

Good - when I removed the insulation from the wire it was unclear if they should be joined or not. I decided, "yes" when I noticed a copper clamp in there. Also remember seeing somewhere that the ground needs to be at the ECU, not elsewhere. Shield and black wire are soldered together and insulated.

A good thing to check... so I did. White center wire and shield do not have continuity. If I test continuity to ground in the engine compartment I get a connection that is nearly good contact but not quite. This would be consistent with a ground that is good at the ECU but not the engine, I think? I do see that the shields for several wires are tied together at the ECU and would imagine it goes to ground somewhere?

If that just means, "you own a Jaguar", then thank you very much! Happy to be here. If you mean, "you know what you're doing" then I'm afraid you may have made a mistake.

I saved the first response for last, though, because this seems like the direction I need to go...

I'd better make sure I'm looking in the right place, here. In the trunk (I'm sorry, "boot" - must get used to British car lingo) near the ECU I have two relays. One is red, which I believe is the main power relay back here. The other is a rather tarnished silver metal relay which I believe is the fuel pump relay.

Most of the wires feeding in to both relays are brown, which I understand is the usual color for a hot (positive) lead on these cars. The silver relay has a bit of "custom" wiring from the PO which is a switch from the orange wire to ground. That switch will cause the fuel pump to turn on and run continuously.

I'll reference that relay as the "fuel pump relay". There is schematic on the side but it is tarnished enough that I'm having a heck of a time deciphering it. I've got the Haynes book, and the wiring diagram includes cold start injectors (which I don't have) so I know it isn't spot on. I do have the "real" shop manual on order (at a pretty penny but faster than waiting for the CD from Britain) and am anxiously awaiting its arrival any day now.

Here's what I think is going on...

It has an input (pin 30) direct from the battery. The contacts that activate it appear to be 85 & 86. 85 powers up from the red "main" relay when the key is turned on. 86 should be the ground and it comes from the ECU. When I ground that wire the fuel pump starts.

I did think that I might have a bad relay and was out running errands so I stopped by my local auto parts place. They didn't have the exact Bosch relay in stock but the parts guy found one that appears to have the same schmatic on the side. This leads me to...

I didn't swap them out proactively, but perhaps that's something I should consider... once I know I'd be putting the correct relays in.

My original relay does not have any power on either pin 87 (center pin and the pin opposite battery power) unless I ground the orange wire.

My replacement has power on one pin 87 in the center but not the other, unless I ground the orange wire.

I wonder if I have a bad original relay and then tried to replace it with the wrong one?

The other thought is that the ECU is supposed to supply a ground using the orange wire but isn't because there is some other condition that is telling it not to run the fuel pump. Seems odd that it will command the starter motor to fire but not the fuel pump? That doesn't seem right, but it does appear that the ECU has to believe that the car is in P or N, various sensors are in certain states, etc, before a start is allowed.

So, what I will do... I've got to head out again so I'll swing by a store that does have the right relay in stock. I have located it, just wasn't nearby earlier.

I'm starting to get more worried about my ECU as well, but may be premature at this point. Probably a good idea to start looking around for one, though. Suspect that having a spare would be a bright idea.

If this helps narrow things down and points in a different direction please let me know what to look at next.

Thanks, gentlemen, for your excellent advice. Let the saga continue...

 

If both terminals 87 get power when the Orange wire is grounded, I'd say the original relay is OK, but get rid of the other one.

If you ground the Orange wire, will it start and run?? If it does, then you'll have to pin down either why the ECU isn't grounding the pump relay, or why it CAN'T ground the relay.

Good luck!

 

Hey, Steve, just noticed you're in Indianapolis. I lived there for 7 years or so back in the late 80s, early 90s. Great town, just couldn't take the winters.

Yes, duh, you're absolutely right. When I ground the orange wire the relay activates and then both terminal 87s get power. The fuel pump fires up and I can hear the fuel returning to the tank as it makes the roundtrip through the lines and rail. I see no sign of injector life... should probably pick up a noid light.

No start, though. That wire was tapped by the PO and a switch installed to keep the fuel pump running all the time so that's easy for me to test. I did yank that out to make sure the tap hadn't broken the wire but I'll probably put it back.

Need to figure out why the ECU is not triggering the fuel pump for the two second run it is supposed to do when the key is switched on. I think that once I can answer that question that my problem will be solved.

Somewhere I know I saw a list of things that will keep the ECU from allowing fuel. I'll see if I can track that down.

 

I'll come back later but, first, you need a decent wiring diagram.

Click here:

http://www.captainjaguarscathouse.co...ec%20Guide.pdf

You'll get the S57 Diagrams. It opens with Ser III XJ6 stuff but continue scrolling down and you'll see the "XJS thru 1987" section, then scroll to section 24.1


Also, go to the "How To" quick link at the top of this section and then to "Downloads Assorted tech files". Then open the S58 Engine Performance Guide. It has some good info that you might like on general principle

Cheers
DD

 

As I recall it simply comes down to an internal ECU fault.....bad solder joint or internal switch or something like that. It won't be anything external that I know of, other than lack of power and ground.

It isn't a very smart circuit. When the ECU sees "key on" voltage it grounds the fuel pump relay for a couple seconds....right up to the point where it doesn't do any longer

It's a fairly common issue.

Cheers
DD

 

PLUS.....

A couple of them have built-in diodes so replacing them with a generic will really bollix up a diagnosis!

The relays with the diodes generally have a diagonal paint stripe across the top and, of course, the miniature diagram will show the diode

Cheers
DD

 

The ECU doesn't control starter operation.

However.....

The starter relay will not operate unless the "feedback inhibit relay" is closed.....and the feedback inhibit relay won't close unless the trans is in "P" or "N". This is to force open loop operation in "P" and "N".

I have no idea why Jaguar put the starter relay downstream of the feedback inhibit relay

Cheers
DD

 

Doug, I can't tell you how happy I am to see these electrical diagrams. I'd started to download them once and decided that there was something wrong with the connection. It was actually because they're so big - 'cause they're wonderfully detailed. Those will help a lot.

I'd seen some of the other documents but I'll make sure to take a closer look at the S58 guide.

I'm thinking I have a bad ECU. Everything I have seen is pointing that direction. I bought one today and it should be here later in the week, maybe first part of next week. The cat will have to sit for a while.

I'll finish up the brakes - new master cylinder, rotors, calipers, hoses, fluid, also did the Mitsubishi fluid reservoir since the switch on the old one was bad. Might leave the rear ones until I can drop the suspension and replace all the rubber. Not sure about shocks and springs... it doesn't sit too low so we'll see.

Thanks again for all the advice. I'm sure I'll have more questions to come later.

 

From all you said it looks like you're well on your way towards a well-sorted XJS.

And a well-sorted XJS is a fabulous car to drive with a unique feel about it.

Worth the effort, IMHO. I think you'll be pleased when you're all done.

Cheers
DD

 

The kitty purrs!

For those following along at home, there were two significant problems.

- The ECU was bad and that was why I was not getting the "two second fuel pump run when ignition turned on". I got the "new" one in last night. Plugged it in even though it was after dark because I just *had* to see and... It acted exactly the way it did when I tried starting fluid. Sorta fired but didn't quite want to start. Sadness.

- The distributor rotor was off by one tooth. Today I started over with the basic "no start" items. I had spark, check. Fuel was coming to cylinders now, check. Air didn't seem like a problem. Engine really wanted to fire but just wouldn't quite catch. Put #1 cylinder at TDC using the timing mark and the techniques described in Palm's Book. Rotor was almost, but not quite, pointing at #1 cylinder.

Pulled it, moved rotor and put it back in. I've become much more familiar with the XJS setup and have been reviewing everything I could find on what it takes to get these things running so the description in The Book on how to set the distributor timing made sense now.

There's a paragraph attributed to Michael Neal that describes how to position the distributor. I used that and I bet it is dead on.

Once I'd done those two things, when I turned the key the engine started almost before I'd gotten the key all the way to "start". Immediate start, kicked in to a nice fast idle.

There are plenty of things for me to sort out. I completely disconnected all the vacuum stuff, shorted out most of the sensors, plugged the vacuum ports in the engine. Need to make sure the vacuum advance is working - didn't have it hooked up so the engine got plenty hot plenty quick.

It didn't take long to start getting smoke as oil burned off the exhaust pipes. The transmission leaks BADLY and there's fluid all over the cats that are right there. There's oil that would have run down on the downpipes.

I'll check the timing and make sure the vacuum advance is working correctly. I think that the advance mechanism will work - I pulled the advance unit apart and put in a new diaphragm and it seems to function.

Anything come to mind that I should consider a "must check" or should it be safe to take it out for a (gentle) spin?

 

WELL done, great stuff. As for the vac advance, I suggest just hook up one vac tube directly from the small take off underneath the A bank throttle body directly to the vac unit, and forget about and remove all the rest of the nest of vac lines, EXCEPT anything connected to the cruise control bellows (assuming you want to keep that).

The oil leaks will be a quest in themselves! (Cam covers, half moon seals, tappet block), the Great Palm's book being very good on how to stop them. The oil pressure sender and warning light sender may well be leaking and are worth changing anyway. Best to remove the throttle capstan to do these, and be sure to support the aluminium casting they fit to against the spanner torque when you undo them, or the casting can snap off!

Congratulations again.
Greg

 

I have an 89 XJS, with 38K miles. I've had the car for a number of years, in storage. It would always start. I went to Afghanistan for two years, came back......and no start.

I had the injectors tested and cleaned. I had good spark, but no fuel at the injectors. I then changed the fuel pump relay and viola, it started. I let it run for a minute and shut it down. I came back to the car a few weeks later and the same problem arose.....no start.

I have continuity between pin 24 and pin 18. I checked continuity with pin 24, on the ECU, to ground.....it was 4.16 mOhms. I checked both relays in the trunk, they both are new and they both work properly. They switch power from terminal 30 to terminal 87.

I have 12vdc on each of the two pins on the one injector connector that I checked. I unplugged the Marelli power modules, on the radiator, and checked for voltage:
Right module:
Pin 1: 12v
Pin 2: .3v
Pin 3: 2.6v
Pin 4: 12v
Pin 5: Blank
Pin 6: 2.7v

Left module:
Pin 1: same as above
Pin 2: same
Pin 3: same
Pin 4: .02v ***
Pin 5: Blank
Pin 6: same

I didn't check voltage at the resistor pack. I did check resistance, resistance was 5.4 ohms between pins one and four and pins two and three. (there was one pin that was not sticking out all the way. I was able to pull it back out and fix it. still no start)

Tomorrow I will check pin 24 back into the engine compartment. Will let you know.


DaveS

 

Also... check your grounds. The ECU is really touchy about that. I'm not sure why there is such an issue with that on this car but there is.

 

I imagine that the 4.16 m Ohms reading to ground is not good. That this is an indicator that there is a short?


DaveS

 

I pulled the plug on the resistor pack. Ignition switch in the run position. I do not have any voltage on the pink wires. I have 9 volts on two the orange wires and 12 volts on two of the other remaining wires.

Do I have an ignition amplifier on this car? Should I be verifying that the small thin white wire is transmitting a signal, that it has continuity to pin 24 on the plug on the ECU located at the A pillar? (I do have continuity from pin 24 to pin 18 in the boot, at the injection module.

I've cleaned up the ground points on the car, all looked good nothing unusual.

Suggestions?

DaveS