As described in my post beginning late December 2017 (see Crane XR700 optical trigger & Crane XR700 12-slot shutter disk threads in this forum), my '76 preHE XJ-S suddenly died after backing out of the garage. I have now completed installation of new optical trigger and coil. While cranking with a remote starter switch (EFI disabled at the fuel pump relay), a strobe light indicates spark from the coil to the cap, and from the rotor to the sparkplug cables. This to me suggests the ignition system is OK. However, the engine still won’t start. Following a suggestion in the XR700 installation booklet, I disconnected “everything from the coil negative except the wire to the ignition module,” which on my car means disconnecting the tach wire. After that, the engine coughs/sputters very briefly, then nothing. Fuel smell suggests the EFI is working.
I’m now thinking battery, or perhaps starter/alternator issues.
I have no idea all the steps you have taken to diagnose, but if it were me I would just start diagnosing fresh off a clean flowchart. It almost seems like you are guessing - I say that because of the trifecta of battery, starter, alternator that you now suspect.
Begin with checking the battery first. Does it have full charge?, any damage?, is it old and rapidly loses cranking power? are the cables firmly connected at both ends and no corrosion or other cable damage?
If battery is good, move on to #2.
If the battery and cables check out good, what makes you suspect a bad starter? with a fully charged battery does it crank slowly or have another functional problem? Does the use the starter relay engage the starter and turn the engine over? if yes, then go to #4.
I’ve never seen an alternator keep an engine from starting up. I have seen bad alternators not keep a battery from being properly charged. This is a separate issue to address after getting the engine started.
This could almost be #1 - does it have a fresh properly connected fuel filter? If yes, then have you tested the fuel system for proper pressure, don’t forget the fuel pressure regulator. Is the fuel old? Is there fuel in the tank?
Of course I would move on to test and inspect the ignition and fuel injection. Do not presume anything, be methodical using the factory service manual. Fuel smell does not mean the fuel injection is working properly.
I dislike reengineering the ignition system on an engine that has mysteriously sputtered to a stop - this introduces another variable into the diagnostic puzzle. With the aftermarket ignition the factory service manual can not help you diagnose. I like and use aftermarket ignition systems - but probably due to the aftermarket’s smaller production numbers, I have generally had greater reliability with factory OEM parts.
If all the above systems check out, then there is some form of mechanical failure.
Well, I thought I had been methodical, but apparently not methodical enough so am crying out for new avenues. You might want to take a look at my earlier threads to see what I’ve done already.
Let me try to respond to each of your points.
1 & 2 (Battery, starter):
Throughout the episode I’ve had it on a charger. My charger has a booster setting which I flip it over to while cranking/trying to start. That said, I just today looked back in my records and see that the battery has been in service for 7 years. I’ll get a new one Monday, just on general principles. Cables look good, and I get a good 12.6 or more at the coil with ignition on. I don’t remember what it was while cranking, but I did check it and was not concerned. I’ll check it again. And yes, it cranks properly.
Alternator.
I admit I’m grasping for straws…
I haven’t checked the fuel filter. However, if it were clogged, why would I be getting fuel smells? There is fuel in the tank. I’m going to check the rail pressure while cranking today. I will also replace the filter though, since it’s been in service for quite a while.
Regarding reengineering, I happen to agree with you. E.g., I’m the one here always advising against electric fans, aftermarket radiators, etc. However, what is one to do when the OE part is NLA? It has been many years since the preHE ignition module was an available part. When mine failed over 10 years ago I chose the Crane XR700 because several prominent members of the Jag-Lovers mail list had done so with good results.
Ed, I’ll guarantee you will get it running, and it will probably be something like a broken wire. I grew up as the son of a master mechanic. I was in awe when my dad would work on a car that he had never before laid eyes on - yet he was still able to figure out what needed to be fixed, even unusual electronics. He had me overhaul a Dodge 318 when I was 12 years old, he did all the heavy lifting, I did the dingle ball hone, lapping of the valves and a fair amount of the assembly. Whenever we went on family vacations he always packed spare parts and a tool chest - no way would we be stranded even if the car broke down in a national park. I never expected I would be as good as him - but many years later he came by my home shop and remarked that I was working on things he never would have touched.
Some of my hard won lessons were:
Always start with the basics, it all revolves around suck, squish, bang, boom - and the proper timing of valves and ignition with proper fuel delivery.
Always inspect the last item that was repaired, never assume something couldn’t go bad twice in a row.
I understand about unobtainable parts, sometimes you just have to deal with the added variable of not knowing if it is working correctly. Is there anyone who might loan you the stock part so that you could eliminate that variable, get it running, then do the ignition conversion?
If you were in my neighborhood I would come over and help you knock it out, I always enjoy the challenge of bringing a dead car back to life.
Right on, Thomas! Thanks for your confidence. What I lack in diagnostic skills I try to make up in persistence
Just did a fuel rail pressure test… right on at 32 psi.
I ordered a new ignition module from FAST (www.fuelairspark.com). Since I have already replaced the optical trigger module and coil, this will be a complete renewal.
BTW, the Crane ignition systems is really a very old aftermarket ignition, made to replace points. It was a step back in technology, since the OE system used a magnetic pickup and was probably more robust than the LED/photocell (or whatever). However, the module was notorious for failure, probably due to being placed in the Valley of Death. FAST is the current owner of the Crane stuff, and I understand before Crane Cams bought them out it was an Allison.
One of the hardest things for the hobbyist mechanic to do is to be methodical - when I have encountered people in your situation, what I find that they have jumped around in their diagnostics. What happens is that it then becomes a long drawn out process. Most master techs have a mental checklist that they do the same steps in the same order on every car with this kind of problem, and would allow for perhaps two hours of diagnostic time. Usually they find the problem before they get to the bottom of their checklist, and then they tell the parts department what parts to order. The car comes off the lift while parts are being shipped, and another car goes in the bay.
You mention you are getting a spark, but is it happening at the right time?
My thoughts would be to check the timing of the (new) optical ignition pickup. Maybe its out by 180° or something?
Rgds
Mark
PS I had one engine that did everything right, but wouldn’t fire. When discussing with an old mechanic he asked me if I’d checked the compression? He said they’d once had an engine they couldn’t start and found that the compression was too low. I checked the compression, and he was right. Replaced the rings, compression came up, and engine ran fine. Weird, I know.
Not weird, I had an engine supplied by a parts place for a car I had in which had blown the original one. My guys played around with it for a couple of hours before going home.
I dropped some oil down the bores turned the key and it fired straight up.
I sent the engine back for a refund/replacement.
Another one, again couldn’t get it started, the guys went home and I rotated the spark plug leads 180 deg. Guys came back to work the following day to a right dressing down as I had already asked them to check for that condition. GRRRRR
I believe it’s OK. I have a spare distributer cap with a hole cut out at the1A position. I used my timing light to illuminate it while cranking so I could see the rotor pointing at 1A. See photo in my thread on 12-slot shutter disk.
I’m sure it’s not a compression issue. The episode began when enging died after backing out of the garage. Heads were rebuilt 3 years ago.
I’ve ordered a new ignition module, thinking it might not be putting out enough current. The spark I observed wasn’t the “bright blue” I’ve read it should be… seemed to be kind of wimpy. But then, I don’t do this kind of thing every day so don’t really know.
Also will replace the battery. It’s 7 years old although it’s cranking pretty well.
Put a new battery in this morning and, lo and behold, it started! Also took it for a test drive and it ran great.
Something’s still not right, though, as the tach doesn’t work. At some point during my various tests, based on the Crane No Start diagnostics, I disconnected it from the coil - terminal. At that time, the only effect was a slight chug on the first crank, like it fired once only. I left it disconnected for all other testing & replacing components. After it replacing the battery and starting successfully it a few times, I reconnect the tach and it wouldn’t start. I disconnected it for the time being so it will run.
Needless to say, I a little chagrined by all this. Could it have been the battery all along? Looking over my notes, I see that coil + fluctuated between 7-8v which I judged to be a little low but OK. In retrospect, that was probably a bad call. OTOH, along the way I found things that definitely needed fixing and might have caused or exacerbated the problem. E.g., when I replaced the coil I found the old one to be leaking oil, and I found and fixed a few dodgy connections. I do have doubts as to whether the optical trigger actually needed replacement. The new ignition module arrived today, but it will remain unopened for the time being.
So, before I close off this (and the earlier related threads), does anyone have a suggestion on how to pursue the tach problem?
If connecting the tach wire to the coil causes the engine to not run then there are a couple of possible problems: Either the tachometer itself is defective or the wire leading to it is shorted. My money is on the shorted wire because although tachs can certainly fail, it is very unlikely for it to fail shorted. Disconnect the wire from the tach itself and connect the other end of the wire back onto the coil post. If the engine runs the tach is likely to be bad. If the engine doesn’t run then the wire is shorted somewhere.
The wire from the tach (WSU) goes thru the 8-pin block connector near the center of the firewall. From that connecter it goes to the uppermost pin at the input end (aft) of the ballast resistor pack, which is a straight pass-thru to the corresponding pin of at the output (forward) end of the pack. The latter pin goes to the coil -. I’ve confirmed continuity of that path from the plug pin to the coil wire. Also, there is no ground connection of that path. Checking the WSU wire further would require pulling the instrument cluster, unfortunately. I have done that many times, but I hate doing it because the flex circuit is so fragile.
BTW, the other wire at coil - goes to the Crane ignition module.
The Crane instructions say that some Smith electronic tachs (which I believe is used on my car) require a diode in the connection between the coil - and the tach instead of just a wire. I believe there was such a diode in the Crane kit I got many years ago, but I must have determined I didn’t need it. It would be strange if it would become necessary after all these years. But, rather than pulling the cluster I’m inclined to try it. I suppose any diode would do, right?
BTW I have a spare tach but don’t know if it works.
Do you think I could test the tach from the engine compartment using a signal generator? I inherited one from my father-in-law years ago and guess I could figure out how to use it.
Also, is there any possibility the problem might be in the ignition module? I got a new one just in case I needed it, and it might be easier to install it than pulling the instrument cluster.
If the signal generator could put out a 12V square wave it should activate
the tach just fine. But my point is that the tach should have absolutely no
effect on whether the engine runs or not. The diode in the line was to make
the tach work, not let the engine run. If the ignition module makes the
engine run then connecting a functioning tach to it should have no effect at
all. Did you test the tach wire to see if it was shorted to the chassis or
to 12V? Measure the resistance between the tach wire (disconnected from the
coil) and ground and see what you read.
Mike Eck
New Jersey, USA www.jaguarclock.com
'51 XK120 OTS, '62 3.8 MK2 MOD, '72 SIII E-Type 2+2
Mike,
_[quote=“Mike_Eck, post:14, topic:360647”]
But my point is that the tach should have absolutely no
effect on whether the engine runs or not. The diode in the line was to make
the tach work, not let the engine run. If the ignition module makes the
engine run then connecting a functioning tach to it should have no effect at
all.
[/quote]
Your assessment of what ought to be agrees with mine, but what happens contradicts.
Yes, I did. When my DVM is set to show connectivity, there is none. Set to Resistance it shows infinite. I’ll double check tomorrow. Will also put the connection directly to the coil -, as you suggested before, and see if it starts. I didn’t do that because I assumed that since the path through the ballast resistor pack was OK it would produce the same result.
What do you say about the ignition module possibly being at fault? It wouldn’t be difficult to patch in the new one just to see.
Mike, you’re right. There’s something wrong with the internal connection in the resistor pack. Regardless of whether the new ignition module or old one is used, it will not start if the tack is connected in the OE configuration through the pack. If I bypass the pack it starts and the tach works just fine.
So, I’ve got some tidying up to do but otherwise this project is finished… I hope
Thanks to everyone for their suggestions and encouragement.
