Not sure if the fault is in te original jaguar or in thr lumped part.
i’ve not been driving it for months. for a time, i started it and let it run in the garage. Teh last ime, it did not start, but did crank heartily. For a time, the gas guage shwed quite lw on each tank. We added about 5 gallons to the left tank, charged the battery. Great crank. no run. But, now the gas guage is not responsive. and, the tach needle does not repond. Igntion or fuel issue?
I will study the S57 later today. and, after the storm goes by, check out what might tbe the fuse involved.
5 gallons should be plenty to prime the pump. That still leaves you with fuel and spark.
Try fuel first, correct tank selected:
valve stuck? - do you have return into the tank if you look way down the filler neck?
or pump - noise at least?
or injector stuck.
The fuel sender can be checked, when you remove the rear light and short the wire to the tank, ignition on, the gauge should peg. if it doesn’t the switch is highly suspect.
if it pegs the float has sunk or the gauge is stuck from sitting. I don’t think anything in the fuel system is fused!
as to the needle… if it is different to how it used to be it’s an ignition issue but that’s so easy to check.
[quote=“Cadjag, post:1, topic:429423, full:true”]
Great crank. no run. But, now the gas guage is not responsive. and, the tach needle does not repond. Igntion or fuel issue?
I would suspect ignition, Carl - have you checked, with a spare spark plug, if you have sparking?
You can check if you have power on coil ‘+’; the ign key may fail to power the ‘original’ white circuit. It depends somewhat on how much of the original wiring was kept - no power on the white circuit will give the symptoms described. The batt warning lamp should originally come on with ign ‘on’ if the key gives power.
The involvement of the inertia switch, being tripped, may warrant investigation. A fueling issue would relate to the engine fitted and rewiring to match - not covered in my manuals of course…
Good evening Carl - and still a very happy and healthy year for you and your cars!
As you describe it I’d almost be sure it is a - simple! - ignition problem. - A petrolhead like you (no offence!) would have smelled if there had been a fuel leak drying out the car, - Does the LS engine have any ignition relays or anything of the kind that may go wrong?
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Yesterday, I had another go at it. Fuel selection switch now works. Gas guage reflects left tank about half full. Right tanmk, very low. Makes sense.
Still, Carl; do you have sparks when cranking? Also, the gauge reading is independent of the changeover valve position. You may draw petrol from an empty tank - it’s not unique for the changover valve to fail…
A somewhat cumbersome way; dram each cylinder with a teaspoon of petrol - then crank. If the engine catches and runs briefly; it confirms that the ignition is working.
The ignition system is a self contained sub system - with power on coil ‘+’ (jumpwired from batt ‘+’ to bypass ign switch) a functioning ign system will work irrespective of other faults…
More intriguing; in wet weather, dampness of high tension leads and/or dist lid will disable ignition…
Or just try starting fluid and if it fires it is a fuel issue. All the basics Carl knows very well.
In the original the ECU gets its rpm information from the distributor and fires all six injectors with every third spark. If it gets fuel (which you can tell easily from the return into the tank unless the system was changed) I‘d go to the tailpipe and see if there is a fuel smell. If not either it’s not firing the injectors or they are all stuck.
I have satisfied myseltf tht the fault is not behind the dash. The gas guage responds to the tank selection switch correctly. it had not done so!. i attribute that to exercising a switch that has been dormant for quite some time.
My focus will be now, under the bonnet. depart from jaguar stuff to the Cadillac stuff.
Aye check for spark with a spare plug. i have one with a ground lead for that purpose. plus check the inertia switch. long shot, but easy.
I do have a relay under the bonnett for the fuel pump and I think I installed a blad fuse.
Priming the V8 is not feasible vai a spar plug hole ss it is in the OHc 6. I may have some ether to squirt in to the intake Not sure if i can do that drectly.
I can crank with a specia wire while under the bnnnett. Installed when i had starter issues.
However, it will be a few days. when our storms give us a break and when i do my med visit this thursday.
So if the switch that changes tanks didn’t work correctly at first it would be highly suspect as the contacts for the gauge are of course not the same contacts as those for the three solenoids.
Without power to the solenoids it should run off the left tank though. So keep going in the engine bay. And just check that there is any fuel pressure on the lines, then it should at least cough if the rest was okay.
Son was by yesterday. We had another bout on the jaguar. under the bonnett. all fuses that might be involved checked. Blade fuses as a part of the transplant.
could not find my 'spare" spark test plug. but, used a timng strobe to detect spark at any cylinder. NO flash. Clear, no spark! supports thery as the tach needel lies idle when cranked.
Checked connections at coil/module. tight.
Bad coil module. Not hard t replace.
Optiite distributor That is a PITA to swap out. Knwoning that, when I instaled the GM engone twenty years ago, i installed a genuine new Optilite, That was sans bonnett and radiator. Now that was nt easy, now, oh boy!
I’m not familiar with the ‘Optilite’ distributor, Carl. But if it uses the same external ign amp (4-pin) module as the Jaguar HE ignition - there should be 2 wires from the dist to the external ign amp…
These modules are natural suspects - and it is generally easier to replace a module than to test for module failure. Any fault in the dist (pick-up) can be addressed with the dist in place - access depending. of course.
It may be a coil issue - have you checked coil primary resistance? Also, since external amplifiers are usually powered from coil ‘+’, as is the ignition itself, a jump wire from coil ‘+’ to battery ‘+’ is another quick test to bypass other electrical faults…
That is next on the agnda. The GM ccoil & module is packaged in such a way so as to make it near imssible to jump +battery to = coil!
There is a way to bench test. Complex.
i have the Gm manual iut for research. it is a big tome!
today is out. and the next. Doctor visit. and a day after to recover.