Help! We have a 1988 Jaguar XJS V12 that was towed in for a no start and we've tried everything and can't get it to run. Owner was talking to a friend in his driveway with the car idling and it shut off and won't start since. We replaced the plugs incase it was flooded (what a bear that was). Car has spark, fuel pump runs, has no injector pulse unless you pump the gas pedal. If you pump the pedal as fast as you can you can get it to try and take. Car does not have crank sensors, all the information we can find is so mix matched, some info says car should have these sensors and wire, some wiring diagrams say (ex: 1990-91) but this car doesn't have those parts or wires. Tried tech lines, sent computer away to have drivers tested for fuel injectors, at a complete loss and not sure where to go. Coolant temp sensor and air temp sensor read properly. If you disconnect the throttle switch the attempting to start while pumping the pedal stops and the car does nothing. Throttle switch is very expensive so I don't want to just throw one at it and hope it sticks.


HELPPPPPP!!!!!!!!!!!

 

Do you have Lucas ignition? We need to know this before we can make suggestions.
If the plugs are definitely sparking (fat blue spark) then it is fuel. If you squirt starting fluid into the butterflies, will it run?

 

Yes it has spark, with starting fluid it tries. And yes, the black box on the back driverside intake says Lucas AB 14 Electronic Ignition Amplifier

 

Have you read the "no start" writeup linked in the first post here? https://www.jaguarforums.com/forum/x...he-v12-178286/

If the fuel pump runs and it you are having spark, my first thought is the wiring coming out of the ignition amp. (it's a standard GM 4 pin HEI module inside the Lucas box). Have a look at the procedure for the injector pulse test (page 5 of the pdf).

The wiring to the ECU is a coax cable that looks like ordinary wire. As the insulation gets brittle with age the shielding wrap can short with the inside signal wire. If the ECU does not see an ignition pulse signal, it will not fire the injectors. Also check that the plug is seated properly on the terminals of the ignition module and making contact. It's possible the plug has simply come out of the module, that will kill the engine.

 

We charge a Service/Repair Hydration Fee for helping shops fix their cars. This fee is critical to supplying the forum's most senior members with sufficient recreational beverages to keep the ideas flowing freely.

 

DO NOT THROW PARTS AT THE CAR. THESE ARE SIMPLE CARS, AND SIMPLE ISSUES.

Losing the Injectoor pulse is common.

A few main reasons:

The Shielded coax wire from the Lucas AB14 to Pin #18 of the ECU is AWOL, more common than JD in a booze shop.

The TPS has died, VERY uncommon.

The EFI loom has failed internally. NOT common for the failure reasons given, they usually reek havoc for months before failing.

The multi pin plug on the EFI Resistor Pack, (RHF corner INSIDE the engine bay, basically behind the headlamp "bulge") Unplug that plug, CLEAN IT, and CLEAN IT again, AND the socket in the "Pack". Not as hard as the spark plugs, but getting there.

The pump is running, TICK, BUT, is it pumping fuel?????. Crack the Inlet double nut thing and take the required "FUEL BURNS" precautions, and see if you have a SPURT of fuel, or a DRIBBLE.

I need a bear or 3.

Then read the Sticky I wrote ages ago at the top of this section.

Work to a system, NO system, NO V12 running, FACT.

NO FEE, EVER, its an AUSSIE thing, and against the Forum rules, so clearly Vancouver has finally found his V12 sense of humour.

 

I just fixed my 88 jaguar xjs from a no start issue today but my car would not even turn over come to find out it was a lucas starter relay due to a clicking coming from the engine bay every time i turn the key in the ignition