bought my jag for 350 bucks. i got no fuel injector pulse with a noid light. i have power on both terminals of fuel injector plug. car came with 2 ecus. i tried both. any suggestions? i read thru a chiltons manual but its very vague.

 

Any additional info from the previous owner ? Its always a challenge buying a non running car

Are you getting a spark ? (This will help in pointing you what to check next)

Crank sensor comes to mind, which I think would be confirmed if also no spark.

 

Check the wiring at the ignition amplifier. Perhaps the "trigger wire" isn't telling the ECU to go to work. It's probably a white/black wire but I can't say for sure.

There are other possibilities but I'd start with the amp wiring.

No crank sensors on an '83, by the way, so you have less to worry about :-)

Cheers
DD

 

guy is dead so no info. he messed with everything. i didint find a 3 wire plug for a trigger wire on distributor like i read in service manual. just a two wire plug out of distributor for a spark amplifier. spark amp is gone but car does have spark. i have spark, fuel pressure, no injector pulse.

 

What was used to replace the original amp? Is there an out-of-place looking control module or anything like that that you can find? if so, can you trace the wires?

"Something" needs to be in place to trigger the ECU

Cheers
DD

 

well i have a two wire plug comming out of the distributor that goes no where. guy messed around with the wiring harness so i have no idea where it goes. i feel like this is the problem. the spark amplifier is missing from the top of the manifold.

 

car has an after market msd fire ball mounted to the firewall but its not hooked up. i do have spark though. car will try to run with starting fluid.

 

One thing that helped me determine whether it was the ECU or not was listening for the fuel pump. If it cycles on at key on, but not while cranking, then the ECU is working but doesn't know when the engine is spinning. Which in my case pointed to the crank pickup. That was on my '88. The more knowledgeable guys may correct me if it doesn't apply to the 83 or 79 xjs.

 

Not 100% sure about a '79 but later models have a "injector ballast" pack (sometimes known as a "resistor pack") to protect the ECU in the event of an problem in the injector wiring (itself not unusual).

I'll see what I can find out about the earlier systems and post back late.

Cheers
DD

 

The failure of the fuel pump circuit on the ECU is well known but it doesn't influence injector pulse. Good thought, though.

Since yours has a crank sensor it must have Marelli ignition which wasn't used on the earlier cars. You'd be on the right track, though, on a later car because dead crank sensors will disable both injector pulse and spark.

Cheers
DD

 

Well I wasn't referring to a FP circuit failure, only using the the operation of the pump to determine if the sensor that tells the ECU the engine is cranking is bad. My car is Lucas so I guess to be more specific it was the speed pickup in the distributor. Actually it was you that helped me track to down my problem Doug in 2004, via xjs-lovers. Thanks again.

 

I see what I missed. I was responding to the first poster, not the last.