Hey everyone, ive been searching the web
looking for some answers and not having alot of
luck so figured id register and see if anyone
could help. I picked up an 85 xjs h.e. 5.3L a few days
ago, previous owner said he bought it for parts
for his dads car however it was 100 percent
complete and it ran on starting fluid. Only
thing was is that it had no injector pulse. I
confirmed it and had it running on starting
fluid twice and it purrs like a kitten. I have
not checked injector harness with noid lights
but im assuming since there is almost 30psi to
the rails at key on and while cranking that i
have a pulse issue. I have checked continuity
between every circuit from injector harness
connector and power resistor connector to the
ecu with less then a half an ohm on each
circuit. Injector harness itself is good from
the connector to the injectors itself. Nothing
shorted to itself or ground. Took power
resistor apart and didnt see much, cleaned up
terminals on resistor and connector. All
injectors ohm out at 2.5 ohms. Injector pulse
trigger wire has continuity from ign amplifier
to ecu and coolant temo sensor ohms out fine as
well as the harness to the ecu. This car is
starting to drive me mad. Any input would be
greatly appreciated. Thanks in advance, chris

 

You've probably checked but I don't see any mention of it......

But....

Do the injectors have 12v supply voltage from the 'main' relay? This is on the pink/black wires


Cheers
DD

 

Yes, i have power at the pink/blk wires at the connector before the injector harness and on both pins of all 12 injector connectors

 

Welcome.

Also, Ignition ON, engine OFF (haha), silent area, so NO steroes etc, and turn the throttle capstan "quickly" to Wide Open Throttle. Just as you would for a quick getaway.

You SHOULD hear the 12 injectors CLICK.

This confirms that teh 6CU ECU is doing what it should. The 6CU is fraught with issues, Mainly fuel pump earth circuitry, but age is now showing injector pulse issues as well.

That signal wire from the ign amp unlt only takes over once ignition pulse is available. There is a supplemantary wire from the starter relay to "wake up" the ECU during cranking, and that can be a dud due to dirty contacts inside that starter relay.

CTS wiring, about 8" from the CTS itself, is spliced, and I have had a couple where that splice is broken.

This pin out table may help you a tad.

XJ-S ECU Pinout table.doc

 

Ok, so i broke out the stethoscope and listened to each injector and about 9 of them had a loud distinct click. 3 were iffy at best. Plugged everything in and cranked it over for kicks and giggles and it decided to fire up. Definitely a little rough but im gonna seafoam it tomorrow morning and see if it doesnt clean up a bit. It was smoking like a freight train from the engine bay from sitting for 8 plus years but hey for 350 bucks what did i expect right?

 

Thanks for the quicks responses and the knowledge too guys, i appreciate it

 

Well done.

Another V12 back awake, simple engines, stong as hell, really.

 

Ok, put some sea foam through it just to clean it out a little and it seems to have worked. However i still have two dead fuel injectors. Would anyone happen to have a couple laying around that they would like to part with?

 

Aussie fix.

Get a hammer, are SMALL/TINY hammer. NOT a BFH.

With the engine running, tap the lousy injectors CAREFULLY, and you might just be lucky.

It has worked for me many times.

I try to get down to the metal section, and sometimes a drift is needed to get down there, but tapping the plastic top section will do little.

Obviously some good old common sense applies here, and since you have a V12, you must have common sense.

If it dont work, its cost you zero.

 

If Grant's suggestion does not work, removing them and soaking them in injector cleaner overnight might work. I bet they are glued shut with petrol residues. Or even disconnecting the fuel regulators and pouring the rail full of cleaner and leaving them all to soak.
Greg

 

I was going to try something to that effect but wasnt entirely sure if that would do much. Figured the pintle was glued shut from sitting for ages. Ill definitely try out both options before i pull the trigger on some new ones. Im in no rush to get the car on the road, just tinkering with it in my free time. Thanks again guys

 

New ones, oh boy, that will be some serious drinks money gone there, IF they are still available.

I had some PreHE ones that were giving me the creeps, and the hammer worked, sort of, but the fuel hoses were so so anyway.

I pulled them, got a large coffee jar from "her' stash, and put the injectors in it and filled it with good clean diesel fuel.

Next say, I set them on the bench with a hose attached (about 2 foot long), compressor nozzle in the end of said hose which was filled with Paint Thinners, and a 6 volt lantern battey for power, and then "ON" the injectors as I pushed the nozzle button.

Filled the hose with thinners again, and zapped them again. 10 came up sweet. 2 went back in that jar, and next day, repeated the blow out, took a bit, but they came good.

Sir Arthur (the S2 V12 in my "garage") has now done 300K kms on those "cleaned" injectors, and has never complained.

Cost: bugger all. Satisfaction: priceless. Drinks money retained: not countable.

 

Well, plenty of drink money left over For tonight! Just got home from work, grabbed a hammer a prybar and my trusty stethoscope gave those injectors a couple good smacks and they started clicking away. She's running great now. Gonna do a basic tune up, top the trans fluid of and hopefully be tooling around town by the weekend. Thanks a bunch for all the advice guys, much appreciated

 

Told ya they are SIMPLE cars, and people still have doubts.

ENJOY.