I have gone through everything that I can think off, and Grant and Greg have gone places I wouldn't even think of going. Im glad you rebuilt the FI Harness regardless if that was the issue, I thought it was, wrong again! One thing that does sort of bother me is you said with the harness unplugged you get voltages as they should and plugged in you don't? Have you checked all your injectors? is one burnt/shorted giving you grief, The only other things is the water temp sensor, checked that, I don't remember if you had being there or not and not prepared to re-read all the pages.
You know its funny with the time and effort "I" would have seriously and I mean seriously looked into using a megasquirt, haltech or wolf ecu and controlled fuel and spark, it would dump the dizzy and all the Lucas gear, then watch it go.

 

Thanks for respons,I did check ats,it has 4.89v to y/b wire.The cts has 3.68v not really the 5v but like Grant said should be ok.My Tps checks good.My fuel pump is new and runs while cranking eng..So all that checks.
The thing with the multi plug at inj harness is baffling.I ohmed each inj individually and nothing grounded.all injs have ohms.I hooked test light to the orange wires on chassis side plug (unpluged).It doesnt light or pulse test light when cranking eng,but if I use my vohm meter.I get the 4.9 on those orange wires.and when cranking eng my meter goes crazy up and down in voltage.But like i said everything changes when inj harness is pluged in.then all wires have 12v..
im going to do Grants wire switch on ign and see what happens.
If no change then I'lll check each inj at harness plug,unplugging each inj one at a time.
thats all i can think of right now..
Then if nothing works,I would appriciate more info on the upgrades you mentioned Katoh,Thanks for that info.

 

Ok I was going through some schematics,and came across a digital P fuel inj diagram of saloon 1981 and above years V12. I noticed on the shielded signal wire,pin # 18 from ecu to ign amp.it shows a resister 6-8 ohms connected inline up at ign amp.Its not shown on any other schematics Ive looked at.My car doesnt have this.I also noticed this on the pictures Greg in france posted on page 11 of this thread.
I also noticed on my car when tacho wire and signal wire to ecu is hooked up.I have 6v on tacho and 12v on signal wire.Now,If I switch the wires,no matter what I still have 6v on tacho and 12v on signal wire.I would think I need to put some type of resister on the wire comming out of amp to signal wire to ecu.Unless its not the case on the HE xjs. Anyone???
so where can I get that resister anyone know?

Udate,no change when switching ign amp wires.Tach and ecu signal.
Does anyone know if there is a way to check signal to ecu?
There is 12v to pin#18 from the amp,Dont know about when cranking eng.

 

A lot of info to digest I know but want to keep evryone up on things.
I ohmed out wiring harness I built.I must have done someting wrong,please correct me if this is wrong?
I disconnected multi plug to inj harness.I disconnected injector plugs 1a 5a 3a from injectors.I ohmed from injector harness plug to corresponding wires.On injector 1a both sides of injector plug to inj ohm to k/b
only one side should ohm to k/b the other side is o/u so something is crossed.time to tear out inj harness and start over..

 

The best site to look at rebuilding the FI harness is FI Harness Rebuild Use the diagram about a 1/4 down the page that shows the wiring for all twelve injectors, then use the plug picture he has to run the wires to the harness plug, the other smaller plug on the harness is for the two cold start injectors and the temp sensor. You will see there is also 4 commons in the harness I know it makes no difference but when I did mine I put the common always to the left side of the injector plug, just to be sure to be sure.
Follow his plans you can't go wrong.

 

thanks,I wont be so quick to construct it .Now Ill see what I crossed with what.

 

I have just be revising the Great Palm's book on the fuel injection system. If you have not read it, I realy think doing so is a very good idea. It has all the steps in it of what can go wrong, including with the ECU/resistor pack/injector wiring stuff and how to test it.

One easy thing that is mentioned is the earthing straps on the radiator cross panel securing bolt RHS, not far from the resistor pack. If this earth is not 100% good the injectors will not fire properly, if at all.

Secondly, one wire out of the two of the injector loom should carry 12v to each injector. But the ECU does the switching to earth. SO, if I have this right in my understanding (no guarantees) the system is a bit like a light circuit where the sequence is as follows:

Battery + sends 12v down a wire to a light bulb; then wire goes from the bulb to a switch; then wire goes to the battery - to make the circuit. In such a setup there will be 12 volts available EACH SIDE of the light bulb UP TO THE SWITCH at all times. But the light will only go ON only when the switch completes the circuit. If you earth the wire between the bulb and the switch even though the switch is off, your meter will show 12v present (and the bulb will light up) as you are effectively bypassing the switch.

The test you really need to do is to see if the ALL injectors are working when the car is being cranked. To do this you can (a) put a meter across the injector connector terminals one at a time and get someone to do the starter. Then with al the plugs back on the injectors, repeat the cranking and this time use a mechanic's stethoscope and listen in turn to each injector to ensure that injector is actually clicking. Thus proving (or not): (a) there is switching on and off and (b) the injectors are mechanically responding.

Greg

 

If you are saying that BOTH sides of one injector are connected to the same wire (rather than one wire carrying the 12v and the other wire returning to the ECU earth switching system), yes, this is a wiring error.

Greg

 

Palm's book link:

http://www.jag-lovers.org/xj-s/book/Jaguar.html

greg

 

Thanks for that Greg,I will read it.
and yes that is whats happening here.I tied in two groups of three,it made 6 injector plugs cross wired so all those injectors where getting 12 volts to both sides.A critical error.
I have inj harness off and repairing it.
Also when you say earth straps at radiator,do you mean the black wires at top of radiator that attach to the top plate of radiator?If so yes I cleaned at secured them tight.
Thanks again,I'll update my situation later today

 

Ok,What a cluster f... I rebuilt the harness just like the old one.
I dont know how car ran to begin with.
Acording to the wiring diagram Grant sent me.(thank you again Grant).
The harness is wired wrong.the 6A inj plug should be K/B and O/W mine is K/B and O/ U
all wrong.so I have to sort to colors.

 

Been following this for a while and whilst I can't offer any technical help you have my support; keep plugging (ha, ha) away and you will get there.

 

Ok,I went through the harness inch by inch.It is correct.When I pluged it all in I mixed up 5A and 6A and 5b and 6b. So I put the harness back on car.I have 1A and 1B out so I can see if they spray fuel.
When I turn ign on,the 1A injector sprays big time.Not the 1B nothing.
Now since 1A ,3A and 5A are tied in Im assuming they are spraying too.Without removing fuel rail and lifting it up,there is no way of telling.
Now if I can just get the B bank to spray everything would be great.
One Other thing.I dont see any cold start injectors on this car.
So when ign is turned on,shoukd the inject spray once for primming or???
Anyone with Ideas??

 

So there is no signal going to the B bank at all? Try just unplugging the injectors one by one using a test lamp and see if its getting a pulse.
The cold start injectors are directly behind the throttle bodies on the Plenium, I'm not sure how many times they come on or spray when its cold but I know that If I leave my B bank connected it backfires when it firsts
starts big time, all they do is shoot of a mist of fuel directly into the intake manifold on each bank.

 

Well I cant find cold injs but can smell the fuel while cranking,so must be working.
I tried the test light to the Orange wires on each inj no pulse unless it really fast and I cant see it.
Ok Katohyou where saying that that one side if injs get 12v,and yes i have that to all injs,that comes from K/B wire from main relay.
I also have 12v on all the Orange wires if Injs too. So like i said,all inj plugs have 12v to both sides for some reason.But yet the 1A inj was spraying when key on.
cant figure whats going on.
Is there another test that can be done?

 

Catching up, so bear with me.

Your car NO GOT cold start injectors, normal.

NO injectors should "fire" at ign ON, so something is out of whack here. Only cold starts IF fitted.

Those resistors you mentioned up there a tad are INSIDE the rubber blob of the amp. There are 2 in there, and I forget the specs at the moment. 1 is for tacho, the other is for ECU pin #18. They are different values. If the tacho one dies the tacho ONLY stops. If the ECU one dies the engine stops DEAD, coz the ECU has lost that pulse.

 

Ok,So with ign on no cranking,no injector should spray.Only while cranking engine.I underst that.
But mine is spraying,but not everytime i turn on ign.about every three or four times.
If I take apart the ign amp,and ohm the resistors inside will that tell me anything.?
And if I have no cold start injs how does eng prime to start?

 

The resistors in that blob will either have a reading, or not. Someone may know the specs, I dont at the moment, but will look when I get time, and that may be a day or 2.

No cold starts is GOOD. The engine fires the injectors as you crank, as you know/said, and it only takes a whiff of fuel to fire that thing up. Also that "fast opening" of the throttle fires all 12 ONCE, and that can also be used to aid starting in very cold conditions, and also to aid hot starts.

 

Grant, were cold start injectors an option or only fitted to certain cars? both my motors have them and their both 83,s. Aus Import.

Jagernut, you must have a short again if the injector is firing with just the ignition on, I believe Grant said earlier that the injetors where earth/common switched from the ECU. try setting your multimeter to ohms and check the earth/common side of the injector harness wire to the body, if you get a reading you have the common wires shorting some-where's before the switch. That also means when the ignition is on all the injectors should have power, if you take a seperate wire from the common side and touch it to the body the injector should fire.
Ill try and get a chance tomorrow and record some readings of mine, to make sure and post them so you can compare.

 

Great, Thanks Katoh,That would help compare things.Ok,when you say common/earthed im assuming you mean all the orange wires (4) in the harness? I did check all the wires on the chassis side side of harness and injectors side,nothing is grounded.I checked it on 200 ohms to 20K setting.
I have two ecu's when I plug in one of the ecu's The 1A inject will spray once,ign on not cranking.and not spray when cranking.
when I hook up the other ecu,the fuel rail still charges,but inj doesnt spray.Ing on or cranking. so not sure if problem is ecu related.
Is there a way to check signal wire from ign amp to ecu while cranking eng.? Will there just be a steady 12v while cranking eng on that wire?