Purchased a 1985 Jaguar V12 no start for 350 dollars with wires unplug as well as things missing ( see attatched photos ) been reading alot of post from all of you on here thanks to all the post
I reconnected what i learned so far and replaced spark plugs gapped at 0.025 as well as the wires, fuel pump fuel filter and some fuel lines
wasnt able to get power to the pump at key position 2 or 3 but was able to get power to the pump by running a wire from the ignition amplifier to pin #18 of the ecu ( 6cu) will be upgrading that to a 16cu as some research says they are better,
so here is where im at and need help

-now i have spark and it fires up for about 5 seconds or so injectors are not firing and i also want to know if anyone could help me figure out the vaccum advance hoses and where they go and also how to get the injectors to fire up, oh yeah i had to delete the cats because no airflow was able to get through thats when it fired up

would greatly appreciate it.

 

Welcome to the forums Justin,

I've copied your question from New Member Area - Intro a MUST to XJS forum. Members here with the same model will be able to help.

Graham

 

appreciate that Graham thank you still learning how to navigate this website. so bare with me

Justin

 

Are those hotos showing how it is while you are trying to start it?

 

no it is of how it was before when i bought it please see attatched video of where i am at now.

thank you greg,

 

v12 lets go

 

thank you

 

the way it was in the photos was how i got the XJS but the way it is in the attatched video is the way i have it now,

thanks

justin

 

Injectors not firing could be a connection fault in this wire, the one with the bullet connector coming out of the amplifier going into the loom on the right:



Check that the connector is clean and that the wire going into the loom is not cracked or cooked. If it is tell us, as there are things you can do involving stripping back the loom wrap and seeing what is under it.

There is a resistor pack on the A bank side of the engine, clean the connector both sides, here is an explabnation:
https://www.jaguarforums.com/forum/x...sistor-134745/

Not saying these will cure your car, but they are all things that can cause it and worth doing in any event.

I am worry that the fuel pump will not work normally on the key. You said "wasnt able to get power to the pump at key position 2 or 3 but was able to get power to the pump by running a wire from the ignition amplifier to pin #18 of the ecu ( 6cu) will be upgrading that to a 16cu as some research says they are better"
Where exactly on the amplifier did you get the power from to send it to pin 18? Please explain.
This fix indicates the ECU is not getting the right signals when the key is turned, so it could also be that whatever is causing the ECU to not run the fuel pump is also something to do with the injectors not firing. Do you have the wiring diagram for the igniton and injector and ECU circuits?

If you turn on the key, and then, leaning over the engine turn the capstan, do the injectors click? If they do this is an indication that the ECU is getting the signals.

Let us know what you find. I will throw a rock on Grant Francis' roof and we will see what he has to say, as he is the guru on these 6CUs. Incidentally a 16CU is a great idea, just pluig and play, no changes needed.

 

OK, from way down here, my thoughts so far.

You have spark and SOME bang juice, goodo.

The Injector pulse is missing, as you have stated.

That resistor pack male/female plug cleaning is a MUST do, regardless.

Once clean and replugged, turn ON the Ign, rotate the throttle capstan (as if taking off quickly from a stopped position). You shoukd hear Injector "CLICK".

If so, the TPS is working for now, more on that later.

If NOT, then the TPS may be in need of resetting, replacing, etc.

BUT

The CTS (Coolant Temp Sensor), located juts aft of the B Bank themostat, on the alloy housing, with an Injector style plug. NOTORIOUS problem child, as is the wiring INSIDE that boot/plug.
Quickie test, unplug the CTS, take a paper clip, or similar, and bridge the 2 terminals IN the plug. This will fool the ECU to a Hot engine, and it will run IF that is the issue. Remember, The CTS is a Prime fueling signal, SOOOO, running V12, unplug the CTS, = DEAD V12, its that critical.

ALSO

The CTS and ATS (Air Temp Sensor), nearby, have the same plug, OOPS, and can be wrongly plugged in, = dead V12.
If in doubt of yours, due to Freddie Fiddler before you, bridge BOTH plugs, you got your backside covered now.

Let us know the outcome, and we will work further if needed.

 

so when i turn the i get the fuel pump to turn on for about 5 seconds
than it turns off, i also hear one loud click from the injectors with throttle all the way down on position 2

also when cranking fuel pump runs to

 

The Injector pulse is missing, as you have stated.

That resistor pack male/female plug cleaning is a MUST do, regardless.

Once clean and replugged, turn ON the Ign, rotate the throttle capstan (as if taking off quickly from a stopped position). You shoukd hear Injector "CLICK".

If so, the TPS is working for now, more on that later.
the list im going through today ill let you guys know the outcome.

thanks


If NOT, then the TPS may be in need of resetting, replacing, etc.

BUT

The CTS (Coolant Temp Sensor), located juts aft of the B Bank themostat, on the alloy housing, with an Injector style plug. NOTORIOUS problem child, as is the wiring INSIDE that boot/plug.
Quickie test, unplug the CTS, take a paper clip, or similar, and bridge the 2 terminals IN the plug. This will fool the ECU to a Hot engine, and it will run IF that is the issue. Remember, The CTS is a Prime fueling signal, SOOOO, running V12, unplug the CTS, = DEAD V12, its that critical.

 

Please repost, the list is invisible!

It is good news that the injectors click, this definitely means the problem is getting narrowed down.

 

GOODO, that is as designed.
The TPS is talking to the ECU, which is talking to the resistor pack, which is talking to the Injectors, SIMPLE.

The question NOW is, are the Injectors actually squirting fuel. Just because they "click" never means they are opening. RARE, and I mean RARE, that all 12 are dud. They fire in 4 groups of 3, so even with some working the thing should cough and fart a bit.

That shielded wire to Pin 18 of the ECU is the Pulse signal for teh ECU to operate the Injectors. Basically stating there is Ignition activity up front, best we fire those Injectors. Like a Tacho pulse. You say you ran a wire to Pin 18, so maybe that is OK, but without that pulse signal the Injectors are DEAD at cranking etc.

Read the attachment. I have NEVER had an issue with the "blob", but there is always a 1st time.

 

Not much to add to what Greg has said as he's covered the critical basics. How's the quality of the fuel and fuel pressure though? Just to expound on what Greg has noted, the Igniton is upstream of the EFI system on these cars and the EFI system (as noted) requires that RPM pulse from the Amp via the white shielded wire to pin 18 of the EFI ECU in order to calculate injection. With key on- the EFI ECU will control the fuel pump relay (ground it) for a couple of seconds if the normal routine is working just to pressurized the fuel rail, BUT WILL NOT re-engage the fuel pump unless it is getting the +12V signal from the starter relay during start and then the RPM signal as the ongoing reason to keep the relay grounded. Since you're into resurrecting this car, it might be wise to splice in a fuel pressure gauge between the regulators and look for something around 30PSI at all times (you'll need to replace all the hoses soon enough anyway). Clogged fuel filters or a non-reengagement of that relay could make for starting headaches. Just a small technical point: The EFI ECU is essentially 2 channels. Bank A and Bank B. The wiring IS split as 4 groups of 3 injectors (2 groups of 3 per bank) but inside the ECU each open and hold circuits are fused into an A and B bank on the circuit board. Greg was right about making sure there is good contact at the power resistors as although the car can idle sometimes on the "open" circuit only (direct current flow), the EFI ECU can burn out and can't handle larger pulse widths without handing off each injector control pulse to go through the hold circuit and the current limiting resistor pack (for hold milliseconds of each injector pulse operation).

~Paul K.