Just caught up again, damn I must retire again.

I will go thru some things, in NO particular order, that is for the more awake to do, and the JD is tempting me at the moment.

I concur with what I have read.

The fact that 1A, and who knows which other injectors, actually "activate" as the ign is switched ON, has still got me a tad stumped.

There should be NO activity.

With that ign ON, and the TPS snapped open, do the injectors pulse?.

That has my very tired brain heading in the direction of: loom, TPS, CTS.

I would be bridging the terminals in the loom of the CTS, just for giggles. It is a test I use for no start, and is easy and free to do. If that proves nothing, replug it for now.

I would then unplug the TPS, turn on the ign, and note the spray or no spray. For some dumb Aussie reason, I still have doubts on that TPS.

If the injectors are dead with the TPS unplugged, go for crank. The ATS,CTS are still talking to the ECU, as the splice wires are on the chassis loom.

However, you then state if you mess with the timing, the thing starts and dies. This I believe is the engine running almost like a diesel, from all the fuel getting somewhere near the spark, and lasts a few seconds, as no more fuel is arriving to keep it running.

You also mentioned it has been laid up for a "while", which begs me to ask the following:

How long laid up?
Was it "driven" into lay up, or pushed?
Any other info related to the reason for lay up that may indicate, or may not indicate, this issue was the reason FOR the lay up, please.

You may have 2 ECU's that are toast. My reason for that statement is that the ECU in your year model is "maybe" the 6CU spec unit. This unit had issues with the fuel pump circuit, AND the injector drive circuits. By the basis of this enormous thread I reckon the ECU has been given an electrical belting, and so maybe has the other unit, as you have found some serious wiring issues of late.

The later 16CU unit is a direct "plug and play" ECU, and is more robust in those areas, and others, and also processes data about 5 times faster than the 6CU.

 

Thank you Katoh,I will try it that way and see what happens.
I have to leave for a few days,but will be back at it when I return.
I will try this today and let you know what happend before I leave
thanks..

 

Yes it is baffling,
The Tps checks out as of testing,no inj clicking when snapping tps open.
I'll try unpluging tps and see what happens when cranking.
The inject 1a only.sprays sometimes not everytime.
I do have the cts jumperd.Still the same.I checked all voltages at ecu.
I did that test on the injectors I mentioned in the previous post.And all injectors pulse,I checked each one.
so it doesnt make sense.If it wasnt for 1a spraying sometimes.I would say all injectors are pluged.
I know I have good fuel pressure.
The car has been sitting for about seven years.I had it running good just three weeks ago,so dont understand what happend.I drove car about 500" and noticed hard brake pedal.I parked car,shut off eng and checked out brake booster.Someone had the check valve in vacumm line that comes from other side off eng intake,backwards so no vacumm was getting to booster.I turned it around as to have booster for brakes working.Thats all I did.then the next day this mess happend.
I'll test injectors again and see what happens..

 

Ok,Here is what I found.with inj rail raised up ,to see inj operation.Ign on No cranking eng, all A bank injectors stream fuel for about 3 seconds,as fuel rail is charging.No B bank inject release fuel.None of the injectors spray while cranking eng.
I have all sensors and tps working,Signal from ign amp must be getting to ecu,cause I have pulse so my deduction goes toward ecu circuits bad somewhere.??

 

well,I checked each injector,one by one with 9v battery.
when i turn on ign sometimes one or all inj on A bank will spray fuel,when that happens,I can check any inj with the 9v and here it click but no pressure in rail to spray fuel.
If no injs spray at ign on,then if I check any inj with 9v it spray's
So due to pre inj spray at ign on,yheres no pressure at cranking eng to spray injs.
My analysis anyways.
From my understanding,if fuel rail looses presure should fuel pump come back on to charge rail again?

 

This is like War and Peace!
Yes, the pump should come on if the pressure drops in the fuel rail
This is a very long thread and an awful lot to read so apologies if you have covered this; have you checked the fuel pressure regulator? Disconnect the main fuel feed from the regulator and get a clean container, stick the hose in it and fire up the pump.
If there is a good steady supply then the pump should be fine. It is possible that the regulator is failing once the rail is pressurised and not allowing fuel through once the pressure drops off as the fuel is used.
Just a thought.
.

 

Very Good thought,I will try that.
I know when I disconnecting both vacumm lines on each pressure regulater,after cranking eng there is no fuel smell or visible sign of fuel leakage,in vacumm line.
So diaphram seems good.
thanks for the suggestion.I'll let you know what I find.

 

Ok,heres some new info.
I disconnected fuel inlet at pressure regulator.put the fuel hose in measuring jar,the one ecu I have hooked up now,supposedly good,when ign on only realeases about 5 oz of fuel.When I hook up the other ecu,supposedly good,Ign on it releases 8 oz of fuel.But this is the ecu that when ign on,and I unplug harness to injectors,and check the voltage on plug chassis side to ecu.All the orange wires have 4.9v and according to Katoh's findings on hes car they should be 0.0 volts.all pink and black wires have 12.5v still.
Now with first ecu mentioned pluged in,all pink and black wires have 12.5v and all orange wires have 0.0 volts.
I think each ecu has its own problems.Anyone know How much the pump should dispense with ign on?
Also,what makes pump come on if pressure in fuel rail drops.?
Fuel regulators have no sensing wires to give ecu signal to release more fuel from pump.Is it on fuel rail??

 

Jagernut

I need a clear summary of what you are 100% sure you have fixed, as I am a bit lost now.

• Is there 100% definitely a spark?
• Are you now 100% sure the injector loom is correct?
• Are you sure that every injector is unblocked and functioning?

FUEL delivery:
I suggest you:

• bypass the A bank (US passenger side) fuel pressure regulator. I does nothing and MAY, repeat MAY be a factor
• Pump pressure: Having bypassed the regulator, get a friend to hold a hot wire to the pump while you, using a length of flexible hose, direct the flow from the engine bay pipe that goes into the fuel rail into a container. ANYthing less than a HUGE flow of fuel is a problem.
• If there IS a problem, work carefully though the system from the main tank outlet, to the sump tank, sock filter, pipe to pump, change the filter, blow out EVERY fuel line and try again. If still a problem, change the pump.
• Once you are sure the pump is delivering pressure, reattach fuel pipe to injector rail and pull one of your 100% working injectors. Then hot wire the pump and hot wire an injector and make sure it sprays REALLY well. This should prove you have rail pressure and that the B banl (US driver's side) pressure regulator is working properly.

Once all this is 100% done and you are 100% sure you are down to electronic problems. I am worried about what you wrote about the CTS. Have you actually installed a new one, they are dirt cheap ? If not do so, jumping/rewiring etc etc cannot be a 100% sure fix. Finally, are you 100% sure that your TPS fix is 100% ,


If you can answer all these as done, we MUST be close to finding the real problem.


do not lose heart, you will love it when the car goes again.
Greg

 

War and Peace is a paperback in comparison.

There is wire from pin C4/C1 of the starter relay to pin #26 of the ECU. It is White/Red, SAME as the starter solenoid wire from the same relay terminal, but smaller diameter. This wire TELLS the ECU to fire the injectors, AND start the fuel pump whilst the ign switch is in the START position.

Once the engine starts, the "start" position is de-activated, and the ignition pulse is sent down the coax wire from the amp, and takes over that "telling" to the ECU.

Its that simple.

The fact the injectors do not operate with the throttle opening, still has me thinking in that direction.

The odd activity of the ECU's is strange, even to me.

 

I agree,this is turnning into a best seller.
I would still like to kick that lucas square in the back side.lol..
Ok,the wire you are refurring to that goes from star relay to pin 26.
That wire has 12v when cranking eng?or with ign on?
As for tps,with ign on I have .34v at the red wire on tps to ylw/wht spiral.on closed throttle.
With throttle open 4.89v.Also 4.99v at green wire tps,to ylw/pink.So I think that falls between specs.
My big problem is.Why if according to my vmeter hooked up,cranking eng.The injs are pulsing,but I hear no clicking.And due to the fact that A bank inj spray at ign on (sometimes) I believe this action depressurizes the fuel rail so injs dont spray at cranking eng.
my silly deduction.
So with fuel inlet to eng,disconnected at rht side pressure regulator.I turn ign on I get 5oz fuel,in a container.Now when cranking eng,shouldn't fuel pump run again??

 

Ok,In response to greg in France.
yes the inj harness is correct,I checked it.
And yes all injectors are spraying a good stream of fuel.when I jumper them.
And I have good spark.
Good points by the way..
I will try the test you mentioned,and let you know.I did just replace pump and filter,and cleaned out small sump fuel tank and sock strainer.
as far as tps.I mentioned my findings on last post.It seems to check out.
Thanks again guys for all the help.Its really appriciated..
I am verry determined to get this car back to running.
Oh by the way I found a 16cu unit out of a 86 xjs online that has been tested and has 30 day guaranty.For 100.00 US

 

Ok,first off the white/red wire from starte relay to ecu.with ign off or ign on 0.0v.while cranking eng,It fluctuates from 0.0v to 13v
Now,I took both ecu's (6cu) laid them side by side.
ohmed the pins to the casing,one by one,and compaired them both.
Both ecu's are the same except for pins 2,3, and 20 ecu #1 has 0.00 on those pins, on a scale of 20K ohms.ecu #2 those pins show open on same scale.
So my point is they should be the same on both ecu's.
If anyone has a good spare ecu 6cu if you can ohm your pins like i did,to ecu casing 20K, and see what you come up with.
One of my ecu's are bad or both.
thanks

 

BUY IT NOW

Greg

 

I think that say's it all...
I was reading on some post here that some 16cu's dont work on 6u models.Is that true?
This one is for 86-89 its a 84526B DAC4118. will it work ok on my 84 plug and play...

 

NOT true. The 16 CU is a direct plug in replacement.

Greg

 

Ok,Thats all I needed to know..
thanks..

 

Adding to the post further up from you.

With the starter in operation that pin 26 should see a nice clean 12v, or very close. Fluctuating as you mention indicates burnt contacts inside that relay, which would confuse the ECU something fierce, as in on/off/on/off. Easily cleaned, OR replace it. They do take a belting, especially with an engine that fails to start.

I dont have a spare ECU, but looking at the schematics for USA cars that I do have it shows pin # 1 2 16 17 34 are ALL earth connections, direct. Not via the casing that I can establish, but may be incorrect.

 

Grant, which relay is that please? Mine was a tad hard to start yesterday! OK Grant, got it, the starter relay, I found the original post!

greg

 

Dear 'O' Dear, turn around for a minute and you miss a week on this thread. LOL
So its either back to the ECU or the pump relay.
Well one good thing is now you are 100% your injectors work, the wiring is good and spark is there too. its come to its either one or the other now. Ill be watching to what happens next. One good thing is while your doing all this and I'm going checking things on my car I found a fault on mine while looking for something for you, Cheers for that.