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Check the wiring at the coolant temp sensor...the one for the ECU. If there's an open circuit the engine won't start. If the wiring looks OK, leave the plug disconnected and jump the terminals. This will simulate a 'warm' reading so a cold engine may not like it too much....but if it shows signs of life you might be on the right track
Have you pulled the spark plugs lately and checked to see if they are dry?
I am suspicious of the engine running for "one glorious minute" and then stopping. It may have flushed a bit of errant water still in the system and it got the plugs wet.
I have had series 2 and 3 engines get water in the system typically due to clogging of the water drain ports at the filler cap and it has been a real mongrel to get residual bits of water out of the fuel system.
I have also used methanol added to the fuel to pick up the water contaminants. The methanol will mix with the water and will also burn in the combustion chamber.
(Water/methanol mixture was used to boost performance and assist in cooling in large radial aircraft engines and also some turbine types)
Bill Mac
MK1
MK2
S3XJ6
X300
John,
Manifold Pressure refers to the amount of vacuum being created. Maximum vacuum created when throttle is closed (idling) and near zero vacuum with your right foot flat on the floor. This sensor, along with 305, 316, 311, and 310 tell the ECU how to adjust the fuel. I don't know the purpose of 326 or 349, maybe something to do with transmission kick-down. I don't own a Jaguar motor.
The system does not use any pressure sensing devices. Well....wait.....some versions had a high altitude compensator (not shown in your diagram) that was probably pressure sensitive as I don't see any other way for it to work. This was a mixture trimming device; not a primary control.
Throttle switches are tricky. There were at least a couple variants. On USA cars the switch was on the throttle spindle and (from memory) was operational at idle and at/near WOT only. I'll have to refresh my memory on exact function but it was another trimming device. other versions/market had different switches.
The diagram is missing a number of items that would apply to your '86 XJ6, if that's the car you had in mind in creating it
Doug,
Thanks for that.
My helper didn't turn up today, so not much done.
Cleaned up and poked around, looking for throttle wires. Couldn't find any. But did find Aux Air Valve with wires, so that makes sense.
Found a Mouse nest behind Brake Servo.
Took the plugs out, ready to turn engine over.
Plugs look good.
Attached is picture of injector ground, including Blue Wires which go to Engine ground (just to left of the bunch of wires) and Negative Battery Terminal.
I found the fuel pump relay and pulled off the connector. It almost crumbled in my hands.
Fortunately, I had another connector and after a lot of fiddling with it, took it apart.
And fitted the new one on to the Jag. The easy part was to make a plug in jumper to connect the white and white/green together.
Success!! Fuel pump now comes on with the ignition.
I am going to crank and crank the engine with no spark plugs to get rid of any old fuel/water in the line. And PRAY.
That is what I did last time for it to run for that glorious minute.
Now you mention it, the plugs were wet.
I have put "Sea Foam" in the tank.
To clear the drains in the Fuel cap, hit them with compressed air to blow any debris out.
I plan to crank and crank the engine to clear the water out. Hope it works.
you have an undiscovered component preventing the engine from starting and running.
I have a 1984 XJ-6 which sits most of the time and it always starts and runs.
I really would like to find out what that component is but I doubt it is the ECU or even wet spark plugs. You should see my spark plugs to understand. I have not changed them in YEARS. The old "leave dirty dirty enough".
The plan is to go to the ECU and take some measurements.
Hopefully that will tell me what the undiscovered component preventing engine from starting and running.
All the relevant wires are at the ECU and should tell me if I have no connection somewhere.
Just measured the resistance of Coolant Temperature = Open Circuit.
Found something wrong at last.
Question: Are there two coolant sensors, one for the ECU and one for the Gauge?
The plan is to go to the ECU and take some measurements.
Hopefully that will tell me what the undiscovered component preventing engine from starting and running.
All the relevant wires are at the ECU and should tell me if I have no connection somewhere.
Just measured the resistance of Coolant Temperature = Open Circuit.
Found something wrong at last.
Good work. You have something concrete to run with!
Question: Are there two coolant sensors, one for the ECU and one for the Gauge?
Yes.
The one for the gauge is easily recognizable as it has only a single wire.
The temp sensor for the fuel injection is third from the front as I recall.
Jaguar 1 John 0
So took off distributer cap. It was a bit crusty, no thing major, but cleaned it any way.
Cranked and cranked the engine with no plugs, If there is any water it will "blow through". Could actually see a mist inside the cylinders. So injectors are working.
Have nice white spark, too.
Found bad temp sensor, new sensor on order.
Time to go into trunk and check wiring to ECU.
Opened up the ECU and probed connections, The damn thing has a "lacquer coating", so reliable probing was almost impossible.
Then it was lunch time, (I am too old for this crawling around the trunk). I got terrible stomach pains and the wife called "911".
It was time to stop. Paramedics came and checked me out and I am OK.
Then for GP, we put plugs back in, manually triggered the cold start injector. Engine fired then died. Some ole, same ole.
So not a productive day. I need a rest.
On the bright side, my MG runs just fine. It's coming up for it's 50th birthday. Born late 1971.
