The troublesome one
Thanks for the reply, yes its a real pain!!

If you have a private e-mail address I can send a couple of video clips. I've tried doing it through the forum but I think the files are to large (26Mb and 39Mb avi) as they won't upload. But pictures do see attached.

 

OK,

NO sleep, thanks for that, this damn car is possessed.

I am going to a mates place today, and he has a ratted out PreHE in his back shed, I want to study the wiring ON an actual car. I have some thoughts, and he kind of agrees in principle, we will see.

PM sent

 

Sorry about the sleep situation!!!

One thing I mention briefly before, don't think it's related, when I used to fill up you'd always get a sucking sound from the filler cap when opening.
This doesn't happen now and there is a smell of petrol in the garage around the back if it's been in there a few days.

No sign of a leak anywhere

 

We then pondered the wiring diagrams, and came up with the following:

That 2nd NS wire from the 87 terminal of the pump relay goes to the Cold Start Relay terminal 30/51. Which, when the relay closes, supplies power TO the cold start Injectors.

I thought last night, that IF the cold start relay is staying active (welded contacts or other activation gremlins) then the cold start injectors are OPEN, and spraying copious amounts of fuel into each Inlet Manifold, and that is why it is running. NOT on the actual cylinder Injectors, but running badly on the spray from these 2 Injectors.

This jamming of that Cold Start Relay would also have a feed back, DIRECT to the 2nd NS wire on the Pump Relay, supplying 12v to the pump, and it will run via its own earth Black wire.

When the 85 wire is returned to the Pump relay, I reckon, ECU circuits are kicking in and stopping the pump, as designed for a NO start crank situation, BUT, I am NOT convinced yet.

I suggest trying to establish which NS wire at the Pump Relay 87 terminal goes TO the cold start relay, and unplug it. Then attach the Orange wire to terminal 85, and see it the thing starts.

Without power, the Cold Starts will be dead.

If it starts and runs, goodo, but I have my doubts, as I am still concerned with that EFI loom.

I am still trying to work out which wire is the "signal" wire to that ECU for Ignition Pulse Recognition (it is Pin 18 on the HE), and when I do, I will return, coz I reckon it is INSIDE that EFI loom that is clearly damaged. NO Ignition Pulse Recognition then NO Injector pulse (clicking as we call it), and NO engine running.

What all this has to do with a transmission test drive for oil leaks, I have NO idea.

 

Sleep is less required as we get older, so they say, and so I reckon 3 hours a night at my age is enough, HAHAHA.

Fuel tank venting will not cause this. It will stop the engine eventually, some many miles down the road, when the gravity feed of fuel to the pump ceases due to vacuam inside the tank, no air getting IN to compensate for the fuel going OUT.

Fuel odour after a few days locked in the garage, NORMAL, and can be addressed later if gets to you. The fuel hoses are probably "leeching" fuel, and so on, but, again, this has nothing to do with this pump oddity.

 

Hi

I tried taking wire 87 to the cold start relay off yesterday and it didn't make any difference, everything was the same. Hopefully you have received the video clips now and will be able to see that the fuel pump doesn't appear to be running. In clip 4 you can see the engine is hunting (I gradually reduced the revs to tickover and it started doing that) you can see there is no movement on the throttle linkage.

When I walk around to the back of the car you can hear the pump isn't running until I put the 85 cable to the neg of the battery, then the engine stops

Weird, Very Weird

 

PS found this online, very interesting all about the Djetronic system has the ECU wiring diagram at the end a bit fuzzy but may make sense to you
JAGUAR V12 FUEL INJECTION 1975-1980 - D Jetronic / AJ6 Engineering

 

If you have not done so already, I think you should check that the pump is correctly wired, and that the positive feed is on the positive terminal. Some pumps will run backwards and produce pressure - for a bit.

 

Thanks Greg

I will check that, however no work has been carried out in that area so nothing should have changed there

The original fault was that the car stopped as if turn off with a key and when it does run now I can stop it instantly by connecting wire 85 back on to the relay to bring in the pump.

Hopefully Grant will be able to post the videos and it will seem a lot clearer