Hey Gents,
Update on the fuel all the way to the rail, It turns out the previous owner has installed a 12 volt electronic ignition. Allison XR-700, could it be a bad LED? However, Grant has told me the reliability factor of the 12 volt system, I now find myself on the front panel just behind the headlamp assembly unbolting what appears to be 4 grey wires grounded, splicing 1 fully chewed through rodent style, and 3 half chewed. I can only pray now Boys that my problems are at a close with no pulse. Please continue to give me the hopes that I need to see this through, since the age of 10 I have wanted one of these Coupes...
Also thanks so far for the trouble shooting tips, I will Post my photo shopped aerodynamics plans for my 200 mph goal. Thankful to have the support, and truly grateful.........

 

do you have spark?

 

Yes, I have spark, runs on ether, starting fluid, have pressure to rail as well.
1976 XJ-S
Stephen

 

check that you're getting pulses through the engine speed sensor on the ecu. I think it's pin 18. I didon't remeber exactly. this happenee to my car and I solved it by running a new wire through the car to the ecu.

 

Thanks a bunch I will give it a shot.

 

I dont think the 3CU PreHE has that sensor signal?. It has been a while since PreHE darkened my door, but pin 18 is the signal wire on a HE 6CU and 16CU unit.

The Crane/Allison XR700 is a very reliable ignition substitute for the original Opus system, and our PreHE's have that system on them. That system is working just fine, it runs, just not on the fuel in the tank.

If the rodents have made a meal of some wires you have found, then i am sure there may/will be others that they have dined on somewhere.

The MAF sensor unit on the RH side of the radiator support panel converts vac signal, from the hose attached, to an electrical signal for the 3CU for fueling purposes, and they do cause grief now with simple old age.

Again, the fact it runs on externally supplied "go juice" still points to loss of injector signal, and that trigger board we discussed in an earlier post is the prime culprit in all my dealings with the PreHE non runners. The injector amp, that big alloy box thing on the rad panel, is talked about at times, but I have never seen a bad one.

Still, the wiring is very suspect now that rodents have been in there, and old age is definately a factor also.