Jaguar Repair: XKE S3 New Solid State Fuel Pump overheat, fuel starvation, vacuum lines

Question
In my 1974 XKE S3 V-12 the SU double fuel pump has been replaced with a new solid state double fuel pump.  Pump works fine at first when driving the car but when car is pushed at 65-75 mph, the engine begins to slow and signs of fuel starvation are apparent- gas pedal begins to "mush" and engine staggers, loses power and decelerates regardless of gas pedal position.  Lowering speed to 50 mph regains some power to the engine but even so the engine won't accelerate rightly. Car will limp along without stalling but won't accelerate properly.  I checked the fuel pump after driving and found the center portion too hot to touch-really hot! (some of the foam insulation had melted in fact.)  Since this is a new fuel pump and the engine is rebuilt with new carbs and such, I believe the problem lies with the pump.  It may be that the FP is so hot as to be boiling gas and vapor locking the fuel lines- but that is only my speculation.  I have gone over the vacuum lines and found one small one missing (not of consequence in this problem, I believe)with the others properly connected.  Fuel filter is not blocked.  Air filters and air stream are clear. No sign of gas problems- (I had an issue with another car whose tank had fuel additive residue in it which, when ethanol enhanced gas was introduced, came out of its solid, dried up state and turned the gas-additive mix into a gel the consistency of hair gel. Fuel line became blocked, carbs jammed, engine quit.  However, although I looked for it, I did not find that problem in this car.)

  Original FP wiring was simple; one wire in and another to ground.  The replacement FP uses two wires with no ground. Wires are white and black.  The FP mounting still contains the original green ground wire and what looks to be a diode or resistor on the mount. I have been unable to find a wiring diagram for the replacement FP or get any other connectivity info for it.

FYI, engine has approx 10 hours on it since overhaul and rebuild.

  Bottom line Qs are these:

 Since the FP is overheating, is the cause of the overheating due to improper wiring (lack of ground, non-connection of diode/resistor?)  

 Is the FP the cause of the fuel starvation at higher highway speeds? Or am I on the wrong path and the overheated FP is not the culprit, although obviously not working to spec?

  And thanks much for your time spent and expertise used to answer these Qs.

Answer
Hi Geoff,
Your diagnosis "may be" correct but you are doing a lot of assuming. When I worked in Jag dealerships we could not use "may be" this or that. When we suspected fuel supply as a fault we had to connect a "T" in the line feeding the carburetors. Then run a long hose out from under the hood (Bonnet) and place the fuel pressure gauge under a wiper arm so we could monitor fuel pressure under the conditions of failure. (Be sure to put clamps on all hose connections)

As for the new pump getting hot enough to melt anything more stable than chocolate, something is wrong there and you need to contact the seller or manufacture of the pump.

Your symptoms are that of a dozen different problems so testing is the only way to correct any problem. You may even have exhaust back pressure. I have found over the years many MGs, Triumphs and Jaguars with excessive back pressure. I tested many British cars and found that none could stand more than 1.5 PSI under load.
Howard