Fuel delivery issue i think

Okay I am working on a stalling or heat soak issue, so i let the car run for awhile about 15 minutes or so and turn the car off and it will not restart so i checked spark and there is spark and i checked the amperage draw to the pump while cranking and it was about 7amps, so i am thinking about replacing the pump and the fuel regulator and i know the model number for the pump is LU-73351 but all i found is

and i am not sure if it is correct.

as for the fuel regulator i know it is JA-EBC2606 but i am not sure if i am looking at the right one

Are your working on a Series III 4.2 XJ6?


Series II 4.2L EFI is what I am working on

The fuel pump is alright. Don‘t buy one unless you have missing at full throttle. 80W could be a bit high (it isn’t according to google) but listen at the pressure regulator: do you hear a noise shortly after the pump starts running? (Test by cranking with the transmission in gear)

I’ll have to check that

What is the fuel pressure suppose to be at anyways?

I have read that fuel pump outlet pressure can be around 100 PSI but I have never tested it directly. I have hooked up fuel pressure gauges to our four Jaguars with Electronic Fuel Injection and recorded fuel rail pressures, as regulated by a properly working fuel pressure regulator, of about 36 PSI with the engine running, and about 40 PSI with the engine not running but fuel rail pressurized by putting the transmission shifter into Reverse or Drive and turning the key to Start.

Once running the fuel pressures stayed about 36 PSI in idle while parked unless I had some kind of blockage upstream or a failing fuel pump.

I hooked up the fuel pressure gauge between the fuel rail and the Cold Start Injector (CSI) in my Series III XJ6s using a “T” fitting so as not to disable the CSI. Sometimes I put about 3 feet of fuel injector hose from the “T” to the fuel pressure gauge and taped the fuel pressure gauge to the front windshield so that I could observe fuel pressure while driving. I did this when engine problems arose after some driving and I wanted to see if they were fuel delivery or ignition issues. While driving and accelerating up hills the fuel pressure rose to about 39-40 PSI in the cars that I tested that way.


What noise am I looking for or should I not hear a noise at all

You want to hear the regulator opening a little to bleed off excess fuel to the tank. It’s a noise I don’t have the word for… hissing, maybe. About the same as watching the return flow to the tank.
I’m not sure where the hot start issue comes from. What is your hot idle, and what could possibly change in the system given that you don’t have a hot start switch on the fuel rail (as all pre-82s)… not sure.

I could check the hot start temp sensor, but I do know the car shut off while drive and didn’t even studder or hassetate and I had to wait about 2 hours then it started perfectly fine

Ignition coil failure often manifests itself that way.

It’s also a common failure mode of the ignition module with the Lucas CEI ignition. However, I think your car has the OPUS ignition. I have no experience with that system


I am thinking the coil may be failing under a load even thou there is spark but I didn’t test a spark under load, I am gonna check the fuel pressure right after the fuel regulator but there is no room to do it after the regulator so that’s gonna be fun, when I was letting the car idle for a long time I could hear like a bubbling sound like fuel returning or air forming. I’ll take some pictures and always ask questions cuz this is really stumping me so thanks everyone

Spec fuel pressure is 36,25 psi - +/-0,75 psi, to be exact. Usually measured at the CSI rail tap-off. ‘Raw’ pump pressure is measured at the inlet hose - and is 100+ psi with a new pump.

If ‘raw’ fuel pressure is below 40 psi, the pumps is very worn, and engine is unlikely to run. Anything in between indicates the amount of pump wear…

Rail (regulated) pressure varies by manifold vacuum - generally to maintain a constant pressure difference between fuel rail and manifold. A diaphragm on the fuel pressure regulator acts, by vacuum, on a spring - bleeding off fuel to the return lines to regulate pressure.

The diaphragm sometimes fails, and if fuel leaks out of the vacuum spigot on the regulator - the regulator must be changed…

xj6 85 Sov Europe (UK/NZ)

Couldn’t you have said that earlier? Look into the ignition. If it just dies it is definitely not a fuel pressure problem. The noise you described sounds about right, assume for now that your pump is good and the pressure regulator works. If the diaphragm failed it would run very fat and smoke and die, which is not the case either. I don’t know any electronic ignition besides the CEI, maybe you can take pictures.

When I heard this I was my ear was near the pump, but i will still check to hear if i hear something like that at the regulator

The pump could be cavitating if the in tank pickup is blocked. After a while the debris may fall down and the strainer lets fuel pass again. Change tanks and if nothing happens look at ignition

I’ve not tested this idea, but it seems logical.
with the car running, (?). open the lid of the selected tank, or both. see if fuel is being returned… And doe it match the selection???

Use a spare spark plug connected to any plug lead - and crank…

As Doug says; engine suddenly quitting is usually ignition - fuel problems is sort of prolonged…

As an aside - with any engine misbehaviour; instantly switch tanks while watching the tacho. If tacho drops to ‘0’ with the engine still turning; ignition is lost…

xj6 85 Sov Europe (UK/NZ)

so i tested it again in the driveway, so first i put the car in Drive and tried to start it and then took a reading at the pump and it was 0.57ish amps, then i hooked up a fuel pressure gauge to the fuel rail, then i started the car in Park and it started fine. i also heard the sound of the regulator pee-ing back into the tank. so then i let it get to operating temp and turned it off and then back on again and it started just fine then i waited for about 2 minutes after that and then turned it off and back on again and it lost all fuel pressure (i watched the gauge go to Zero) so i took a reading at the pump and it was at 7-10 amps and it was no longer humming or buzzing just dead silent. the fuel pressure when it was working was stabilized at about 28psi

Beats me. I don‘t get it.
The fuel pump runs on 6w of power at idle?
Maybe a new one will do. All pumps that work for bosch FI systems work but there are quality differences. Huge quality differences.