Does anyone have pictures/detailed instructions on the best/easiest way to test the fuel pressure on the rail?
The easiest way is probably to find the fuel line going from the rail to the pressure regulator on āBā bank. Cut the rubber part of that line and insert a āTā fitting. Then plumb the rest of the way with whatever gauge set-up will work for you. Mine is a damped, permanently mounted gauge. Enlarge the photo and it might help.
1 Like
Correct me if Iām wrong. But since thereās a pressure regulator on each side then shouldnāt I test each side to be sure one side isnāt running lean and the other side normal?
Okay. I was about to take the fuel line off inside the engine bay but I can tell there is a lot lot of pressure built up on it. Best way to release this pressure without a gasoline piss rocket? And what would cause that much pressure buildup?
The fuel pump sends fuel to the first regulator on āAā bank. From there the fuel moves on to the fuel rail, which supplies ALL cylinders on your car. The pressure in the fuel rail is controlled by the second regulator over on āBā bank. So all cylinders see the same pressure controlled by the second FPR.
If you crack open a fitting and have a rag handy to absorb the fuel, you should be ok. Actually, that is a good sign- pressure in the rail! Without a gauge I think it would be hard to guess what pressure is actually in your fuel rail. You could wait overnight, or disconnect the pump or relay and crank the engine over to drop the pressure.
When removing the fuel pump relay, I noticed it makes a noise when shaken like something is rolling around inside of it. Iām going to replace the relay and do the pressure test before and after.
Pulling the relay caused the pump to stop working but it isnāt losing pressure when I turn the engine over. Thoughts?
The only thing I can come up with is that your injectors are not working, and thus not losing pressure in the rail.
Iāve always found a simple way to release fuel pressure is to just pull the inertia cut off switch by your left foot well. Give it a day or two and most fuel pressure is gone.
I just canāt imagine all 12 injectors stop working at once without some other reason
True enough. Here is something to think about, then. The ignition amplifier sends a signal to the ECU through a skinny coaxial cable that is a common source of trouble. The inner part of the coax shorts against the outer shield, which will kill all the injectors at the same time. Considering the problems you are having, it would be a good idea to look at the coaxial cable. Kirbert explains all this in the āBookā.
Do you know where I could buy a new set of these wires? I may as well replace them with something brand new.
It seems the fuel pump relay in my parts jaguar is missing, but after some research I found out that jaguar used the same relay in a couple different places. Any ideas where on the parts car I might find another one of these relays before I go buy one?
If you mean replacing the coaxial cable, you could go to Walmart, or an electrical/TV store and get a three foot piece of coax. Itās the same thing that cable TV uses, so there is nothing special about it. I hope you have read Kirby Palmās Book, because it is all in there. (the repair) ( and testing the integrity of the coax)
Canāt help you with the relay.
Do you have a picture of said coaxial cable? Keep in mind my jaguar does not have the ignition amplifier in death valley (Non OPUS ignition)
Where does it plug into? Left or right one?
No picture, unfortunatelyā¦ I have the same ignition/fuel injection as you do, and I repaired the coax on mine several years ago. The wire from the amp going to the ECU has a female connector. (P.155 in the Book) You should then look at P. 304, which describes the coax repair.
Iām not sure if youāve fixed this yet but it sounds a whole lot like a hot start on my 77ā.
I suffer from the perilous V1 fuel rails that will boil fuel back to the tank when the car is hot and the engine is shut off. Then, when restarting, It runs VERY lean and causes the same symptoms youāve described here. Itāll clear itself up in a few minutes as the fuel pump re-primes the rail, though itās not great for the car.
Have you tried turning the key to the Run position 6 or 8 times (not start) to prime the fuel rail with cool, fresh fuel? Now that the engine is cooled, I would do the same to re prime.
What was the OAT? Was the car in the sun?
Zack
1 Like
Look at the inside of the receptacle. How many pins or slots. Also at the connector, how many wires going in. Mot common are four or 5 pin. if four, any four pin relay will get it.
If it is a tin can relay, prize it open and check on the interior. lost something?? The rattle .
Be proactive contact David Boger at everyday XJ and get a good used one or possibly NOS!!
Just wanted to update everyone. Iāve been very busy the past few weeks and the car has been on the back burner. Told Iām going to order some new parts and look into the coax wire. I will update you all
I got a bit lost between the symptoms, and what changes have been done, sorry if I missed something, but what I understand is
- you car suddenly started misfiring and having back fire
- later on car fails to idle and dies
first one looks like electrics related, as thereās fuel to case the bangs, could be either failing sensor or coil, as suggested
second seems more fuel delivery, or bad timing (if thereās fuel smell at the back)
- ECU seems out of the problem, from your swap and from the pictures
- fuel pump seems ok as thereās pressure in the rail
may be a faulty fuel pressure regulator ?
no idea about the Lucas system, but could the distributor be stuck and give wrong timing ?
This sounds definiteley like a ignition issue to meā¦ Many years ago I had the same symptoms on a Rover V8. The engine was running smoth and after I parked the car the backfiring occured. I tried everything until i found out a marten bit small slots into the new ignition leads. The where invisible until I squeezed the cablesā¦ Installed a new set - job done 
Good Luck!
Sorry, me againā¦
Did you allready pulled the distributor out of the engine? Maybe there is something wrong with the dizzy driveā¦