Looking to see if someone can clear this for me. I have been working ony friends 1984 XJ-S V12 which no obstante is in good shape, it has been neglected and worked on by people with absolute no knowledge on this cars. The car quit running and was sent to a mechanic who was not able to fix it, I am now updating all the wrong issues I come across, and I think the problem is the ECU, but I changed plugs, ignition cables, rotor, cap, serviced the inyectors, adjusted throttle and TPS, coax cable, temp sensor, etc, but I came across this following issue:


I changed the 1/2 curved hose from the surge tank and cheked for any issues with the filter, it was clean. I also changed the fuel pump which was noisy for a new one also changed the hose from the pump to the fuel filter... Nothing fixed the bubbles (cavitation?). Then I sterted working on the hoses before and after the right hand fuel pressure regulator looking for a damaged hose, no luck... The only way I finally got rid of the bubbles was to bypass the RH FPR...


My question is, I know this is not right but I don't understand how a faulty FPR could cause this issue, (by the way, the car has a "new" regulator and also tested the older one with no change, both FPR hold vacuum and hold pressure in the line from the pump) so, what might me the cause of this bubbles?
I will not be installing the RH FPR, I have read here the it's not needed, but makes me wonder why, while both FPR hold vacuum, they both produce this issue.
Any thoughts?
English is not my first language, so I hope I was clear...

Two more videos on the same issue:

 

Well done.

That RH FPR was a "pulse damper" as per the spiel from Jaguar cak in the day.

My GO TO on any HE that dares darken my door, is to remove that FPR, and then move on to whatever else is upsetting the thing.

The why and whatever, who really cares, it is a simple, well done and proven fix, beer time is wasting.

Read my stickies at the top, and ask if you want more PDF's.

You dont say where you are, might be a good idea to indert that in your Sig, as these beasts do vary a LOT from market to market.

 

Grant,
You are right, no need to know the cause, just move on, thanks so much for your reply.
I'm located in Mexico and the car is a USA model...
Will let you know for sure if I need any more help.
Best regards
Alfredo

 

Let us set aside the bubbles issue for a moment. ( Which I believe is not a problem, just an observation) Couple of questions: Does the engine run? If yes, please define what is the problem you are trying to correct?

Speedster-Michigan

 

The car does not runs, I have found many issues like wrong plugs and gap, throttle and TPS not adjusted properly, and many more. I know none of this are the cause for the car not running, but they have been addressed. I have checked continuity on the coax and temp sensor and so on.
The car hardly started and idled for about 30 seconds as long as the throttle was not opened, then it would die. I think the problem is the ECU, I have a known working 16 CU that will try once I finish addressing all the mentioned issues, but before reassembling the fuel rail with the new hoses and injectors serviced, I decided to see if I had a proper flow of fuel, I tested the pressure before and it was fine, but wanted to see the liters per second that the pump was delivering, this is when I noticed all the bubbles in the line. I know this was not the cause for the car not running, but I also think this can't be right.
I hope I could explain my self.

Cheers
Alfredo

 

First, always have a fire extinguisher close buy when trying to start an engine, I would try this. Get a can of spray starting fluid and two people. With someone in the car working the starter button or key, spray some starter fluid into the intake and if it starts keep spraying fluid to keep it running for 5 or 1o seconds. If it starts and keeps running on starter fluid you now know it's not the ECU.

Speedster

 

Or probably the ECU is not sending the proper signal to the injectors! This is my diagnose...