Greetings fellow Jaguar enthusiasts! Although I have been a regular visitor of this site for many years, this is my first post .
I have read through a bulk of similar postings searching for a solution to my problem, however, I feel like I’m just chasing my tail at this point.
My Jag has been stored for the past 5 years with some brake issues that I didn’t have time to address . It was started regularly and has always fired up without hesitation. 6 months ago I finally got around to putting new calipers on the front, flushing the brake system and replacing the master cylinder. As soon as that was done , I went to go road test it and she would crank but not fire, even though the day before she fired up and ran perfect.
I have replaced the FPR, CPS, plugs Fuel pump and fuel filter. I have installed a pressure gauge in line about 10” from the fuel rail and I get about 7 lbs of pressure that drops immediately after turning off the ignition. I made an adapter to spray some Chemtool into the fuel rails to try and clean out my injectors. I had an assistant crank the car over as I sprayed into the fuel rail. She started right away and ran smooth as ever.
I really don’t look forward to pulling that tank again and spelunking around in the trunk. Perhaps I am missing something obvious to someone other than myself?
Thank you in advance !
J

 

If you remove the filter, and CAREFULLY use a tube to guide the fuel into a container, and then have someone crank the engine, it would show, for certain, if the pump was duff or not.

 

Hi Greg. Thanks for your reply. I am getting fuel to the rail, however it is only about 7lbs of pressure.

 

I undestand that; but if you have a bad new filter (it happens) and try the pump with the filter out of the way, you will see if it is really pumping like mad or not. If is is not, duff pump, if it is, something else!
Might be worth trying another FPR too, if the pump pumps OK.

 

J,

Is that 7lbs of pressure with the ignition on, or with the engine cranking?

The fuel pump will run for only 2 seconds when the ignition is turned on. It then cuts out. You need to measure the pressure with the engine cranking.

Cheers

Paul

 

Hi Cult Jag

I had the same problem on my own 1995 that turned out to be a 'duff' Fuel Pump Relay, that was only giving me a very weak stream of Petrol when Continuously Cranking

What you need is what you're going to see in this Video, which is a Full Bore Stream of Petrol Coming out like a Fire Hose while Continuously Cranking, as happened after I Changed the Fuel Pump Relay

(Side note to anyone trying this, do it outside and not in the Garage! and have a Fire Extinguisher handy in case the worst should happen)

Testing the Fuel Pump on my 1995 XJS (Don't try this at home!)

Turned out to be a 'Duff' Fuel Pump Relay!

 

Fuel pressure at the rail should be about 43psi, I believe. You shouldn't have any fuel pressure with the inertia switch triggered, but since you were fooling around with the brakes, you may have triggered it? Have you reset that?

 

Thanks for all the suggestions. I have been fighting a cold the past couple days so I haven’t had a chance to work on the jag.
Greg, i didn’t consider the new filter might be faulty. I will check that.
Hi Paul. That is on and cranking. It drops immediately after cranking or turning the ignition on. I have also clamped the return line behind the FRP to try and build back pressure. No change.
Hi OrangeBlossom. I didn’t consider the Fuel pump relay because I I did switch it out. I also hear it click and I can hear the pump running during cranking
Hey Vee. The inertia switch was my very first hunch as it has tripped for no apparent reason in the past. However, the switch is intact, untripped and as I mentioned above, the fuel pump is kicking on.
I attempted to monitor the live stream on my OBD monitor of the sensors. Although I’m not very adept on reading them, I did notice that in the short time I could monitor it, the MAF had zero data . Doesn’t the ECM monitor the MAF to deliver fuel?

 

Hi Cult-Jag

One more 'Trick to Try'

It could be the Fuel Pressure Regulator

If the Membrane inside of this has gone Porous, then Petrol could be going back to the Tank, which could then result in Low Fuel Pressure

 

Yes, it does!

If you aren't getting a reading, then that very well could be it.

A failed fuel regulator should show up in the little vacuum tube connected into it. Pull that off. If you smell gasoline, it's cooked and will need to be replaced. This isn't a part that commonly fails.

 

I checked the old one as well as the spare I put on . No fuel smell or residue in the vacuum line . I also had no change in pressure when I dead headed it.

 

I’m going out to work on her now. . I’m going to confirm that the MAF is not registering on my scanner and checking fuel pressure before the filter.
Are there any otter suggestions of what to look for when viewing the live data?

 

TPS % open at idle could be useful.

 

I think the TPS was reading 10.6 , if I’m not mistaken. I did however confirm that my MAF is kaput.
Does anyone know if/how you can test it with a multimeter?

 

Black with Yellow Stripe should have 12v to it when the engine is running.

Green/Pink should see 1.30V at 700rpm, 1.70V at 1500rpm, 2.3V at 3000rpm

Pink/Gray is the ground.

 

Thanks again everyone for the help. I had a biking accident that put me out for a couple weeks and was finally able to get back to the jag yesterday. :
I ended up replacing the MAF however, she still didn’t start. I unbolted and slid the tank back( despite the horror stories, it only takes me about 20 minutes to pull the fuel pump) and sure enough, the fuel line where it connects at the bottom of the tank was split!