1985
Jaguar XJ6
Albuquerque NM

I have recently been having an issue with my jags fuel system. It starts just fine and gets moving but anytime I get up to about 2500 rpm's it starts to give out. Acting like it wants to die out. I let off the gas and motor runs fine. But as soon as I give it some gas it does the same thing. I replaced the fuel filter and pump located in the boot last summer. Could the filter need replacing again? This is my first jag and have only had it for a little over a year. I'm a novice when it comes to cars but am pretty good at doing the basics. Any advice would be much apreciated. A few people have told me to clean out the fuel lines but not exactly sure how. Thanks in advance for any help.

 

Two things come to mind; (I am assuming your car is a Series 3 XJ6 4.2 litre with the Lucas-Bosch fuel injection). From the symptoms you have described you are getting fuel starvation when you put some power demand onto the engine.

1. There is a pressure relief valve on the fuel rail to regulate the fuel pressure. If the seal on the spring-loaded valve has failed, there will not be enough fuel pressure to supply engine over the full power range.

2. There are gauze filters in the tank where the fuel is sucked up by te pump. These can get blocked with rust and crud over the years. Checking and cleaning these involves draining the fuel tanks, so be careful !!

 

Also check that your aircleaner is not plugged up, fuel starvation and air starvation act the same.

 

Ok I have a haynes manual and have been looking for the pressure relief valve in the book so I can locate it on the fuel rail and for the life of me I can't find it. What am I looking for?

 

Am i looking for the pressure regulator?

 

Sorry, yes, fuel pressure regulator. This does relieve fuel pump pressure by dumping fuel into the return pipe to the tank. I believe on later models there is also a connection to allow a pressure gauge to be attached to check fuel pressure.

 

ok I was driving myself crazy looking for a pressure relief valve. Lol I'm draining the tanks this week and hopefully changing the filters in the tanks. After looking at the pressure regulator it doesn't seem like there is a place to hook a pressure gauge to. If I can't what's another way to check it? I hope I'm not being too much of a bother. I can't find anyone around her with an older jag that hasn't put a chevy 350 in it.