Hello,

My 92 XJ6 is having problems starting in the morning after sitting for a few days. Overnight is OK, but seems to be loosing fuel rail pressure, which could be the check valve.

Unless I'm mistaken, the fuel check valve is in the fuel pump (inside the fuel tank) in this year model.

Are there inline fuel check valves I can install?

Thanks.
JP.

 

I'm 99% sure you can Google "fuel line check valve" and find what you want.

But......

How long is is taking to start? A healthy fuel pump should repressurize the fuel rail within about 2-3 seconds. If you're cranking for longer than that I doubt that you have a check valve problem.

Just my 2-cents

Cheers
DD

 

What I meant to say was if you're cranking for more than 2-3 seconds I doubt that adding/replacing the check valve will do any good.

Cheers
DD

 

If I start it every morning, it only takes a second or two. But if I leave it sitting for 3 to 4 days, then it takes a 30 or more seconds of cranking, almost to the point of running the battery down.

I am not sure if it's the fuel pressure, at first I thought it may be a sensor but don't know what else but the fuel check valve would cause that behavior.

 

How long has it been since you have replaced your fuel filter?

There is a fuel non-return valve in the fuel line but a faulty one will usually cause the opposite problem...easy starts when cold but cranky starts when hot...

 

Where is that non return valve in the fuel line located? My white 90 sovereign fires up instantly when it is cooled down, or within 20 minutes of its first start. If it sits an hour though it will crank 6-14 seconds before it starts up.

 

On my '88 Cat the fuel non-return valve is located inline on the end of the external fuel pump....for the other models I'm guessing that the valve should be in the same location (off the end of the pump).

From memory the Haynes manual doesn't have any info on it. It took me over 6 months before I accidentally stumbled across the info and only 30 minutes to replace and now my Cat starts first time, every time with a 1/2 second crank!

 

"Why would a clogged filter cause the problem only when cold?".....

Think of what happens when you leave ice out in the sun! Try changing the filter and see if it improves your starting issues.... If the filter is clogged with "gunk" then the fuel can't flow properly.

Any "gunk" in your filter (and fuel system) will warm up as the fuel moves through it which will cause the fuel (and the gunk) to become thinner and therefore it will be less restrictive and move easier through your fuel system. When the "gunk" is cold it will be severely restricting the flow of fuel as the fuel (and pump) has to work harder, to get the fuel and the gunk warm enough to get it flowing through the system.

Any fluid needs to be able to run uninhibited so a new (unclogged) filter will greatly improve the flow both when it's cold and when the system warms up... simple fluid mechanics

 

mrtalk, your check valve is on your fuel pump, which is the suspension mounted type used on 1988-1990 models. Cars from 1991 on use in-tank fuel pumps. Jaguar never made that check valve available separately, but Volvo used an identical valve and does make it available. I don't know the part number, but it screws right onto the pump outlet.

That might be worth a try.

Cheers,