I suspect the fuel pump check valve on my 95XJ6 is not doing it's job. Sometimes when turning on the switch an instantly starting the engine it will stumble and sometimes die. A second attempt will get a good start and good idle. If I turn on the switch and let it sit for about fifteen seconds I get a good start and idle every time. I suspect the check valve is not doing it's job maintaning fuel pressure at the injectors. Is the logic correct? And if so is there a thread for replacing it or can someone give me some tips on a fix?

Thanks guys.

EZdriver 95XJ6

 

I reckon the "check valve" is in the pump itself?, which is inside the fuel tank.

The idle control valve may be having a moment and not keeping track of idle speed.

The fuel filter may also need replacing.

I read constantly on here of idle issues with the EGR system being the culprit. We dont have that system, so I have no fix idea for you.

The wait for 15 secs and then OK is an odd one, and just may be a coinsidence.

The fuel pressure regulator at the front of the fuel rail may be getting tired by now??.

 

The fuel filter was just changed. So no problem there.

It just seems that fuel is not getting to the injectors quick enough when starting. I know on other fuel systems there is a check valve in the supply line to maintain fuel at the injectors when the engine is not running. Turning on the key and waiting should allow the fuel pump to replenish the fuel pressure resulting in a good start which it seems to do. Regardless the idle is good once the engine is started and stabilized.

Now, where is the fuel check vave? Probably on the fuel pump which is in the tank ugh!

EZDriver

 

OK, now I see it a tad clearer haha.

The system in these cars is Nippon Denso, you may already know that, and when the ignition is turned on, the fuel pump runs for "about 1.5 seconds", AND, the system fires all 6 injectors, just to give the thing a squirt.

Thinking some more, sipping Merlot actually, the idle control unit may be sticking, and that 15 second wait gives it time to get where it needs to be, and that would explain the idle being OK when you take that time. I have never had that valve out, but others here, in your part of the globe, have had it out and cleaned it of some serious crud??.

The fuel pumps do get lazy after time, and I have had a few on the other Jags just do legs up at about the 100k miles area.

My X300 got noisy, at 180000kms, so I swapped it out. That is NOT a nice job on any day.

I did NOT use a Jaguar pump (Nippon Denso remember), as I found a generic Nippon pump here that fitted exactly and is common on Toyota Landcruiser etc down here. I did post that on this section a little time back, and it "might" be in the FAQ, or it will be in the archives. It gave part numbers that should be usable in any part of the world.

 

Turning the ignition on without cranking will give the fuel pump an opportunity to prime the rail before cranking. This will improve the starting if either the check valve or pressure regulator are leaking. The fuel injectors do not operate until the engine starts to rotate during cranking.