Hi Everyone,

I have a new "sound" that I need help identifying.

First, I just joined the ranks of the employed (3 1/2 yrs out) and started a new job on Thursday and they have me working six days a week for the next month, so time is precious, thus your help is greatly needed to minimize trouble shooting time.

The "sound". When I've started the vehicle for the past few days, it doesn't always continue to run after I release the key, it stumbles a little bit, cuts out and I probably need to remove the throttle body and do a good cleaning.

When it cuts out I hear a "gurgling" sound from behind the rear seat, so I'm assuming air is being induced into the fuel tank. I've never heard this before all of the years I've owned the car, sixteen years.

My thought right now is I have a vacuum leak affiliated with the emission control system after the fuel rail, another words the charcoal canister or the fittings affiliated with it.

When I crank the engine again the second time, it catches and runs and there is no issue with it running thereafter, mpg is good and it's responsive to adjustments to the throttle, no rough idle.

So does anyone have a better idea of where to start looking, time is precious ..... and seven days apart when it does come.

Look forward to hearing some solid ideas.

 

Rob,

First of all, congratulations on your new job! I know what extended unemployment or under-employment is like, and I'm thankful on your behalf.

Regarding your gurgling noise, your instinct about the fuel tank venting system sounds plausible. Given the number of accounts of collapsed fuel tanks, you may want to have a peek to be sure that isn't happening to yours (I know you are very familiar with your fuel tank!).

I haven't had the problem on our '93, so I'm no expert, but I seem to recall that the collapsed tanks are blamed on problems with the emissions control and tank venting system, especially the "Rochester Valve," which Jaguar calls the "Pressure Control Valve," Part 5 in the diagram at the link below:

Fuel Pipes - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK


I did a few quick searches of the Jag-Lovers archives for "fuel tank gurgling," "rochester valve," and "fuel tank collapse" and didn't see anything exactly like your symptoms, but at the post at the link below, Bryan gives a very basic explanation of the venting system:

JagFORUM Logon


Regarding the carbon canister and purge valve, I'm not sure which of the following parts diagrams applies to your car. The diagram at the second link shows two purge valves that Bryan mentions:

Carbon Canister-Up To (V)629361 - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK

Carbon Canister Purge Control - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK

Carbon Canister Bypass System - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK


There is also a Pressure reducing valve in the system, Part 6 in both of the diagrams below:

Fuel Tank-Up To (V)629285 - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK

Fuel Vapour System - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK


Another line of thinking might be related to the fuel pressure regulator, which is supposed to maintain pressure in the fuel rail (in conjunction with the check valve connected to the outlet of the fuel pump). When the FPR fails, it allows pressure to dissipate down the fuel return line to the tank. At startup, the fuel pump must now repressurize the entire fuel line to the rail, which often requires excessive cranking of the engine to accomplish.

One failure mode of the FPR is a leak or rupture in its diaphragm. Sometimes you can confirm this by removing the vacuum line from the FPR and checking for the presence of fuel at the vacuum fitting (you may need to crank the engine to be sure). I don't know if a failed diaphragm could allow air into the fuel system unless the vacuum hose was also leaking ... just thinking out loud about the possibility of air bubbles causing the gurgling you are hearing in the fuel tank.

Those are the things I can think to check - fuel tank for any signs of collapse, Rochester Valve and maybe the integrity of the hoses in the carbon canister system, and the FPR.

Wish I could think of more possibilities - hopefully someone else will know exactly what is going on.

Cheers,

Don

 

Don,

Thanks for the input, FPR sounds like a good and easy start point, examining the canister and components will have to wait for next Sunday. The tank is fine, no signs of collapse.

The pressure reducing valve is a pain to get to, IIRC that will include unfastening the tank and fuel filler latch box assembly in order to swing the tank out enough to even reach it......what joy....