Just got back from the gas station, and I can still only trickle a little gas in at a time... .

This is with both of the hoses to the CCV unhooked. I also put power to the CCV valve out of the car, and it snaps shut quickly repeatedly.

Bob, or anyone else -- What can you tell me about the EVAP tank flange? Any common faults there?? I DO have an extended warrantee, but it has a $200 deductible so I'm trying to fix it myself.

Thanks again for posting the earlier files, they made removal of the valve a snap!

 

There is a vent line that runs to the filler neck. Pull the cover over the fuel tank away and trace this vent line. Remove the line and ensure that the line and vent area in the filler neck is clear. If it has any clog in it, this spit back will occur.

 

oldmots,

Thanks for the suggestion. I have all the covers pulled off the tank. Are you referring to the metal line that taps into the top of the filler tube, or one of the rubber ones that attaches to the underside? The one that goes into the TOP of the filler neck appears to be hard piped to the tank, it curves and goes onto the top of the tank, but I can't see where it actually enters the tank. It is soldered or welded into the filler neck, so no way that I can see how you would check it for blockage.

Could I take a length of MIG weld wire and try to snake it to clear any blockage?

Is there some type of valve inside the tank that might go bad??

Anyone have any pictures from JTIS that might show a detail of this vent?

Seems like a pretty rare issue, I can't find anything relating to it when i search the forum. Please don't tell me I've found a new issue that nobody else has run across!!!

I really don't think it has anything to do with the pumps around here, we don't have the fancy gas nozzles in this area and even if I hold the nozzle so that it just enters the filler neck, it still comes rushing back out if I only barely squeeze the trigger.

HELP!!! Any of you techs ever seen this one before??

 

Have you tried a thin probe down the filler neck to see if something may be stuck down there? I finally gave up teaching the local gas jockey where to store the filler cap and fill up myself. In NJ we can't pump our own gas. These guys kept wanting to put the cap on top of the pump while filling. Something might have gotten picked up by the bottom of the cap then fell off into the filler neck. Just a thought. Had a price sticker come off a plate in the dish washer and clog it up. Jack

 

Pophen,

Thanks for the idea, that was my next step...

Will try a fish snake down the main filler neck first, but don't think I can make it into the vent tube to check it.

I was afraid of damaging any kind of valve that may be in the tank to prevent fumes from coming out...

Worth a shot I guess??

It's just surprising i'm the first to have this issue!!!

 

This is just my line of thought from doing research on this issue today. Take it with the obligatory grain of salt.

Quick relief - perhaps you can use a funnel to fill up your car. This way, pressure can escape from the fill neck while you are filling, but it won't cause the gas handle to shut off. Messy, but might keep you on the road if this issue becomes chronic.

========================

The issue is - the gas pump shuts off while adding fuel. So, why do gas pumps shut off? I have read three websites this morning that claim it is because gas covers the end of the fuel nozzle, here are two:

The Straight Dope: How does a gas pump know to shut itself off?

HowStuffWorks "How does a gas pump know when my tank is full?"

This means that gas is not properly flowing away from the gas pump handle while you are filling.

================================

Hypothesis #1: Gas is filling up your filler neck because of an obstruction in the neck.

There is a check valve at the bottom of the filler neck that is supposed to prevent gas from surging back at the operator:

2000 Jaguar Xj8 Problem Fuel Fill

The check valve in the tank sits in the filler neck, but JTIS says the filler pipe is integral to the tank and non adjustable, so that sounds like major work.

Also can't find much about this on the net, so, I am bypassing this as a hypothesis right now.

=================

Hypothesis #2: Pressure in the tank is preventing gas from flowing away from the gas filler neck.

I imagine if the tank was not properly vented, and the fuel was being vented back up the filler neck during filling, gas would not flow away from the neck properly, causing the gas pump handle to click off.

So, how do these cars vent the tank when gas is being added? It looks like your car has the On-board Fuel Vapor Recovery system introduced in 1999.

Standard Features - 1999 Jaguar XK8 Convertible - Yahoo! Autos

Found this document about it on jagforums - the issuing website is out of service, but a quick DNS lookup shows it used to belong to JaguarLandrover,53S/12/2, Lode Lane, Solihull, West Midlands, B92 8NW, UK:

http://www.google.com/url?sa=t&rct=j...v3e7Cnnj_C9TAg

Quote:

"The fuel filler pipe has a reduced diameter between the nozzle guide and the tank, providing a liquid seal when refueling and preventing the fuel vapor venting directly to atmosphere.

There is no breather tube fitted between the tank and the filler nozzle. To prevent spit back when refueling, a check valve is fitted at the lower end of the filler pipe inside the tank.

During refueling, the tank is vented via the fuel level vent valve, large bore vapor pipes and the charcoal canisters. The fuel level vent valve incorporates a float valve which is closed by the rising fuel level, creating a back pressure and causing the fuel delivery to stop.

In the closed position, the fuel level vent valve also sets the fuel level. With the fuel level vent valve closed (tank full), any increase in pressure or overfilling is relieved by a separate rollover protected grade vent valve.

The outlet from this valve feeds into the main fuel level vent valve vapor outlet pipe, by-passing the closed fuel level vent valve.

When the fuel level is below full, the fuel level vent valve opens to allow unrestricted venting via the canisters. A pressure relief valve is incorporated into the fuel level vent valve assembly and has an outlet pipe to the filler nozzle.

If a blockage or other restriction (eg, evaporative emission canister vent solenoid in the closed position) occurs in the vapor vent system, the pressure relief valve opens to allow venting to atmosphere via the filler nozzle guide and fuel filler cap."

====================

Analysis:

Looks like pressure is vented first by the vent valve to the canisters, and if the tank is full, then by the grade valve pushing out through the vent valve tubing, and in case of blockage, the pressure relieve valve built into the vent valve will push tank pressure back out the filler neck.

The vent valve has an associated solenoid that can close and block the ability of the valve to vent, but JTIS says this is just used by the computer (in conjunction with the tank pressure sensor next to these vent valves on the top of the tank) during testing, so it should be normally open.

This means that if your vent valve doesn't open for whatever reason (failed, or failed solenoid), and the grade valve can't vent pressure through the vent valve tubing, then the pressure will be pushed right back up the filler neck by the relief valve, which (in theory) would push the gas back against the filler handle, and cause the gas to shut off.

So - I would chase these things - vent valve solenoid, canisters, vent valve (and integral pressure valve), grade valve.

====================
Testing:

Personally - I am suspecting the vent valve solenoid or canisters, or associated piping. These items are common to the vent and grade valves. It seems more unlikely that both vent and grade valve will have failed.

First - check for codes. I read that you did this earlier, but emissions codes will prevent the ECU from purging the canisters.

Then, disconnect the line that connects the vent valve to the vent valve solenoid. When you fill up the tank using the funnel, does pressure come out of the vent hose, or does it come out of the filler neck?

If pressure comes out of the hose, try leaving the hose unattached and filling normally. Of course, at this point, you will be venting raw gasoline vapor around you and your car while you are fueling, but you will know it was a blockage in the vent line - solenoid, kink, bad canister, something like that.

If the pressure is coming out of the filler neck, even with the vent line open, then the relief valve is shunting pressure, so why is it doing that? JTIS says the canister vent solenoid is attached to the canisters, so I would test or replace that as a first step.

If replacing the solenoid does not fix it, then either the vent valve AND the grade valve are failing, or the canister is not taking pressure.

Can you detach the solenoid from the canister and fill the car? Does the solenoid vent pressure when you do this? If so, then the canister is broken. If not, then your vent and grade valves are kaput.

For some interesting reading on older Jag issues with this, go here:

http://www.jag-lovers.org/xjlovers/xjfaq/tankgasp.htm


====================

If you need it, this link shows how to remove the fuel tank, after making a special tool to do so:

https://www.jaguarforums.com/forum/x...p-video-63410/

I think the "Canister Control Valve" referenced in this thread is called the "Canister Purge Valve" by JTIS. Purging is the computer's way of taking vapors out of the canister and burning them in the engine.

Both JTIS and that PDF seem to show both vent valve and grade valve in the fuel vapor vent valve housing, right on top of the gas tank.

 

Here is an update, I was able to put gas in slowly using a small plunger. You can pour gas in slowly until it backs up, then keep funnel in 20 seconds, when gas slowly drains away from fuel fill port use plunger to push it down. After you do this there will be a gurgling/burping sound and you can then repeat the procedure. It took 20 min. to put 2.5 gallons in.

 

Addendum to update..you must put thumb over drain{a 1/2" dia stainless steel collar} located in body work in the fuel port area in order to plunge fuel. If you do not you can hear the air going in and out as you operate the plunger. that drain as well as the drain in the fuel port fitting both go directly in to the main fuel fill pipe. You can see this on the upper left in the trunk behind the trunk liner. It looks as tough I am going to the dealer on this.

 

Mcbeefsteak -- Thank you very much for the time and effort involved in researching this problem for us!! Especially when you are in the midst of your own issues. I hope your brake bolt problems are resolved soon. I am still trying to decipher all the information you provided. Where exactly is the solenoid for the vent valve, on top of the tank, or under the car??

Greg -- It sounds like we have exactly the same issue. Luckily, I have several other modes of transportation and can take my time to try and figure this out. I'd be very interested in hearing what the dealer has to say if and when you get to that point. Please let us all know in case other members are having a similar problem.

My latest update -- Last night I put a boroscope (camera) down the filler neck. Unfortunately, I couldn't get it to turn the corner leading into the tank. I WAS able to fish a piece of bailing wire past that point and could get 3-4" of dampness (fuel) on it, so I'm assuming that the valve (or whatever might be there) is OK. Either that, or there is a few inches of gas remaining in the filler neck above the valve.

 

going for another plunging session...do not smoke while doing this ha ha

 

Hey, no problem. People are helping me with my brakes, I am just passing it on.

Let me figure out how to copy diagrams into this thread and I will update.

Grew up in Tulsa, down the street from Steve's Sundries on Harvard. I remember the June 8th, 1974 tornado - we kids were hiding in the bathtub, I think I heard it go over our house. That was the one that ripped up the Braum's restaurant on Peoria and took it away, leaving the freezer with the employees hiding in it. I still get chills thinking about that freight train sound.

 

Nowadays, we have to worry about Tornadoes AND Earthquakes!!!!

We've had a few in the last couple of weeks, 5.6 was the biggest. I personally have not felt them, but some people felt it shaking their houses for 45 seconds or more!!!

Tulsa is just the right size of a town in my opinion, not big enough to have traffic issues, but still big enough to have plenty of things to do... Lived here since 1987 and grew up in Pryor, 45 minutes to the NE.

Thanks again for the help!! Looking forward to the diagrams if possible showing the solenoid location.

 

Yeah, now you can't hide inside OR outside!

Created an album: Jaguar Forums - Jaguar Enthusiasts Forum - mcbeefsteak's Album: XK emissions

Pics were shrunk on upload, I just open them, click enlarge, then push the CTL and + keys together to make my browser magnify.

The "fuel level vent valve" and "grade vent valve" are in the "fuel vapor vent valve housing" on top of the gas tank. If you watch Rev Sam's vid about taking out the gas tank, I bet you can see him remove this housing.

Here is how I think it is normally supposed to work:

(1) Gas goes in, and the fumes go out the vent valve, through a tube, through the "evaporative emission canister vent solenoid", and into the "evaporative emission canister". This solenoid is normally open.

(2) Tank gets full, vent valve closes. The grade valve then lets excess pressure out of the tank using the SAME PATH as the vent valve - tube, solenoid, canister.

(3) Then, the "pressure relief valve" (not pictured) built into the vent valve shunts pressure back up the filler neck to shut off the fuel flow.


JTIS says: "If a blockage or other restriction (eg, evaporative emission canister vent solenoid in the closed position) occurs in the vapor vent system, the pressure relief valve opens to allow venting to atmosphere via the filler nozzle guide and fuel filler cap."

To test, I would just pull the line free from the vent valve (if you can get to it), then fill. If you can't reach the vent, pull it off the solenoid.

If you still can't fill, then I would suspect the vent valve.

JTIS says: "The evaporative emission canisters are fixed to the underside of the vehicle either via semi-enclosed mounting brackets. Two fixing bolts are used at the front of the bracket and a single rear bolt supports the evaporative emission canister and the evaporative emission canister vent solenoid....The evaporative emission canister vent solenoid has a stub pipe with 'O' ring seal which is a simple push fit into the canister. A mounting bracket on the evaporative emission canister vent solenoid enables it to be secured to the underbody via the canister rear mounting bolt.A hose connects the evaporative emission canister vent solenoid to the bracket mounted adaptor into which the vent system air filter is screwed."

 

McBeefSteak -- thanks again for the uploaded figures. I can rule out the Evaporative Emmission Canister Vent Solenoid (under the car connected to the cannisters. I have removed it and tested it and it works fine. I also tried to put gas in it with it removed and had no luck.

Next I will try to unhook the lines running to the Fuel Level Vent Valve and / or the Grade Vent Valve (on top of the tank) and see if it helps the situation. IF I can get to it without removing the tank!!!

Thanks again for the help, we're narrowing it down a little bit at a time.

I have NOT looked at the Evaporative Emission Canister Purge Valve located under the hood, I may try that first since it's so much easier to get to...


Any fuses that I should check, and any idea which fuse box they might be in??

 

Not sure these are electrical, suspect they might be mechanical. Haven't seen any wiring to these valves in the diagrams, but have seen reference to a ball float.

JTIS says:

"The fuel level vent valve incorporates a float valve which is closed by the rising fuel level, creating a back pressure and causing the fuel delivery to stop. In the closed position, the fuel level vent valve also sets the fuel level.With the fuel level vent valve closed (tank full), any increase in pressure or overfilling is relieved by a separate rollover protected grade vent valve. The outlet from this valve feeds into the main fuel level vent valve vapor outlet pipe, bypassing the closed fuel level vent valve.When the fuel level is below full, the fuel level vent valve opens to allow unrestricted venting via the canisters."

So, at this point, I suspect you might have a failed vent valve, since it incorporates the grade valve as well. Good luck unhooking, let us know how it goes.

I think the purge valve just controls when the ECU releases vapor from the canister to the engine for burning.

JTIS says:

"Excess vapor formed in the fuel tank is absorbed into the evaporative emission canisters. While the engine is running, the fuel absorbed in the canisters is gradually purged back into the engine. The rate of purging is governed by the operating conditions of the engine and vapour concentration level. "

 

i had that with my 1999 XJ8 Vandenplas, it was the purge value
it was a nightmare trying to fill the tank.. 10 litres at a time if lucky

 

My Mechanic fixed this easily.....I was relieved

 

How so ?

 

Hello, When my mechanic saw the filler pipe and its other venting apparatus located in the trunk he was able to figure it out. He only had one hour in the job and $10 worth of gas.

 

sorry,buts thats not an answer,we want to know what he done