XJ6 & XJ12 Series I, II & III 1968-1992

Fuel return valves Series III XJ6/12

 
  #21  
Old 04-24-2019, 04:30 PM
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I did my homework on how to troubleshoot, jacked it up, removed wheel, found the sheet metal panel covering the fuel switch over valve (on the left side). Removed the two sheet metal screws. There is a bolt on the left side. (See photo) Loosened that but it feels like there is a nut on the other side. Now it just spins without coming out. Seems to be boxed behind it - can't feel a nut. Any ideas hot to get that cover off?

 
  #22  
Old 04-24-2019, 06:42 PM
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Try applying some pressure with a flat blade screw driver between the cover and the undercarriage to see if that would jam the nut on the backside. The threads could be stripped on the nut rather than the nut turning. If that fails you may have no other choice but to cut the head of the bolt off. Once the cover is off you will be able to see what is going on.
 
  #23  
Old 05-12-2019, 05:15 PM
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Originally Posted by Jose View Post
the swoossshh when you open either filler cap is a separate problem, i will answer that:

there is an inline check valve at the front inner fender behind the tire. This check valve is supposed to OPEN when vapor pressure exceeds a certain calibration, but it doesn't, causing a buildup of fuel vapors in the tanks which make the tanks expand and contract until they start leaking at the seams.

the vapors are supposed to go through this check valve on their way to the Charcoal Canister, and from the canister into the engine compartment where there is an electronic Purge Valve that opens and allows these vapors to be burned by the engine. That is the way it is supposed to work but the Check Valve gets in the way.

The solution to eliminate the buildup of vapors at the tanks:

Remove the Check valve and push a drill bit on one side and pull it the other side. This will break the inner membrane that prevents vapors from moving through it. Reinstall the check valve and no more swwoooosssshhh.

This solution has been around since the late 1980s. There are no negative effects.
Jose,

I had the swoosh for the first time yesterday. It was a warm day here in the Seattle area (82 degrees) and when I got home and pulled into the garage, I noticed the fuel pump was noisier than normal. I was using the right tank. When I got out of the car, I could hear a gurgling noise coming from the left gas cap. I opened up the cap and “swoosh!” came from the tank.

So today I did what you suggested with the valve. I drove the car today and no “swoosh. However, it is ten degrees cooler today but I’m pretty confident my problem is solved.

Thank you, Jose!

Danny
 
  #24  
Old 05-12-2019, 05:56 PM
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Danny, that is good news.
chances are you will not have any more pressure buildup regardless of ambient temps, it's that check valve that causes the problem It is a GM check valve,
 
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  #25  
Old 05-18-2019, 05:35 PM
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It was warm again today and my swoosh returned from the left tank even though I drilled through the valve. I was driving on the left tank. When the pressure builds, the fuel pump gets noisy. And if I have the windows down and I back up I can smell fuel.

Should I disconnect the hoses to the charcoal canister? I read that should fix the problem too. Or buy a new valve?
 
  #26  
Old 05-18-2019, 06:14 PM
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try just removing the valve and leaving the system open a few days.

both tanks send the vapors thru the same line so it doesn't make sense to me. In my '84, there is no vapor buildup at all and the system is intact except for the defeated check valve.
 
  #27  
Old 05-19-2019, 01:15 PM
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Here’s a pic of my canister and valves. I think there are two. We drilled through the one marked #2. Should I drill through #1? Which hose should I remove? I think the one after #2 before it goes to the engine. Or both?
 
  #28  
Old 05-19-2019, 02:01 PM
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Confusion!!!!

1. This system uses a fuel return system. In the engine bay, the fuel pressure regulator
returns fuel to the tank. Which ever is selected gets the return,

2. The tank vent system is different. It is a closed system in modern cars, including these. The tanks vent to the engine. Danny's picture depicts the Cannister in that line.
It terminates at the engine via the purge valve. In essence, the tanks vent to the engine.
Indeed the cannister is a GM product. I have the one from my donor Cadillac under my bench. It looks very much like the one Jaguar installed in my car in 83!! The Cadillac was of 94 vintage....

Return and vent are different!

Carl
 
  #29  
Old 05-19-2019, 02:42 PM
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Carl,

I think I understand you.

So to solve my non-venting problem, should I remove the line in #2 between the valve and the canister? The valve and line in #1 should be left alone?

Danny
 
  #30  
Old 05-19-2019, 04:04 PM
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I am more confused now, the check valve I am referring to is not at the charcoal canister, but way before you reach the canister.

it is mounted above the shock absorber top, or near.

Yes, there are check valves at the charcoal canister itself, but those are not the cause of the buildup of fuel vapor gases.

the one that needs removal or drilling thru is the one in the picture below. It is mounted to the inner wheel well.

 
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  #31  
Old 05-19-2019, 07:47 PM
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Jose,

I thought you meant the one I took a picture of. I looked and don’t see this valve near the shock. Maybe I’ll have to take the wheel off to get to it. Thank you for the help! I’ll post back after it’s done.

Danny
 

Last edited by XJDanny; 05-20-2019 at 08:13 AM.
  #32  
Old 05-21-2019, 09:03 PM
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We took the wheel off today and there are no more valves. There isn’t a valve before the charcoal canister, at least in the wheel well. We drilled a hole in the #1 valve in my photo. We had already done the valve #2 in my photo. Could my car have a valve somewhere else?
 
  #33  
Old 05-22-2019, 06:13 AM
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remind me again, what year is your XJ ? Build date is on driver's door sticker.
 
  #34  
Old 05-22-2019, 08:55 AM
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It’s a MY ‘87 and the build date is 1/87.
 
  #35  
Old 05-22-2019, 01:52 PM
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For what it is worth, my 87 was built in 7/86. I had tank pressurization problems, I drilled out the valve in the back (I didn't even see the one in the front) as suggested by Jose and that fixed the problem. Maybe you have a blocked line.
 
  #36  
Old 05-22-2019, 02:19 PM
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Thank you. When you say you drilled the valve in the back, which one do you mean? Was it one of the ones like in my photo?
 
  #37  
Old 05-22-2019, 04:15 PM
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Yes, the one you labeled #1.
 
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  #38  
Old 05-22-2019, 05:30 PM
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remove number 1 and compare with the photo I posted. Maybe the 1987 has it in a different position?
 
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  #39  
Old 05-22-2019, 09:46 PM
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Originally Posted by Yellow series3 View Post
Yes, the one you labeled #1.
I had drilled the other one and it didn’t solve the problem. I just drilled the one you did. It’s going to be warm this weekend. I’ll drive it and see if that solves the problem.
 
  #40  
Old 05-22-2019, 09:54 PM
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Originally Posted by Jose View Post
remove number 1 and compare with the photo I posted. Maybe the 1987 has it in a different position?
Just by looking at it, the one in your picture looks like my #2 in my photo, which is the first one I drilled. If after drilling the other one doesn’t solve the problem, I’ll remove them and compare them to your pic.

I’m hopeful drilling the same one as Yellow Series 3 did will solve this issue. I sure hope it does, I’ve had so many fuel system issues on this car and I’m so tired of it. I’ve cleaned both tanks, installed fuel filters on either side of the changeover valve, replaced the changeover valve, replaced the fuel pump, and replaced both return valves. And now I have this vapor issue, which just cropped up. Sheesh!
 

Last edited by XJDanny; 05-22-2019 at 11:40 PM.

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