XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

Rochester valve help.

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Old Dec 23, 2024 | 09:13 AM
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Default Rochester valve help.

Trying to resolve fuel odour in trunk/boot and an occasional whoosh when fuel filler is opened.

i assumed I needed a new Rochester valve so I ordered one.

upon reviewing parts diagrams, it doesn't look like Canadian cars had one of these, the evap system looks much simpler.

i opened up my inner fender to take a peak and found this(note I had already disconnected line to tank).



It appears that I have had the evap recall already, right? These parts don’t show on diagram and the white zip tie doesn't look original.

new rochester valve wont arrive until after the holidays. Other than simply swapping it out, is there anything else I should check? With the car off, i was very easily able to blow into the valve(into the “tank” line), I was able to suck air as well but it took considerably more effort.

any advice/tips appreciated.

 
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Old Dec 23, 2024 | 12:30 PM
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Rochester valves are NLA? Am I wrong?

I think you can simply remove it and forget about it. You will have to connect two different sized hoses. 1/4" and 3/8? Maybe 5/16?

I had nothing but trouble with the AC Delco aftermarket valve until it cost me a fuel tank. Now I have no valve and I'm happy.
 
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Old Dec 23, 2024 | 01:06 PM
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I ordered an aftermarket equivalent from Rockauto. It looks identical in the picture, we will see when it arrives.

WVE 2M1005

if I wanted to do away with it, would I just cap the vacuum line at source(i think its off the throttle body). Now that i look at this set up, seems overly complicated.
 
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Old Dec 23, 2024 | 08:02 PM
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Source is at the fuel tank. Do not cap it. You will end up buying a new tank.

Just pass it through to the charcoal canister. Theres also a way to tie an electric valve if you do some searching....
 
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Old Dec 23, 2024 | 08:10 PM
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What if I just bypassed the valves all together?

run the tank vent directly into the charcoal canister and the purge line directly to the intake?

ive see threads on wiring up switches, I am looking to simplify the setup.

What is the factory process? Does it purge only part of the time? Any drawbacks to having purge open all the time?
 
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Old Dec 24, 2024 | 02:22 AM
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To really simplify it, just disconnect the very thin hardline tube where it exits the chassis just in front of the LHS rear wheel, and let it vent to air. This is how all the UK cars came from the factory.
 
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Old Dec 24, 2024 | 03:30 AM
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Originally Posted by Greg in France
To really simplify it, just disconnect the very thin hardline tube where it exits the chassis just in front of the LHS rear wheel, and let it vent to air. This is how all the UK cars came from the factory.
really? So the UK cars just have the vent line ending up in the rear? If this is how the factory made them, I will just do away with all of it. Would this be illustrated in the parts diagrams? Im thinking I will just leave the thin hardline where it is in the LH front fender,
 

Last edited by nickr76; Dec 24, 2024 at 04:23 AM.
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Old Dec 24, 2024 | 05:37 AM
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Yes, really. This is a photo of the thin tube that runs behind the tank and then exits the chassis in front of the LHS wheel. It comes out of the evaporative cannister tubes up in the RHS buttress, via a Rochester valve on UK models (that will most likely not be there on your model as it had on in the front instead).
The tube is tiny and a free to air outlet will be fine.


 
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Old Dec 24, 2024 | 07:07 AM
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Perfect. Will remove the lot of it then.
 
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Old Dec 24, 2024 | 07:10 AM
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The original Rochester valve can usually be fixed with a simple cleaning. The valve just snaps apart and inside you will find a diaphram and spring. Soak and clean the plastic part (I forget which half) until you can blow through the tiny holes. Similar looking valves are different inside, but if you need a new diaphram it will be the same in other similar looking valves.
 
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Old Dec 24, 2024 | 07:12 AM
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Nick
You will find the end of the thin metal tube connected to the rubber tube that goes under the floor to that lashup at the front. Just remove the rubber tube from the end of the thin pipe. Then run the car for a few miles to ensure all good, then the entire lot downstream of the metal tube can be removed.
 
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Old Dec 25, 2024 | 12:42 PM
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I traced the line from where it exits the trunk.

there is a rubber coupler that connects to a single steel line that goes all the way to the front wheel well. Then there is another rubber coupler that connects to a shorter steel line that terminates where the charcoal canister is located.

i decided not to remove all the line and just have the vent terminate where it is. There are clips riveted to the floor all along the steel line, if i remove it I will have to deal with a bunch of holes.

same result as the factory UK set up just at the front of the car vs the rear.

 
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