Rollover valve

Okay. Multi part question. I’m so tired of this not being able to fill up normal BS. From what I gather, my rollover fuel filler neck valve is closed. I cant fill up without constant pump shut off and I can only fill up the neck, let it drain and repeat. Has anyone successfully opened the balance without removing the tank or bed? Anyway to remove the valve or modify it permanently open?

 

Take the vent hose off the roll over valve and see if you can blow into the tank.
That would let you know if the valve is bad.
Looks like the valve is mad into the tank and not serviceable.

You could also have a restriction in the filler pipe.

 

I recently replaced my fuel tank and I can tell you that the check valve is removable because you need to swap it over to the new tank. That being said, your valve may be installed backwards allowing free flow out of the tank and not into it. Have you had any fuel maintenance done in the past? Previous owner maybe? You should be able to disconnect your fuel filler neck from the tank if you have tiny arms and can reach between the frame and bed. You may need to remove your drivers side wheel liner to make it easier to reach. The room is tight but that should work. If you have a stock tank, dropping the tank might be the easiest route for you to go since its a strap and a few bolts. I'm running the LRA tank and it'll be easier for me to slide the bed back than to drop the tank. Are you throwing any codes that might lead you to an issue with your charcoal canister or breather line?

-J

 

Oh yeah, I’ve got all kinds of fuel pressure/evap codes. All the typical Toyota fuel codes. It’s been getting worse and now I can’t put more than 1/2 gallon at a time to fill up. You can physically see the fuel back up

 

So to me it sounds like your issue may be something else that is related. There's a pressure test that you can run on your charcoal canister to see if it's bad but with the custom taco fsm site down, I can't link you that test. You'd have to manufacture a pressure gauge to check holding pressure though.

-J

 

And that would cause fuel to back up the filler neck? To be clear, I could care less about the lights or codes. The truck is so modified, I could care less. And I’ve had it pressure tested and smoke tested. Already replaced the cap and several valves. Canister tested “good” from what I can tell. I’m thinking rollover valve due to it just happening this last month after several long days at the dunes. Whoops and lots of high speed “prerunning” type driving...

 

It's difficult to say for certain however I would guess that the tank is trying to exchange air out through the filler neck instead of out the charcoal canister. With that being said, pull the roll-over check valve and make sure the flappers move but I wouldn't modify it so that it stays open as it's a safety related item designed to hold fuel in your tank in the event of a rollover. I wouldn't want you to put yourself or others at a risk of fire or explosion in the unlikely event of an accident. Please check the function of your charcoal canister to make sure that's working correctly since you mentioned that you burn down those dirt roads, my guess is that this is your problem or at least one of your tank filling issues.

-J

 

How can I check that myself? I had it smoke tested and the shop “said” it was good....

 

With the custom tacos factory service manuals down at the moment, you'll have to forgive me but check this video out at the 28 second mark. I'm guessing that is the issue with your canister. I'm guessing that it is stuck closed. This guy checks to see if the solenoid opens by jumping it to a battery and listening for a click. He also blows air into and out of the valve to check for continuity. His home-built smoke machine isn't necessary unless you suspect it's has a leak, in your case, I suspect it's clogged. Keep in mind that this is a Gen 1 3.4l Tacoma, so our charcoal canister is located above the fuel tank closest to the driveshaft so it's difficult to see and feel around up there but the components are similar.



Here's a link to a post on how to replace the charcoal canister.
https://www.tacomaworld.com/threads/how-to-replacing-the-charcoal-canister.387775/

Before you go this route, I would check the easiest bit first by pulling the filler line off of your tank and checking the roll-over valve to make sure it's installed correctly. Pull the liner out of your rear drivers fender and look toward the filler neck. Follow the fat hose down over the top of your frame and you may have enough room to squeeze in there to disconnect it. If my memory serves me correctly, it's a crush clamp that youll need some pliers to squeeze tension. Wiggle it off and finger out the valve. I don't believe the valve is screwed into the plastic nipple, it should just pop out. Clean it with some fuel or denatured alcohol, I wouldn't use any abrasives such as brake-kleen since it is a plastic part and it could deteriorate the component. The valve should hang freely open when you reinstall it. Hope this is helpful, please keep us posted.

-J

 

I’ll look into it. I really think the whoop sections and jumps are killing that valve. There’s tons of room under my truck, the bed is cut for spares and I have no inner fenders. Just fiberglass bed sides....