250SX gas cap won't vent

[JThias]

After 30+ years of having a leaking gas cap, I finally decided to order a new gasket for the cap and, voila!, no more leaking. But as you can see, those three decades of doing wheelies and having gas splashing out of the cap onto the tank took its toll on the paint.

So with the new gasket and no more leaking, I've discovered that the vent feature on the cap does not work. After a few minutes of running, the engine wants to stall out, and simply loosening the cap for a moment gets it running again. I know the ultimate solution would be to just buy a new Clarke tank, but it's not in the budget right now. I'm guessing there isn't a fix for this either, as the on/off lever on the cap doesn't seem to be removable for repair.

Has anyone else had this issue, and if so, what was your fix? I've been thinking about drilling a small hole through the top of the cap that would be large enough to allow air in, but not allow gas to leak out. Or, maybe drill a larger hole and install a breather tube?

Go easy on me!

[Jd110]

Take the seal back off. Put the cap in apple cider vinegar for a couple days. Blow it out with an air compressor real good(in a rag). There are two holes on the side. Keep doing that until it vents again.

[JThias]

Take the seal back off. Put the cap in apple cider vinegar for a couple days. Blow it out with an air compressor real good(in a rag). There are two holes on the side. Keep doing that until it vents again.

Great, thanks. I actually filled the tank with vinegar for several days to eat out all the rust and it did a great job. Looked as good as new inside. I'll give it a try with the cap as well.

[Jd110]

I’ve done that, also. Remember, that process strips the coating off, as well. I always keep mine inside where it won’t ever condensate. 10 years later it’s clean as a whistle
Also, I spray cleaner inside the cap and blow it out to see if it comes out the same color ; then your getting somewhere. Last I lube it up inside the cap and keep it lubed.

[JThias]

Thanks for the suggestions, guys. After soaking, blowing, tapping, kicking, swearing, and a few other things I can't mention, I gave up on trying to get it to vent. I had to accept the fact that the mechanism inside is seized closed for good. So I bought a $5 breather tube from my local Honda dealership and just drilled a hole in the cap. Works perfectly now.

[Jd110]

Dang it anyway….they are very simple to open. Look how I lifted the low spots half way around to separate the 2. I have several extra. Most are really rusty, too. I’ll clean them up and they will work again.






The kind with two holes on the bottom are easier.




This one above is in good shape.

[Jd110]

Comparing the two pictures of your cap. It looks the same. Other than the tube

[JThias]

Dang it anyway….they are very simple to open. Look how I lifted the low spots half way around to separate the 2.

Well, NOW you tell me! Not a big deal. I've always kind of had breather-tube-envy with a lot of other 3 wheelers I've seen. Now I can blend in with them. haha

[Jd110]

Will you post a picture of the back of your cap to show what the vinegar actually did? Thanks

[JThias]

Will you post a picture of the back of your cap to show what the vinegar actually did? Thanks

I'll get a photo tomorrow. My trike is at work with the front end taken apart right now. Waiting on a new set of steering stem bearings so I can have her in tip top shape for Trikefest.

[Jd110]

You’ve had this trike over 30 yrs and you’re just NOW getting breather tube envy? What the he’ll has taken you so long? This is making more sense, now.
Well… have fun at the festival

[JThias]

Will you post a picture of the back of your cap to show what the vinegar actually did? Thanks

Here you go.

[Jd110]

Ok, looks good. Blowing air through the center hole would do no good. If you study the 2nd picture I posted, that’s your cap.
It has that plastic cup which has a one way valve at the bottom of it. You can blow air through the cup, but not back up it.
So when the switch is on I think it releases pressure so air can be drawn through the cup into the tank.
When switch is off it pushes down on that tiny plastic button and spring, sealing it off with the little oring.
Your fix looks like it should work fine. Let me know if you need another cap. I got an extra…

[JThias]

Ok, looks good. Blowing air through the center hole would do no good. If you study the 2nd picture I posted, that’s your cap.
It has that plastic cup which has a one way valve at the bottom of it. You can blow air through the cup, but not back up it.
So when the switch is on I think it releases pressure so air can be drawn through the cup into the tank.
When switch is off it pushes down on that tiny plastic button and spring, sealing it off with the little oring.
Your fix looks like it should work fine. Let me know if you need another cap. I got an extra…

Before I drilled the hole, I made a weak attempt to take the cap apart, but it wouldn't budge. Had I seen your pics before I gave up on that option, I definitely would have tried again. If I find myself needing a replacement cap someday, I'll definitely reach out to you. Thanks for your help!