Venting....
 

OK,
did some searching today after some reading on gas caps for the ramp truck and the very strong gas smell inside the cab. I found a thread from a while back and didn't save it. It was about modifing the vented gas cap to work better by cutting the spring off. So after reading the thread I went and got my old cap and started to take it a part.
Turn it over and take a small screw driver to the 2 small tangs that hold the ring in place. Bend the rings out straight. Pull the ring out. The black plastic part will come out also. The cap will look like the last picture. You have a rubber seal that moves around and if you look close there are two small weep holes also.

Next.:chevy:

Re: Venting....
 

OK you have it broke a part.
Next flip the black plastic over and you will see a plastic ring with slots in it and looks to have a rubber seal under it. Take the small screw driver and pop off the round plastic ring in the first picture. Then the rubber seal and plunger will fall off. The spring is under it. I cut mine in half. Then just clean it good and reinstall as you took it a part. This should let the tank vent at a reduce pressure and keep the tank vented. At least that's what the other post stated. I haven't been able to find it again though. All the pictures where also gone in the thread because of the host site.
The instructions where there but no pictures.


NEXT::chevy:

Re: Venting....
 

So I had bought a new cap from o-R auto parts a few weeks ago but I took it back this afternoon after modifing the old one. I was going to do it to the new one but couldn't figure out how to get it a part. The ring doesn't have the two small tangs on it holding it in. I didn't want to tear up the new one so I just took it back.

I'm going to try and find a cap like what NAPA has and see if I can modify it.

If this doesn't work I have a new sending unit on order and will install it with enough hose to run up into the passenger side cab wall and out through the floor to the frame. I may run it to a canister are just run it to the back of the truck.:chevy:

Re: Venting....
 

Tamper proof. Don't you just hate those? ;)

Re: Venting....
 

:lol::lol::lol::lol:

Yea I plan on going to NAPA Monday and seeing if I can get a good one.

Re: Venting....
 

you could try this but I am not so sure about the site. They list all the correct stuff about it...

https://www.cjponyparts.com/vented-g...-1971/p/GC111/

Re: Venting....
 

I wished they show the inside of it. I'll see if NAPA can get me the one they show on their website. If not I may try this one.:chevy:

Re: Venting....
 

How is this going to fix the leak inside the cab? If you are getting fumes in the cab you have a leak somewhere.

Re: Venting....
 

I have been looking for signs of leakage and haven't found any. The tank is dry no sign of a leak. That's what I don't under stand about this. The tank never had problems before I had it cleaned. The smell before was minimum at worst. Now when it's full it will knock you down when you open the door after sitting a day. The only thing changed is the old sending unit had the hard line all the way out under the cab floor, now it's fuel injection rubber hose line. New seal also. I suspect the seal on the sending unit, when I first installed it I had a gas gauge problem and I tapped the lock ring back a bit and the gauge started working so I left it. I may try tapping it back fully down again. But it's not loose by no means just not fully seated though.
There are several threads on this.:chevy:

http://67-72chevytrucks.com/vboard/s...d.php?t=666215

http://67-72chevytrucks.com/vboard/s...d.php?t=390464

http://67-72chevytrucks.com/vboard/s...d.php?t=624413

http://67-72chevytrucks.com/vboard/s...d.php?t=624413

Re: Venting....
 

hmm, perhaps when it is empty again you can figure out a way to pump air into the tank from a compressor after closing off the fuel out line? Put some soapy water around the sending unit to see if you get air bubbles?

That is totally off the top of my head and could be a real stupid idea....

Re: Venting....
 

As of right now. I went out to the truck and open the door. The smell was there but not near as bad, but the tank is half full.

I decided to lock the sending unit lock ring down all the way. I also took the hose clamps off and rearranged them so they are 90* apart on the hose fittings. I also moved them in closer to the fitting just for good measure, that second hose clamp was close to the edge of the fitting.
I guess I will fill it up and see if it helped. :chevy:

Re: Venting....
 

Just for FYI, and I can't tell in the picture, but does the rubber hose you are using have any green lettering on it? I'm understanding fuel hose with green lettering is known as barricade hose which is to be used with modern ethanol fuel. I've read numerous posts online that ethanol vapors penetrate the old style fuel hose.

Re: Venting....
 

Good question. I can't say right off but I will look tomorrow and see. I do know it's rated for modern fuel injection pressure.:chevy:

Re: Venting....
 

Add a 2nd clamp to the steel line coming out the floor. With the screw drive 180* from the other clamp.
It might be the photo, but that pass side lower corner of tank looks damp.


https://67-72chevytrucks.com/vboard/...1&d=1610913146

Re: Venting....
 

If it were me, I would bend a new steel line all the way up to the sender to all I have to use is a rubber hose about 2-3'' in length instead of the 16-18'' that is showing there.

Re: Venting....
 

There are two clamps on both connections on it 180* out now. The floor is dry.


I have thought about that also just haven't taken the time to do it.

Re: Venting....
 

Look at the corner of that tank. floor might be dry, but it looks damp. fuel evaporates , So a tiny leak isn't going to wet the floor.
Again it might be the photo, but that flange in that corner looks damp.

Re: Venting....
 

I'll go look in a bit, I think it's Shadowing though. I had the afternoon sun shinning on me when I took those.:chevy:

Re: Venting....
 

Just went out and looked. Not much smell when I opened the door but it only has half a tank of gas.

I was wrong on the rubber fuel line though. It's not fuel injection line.

But it doesn't have the green writing either. No signs of leaks any where I can see.:chevy:

silverstreak,
This maybe the answer!:chevy:

Re: Venting....
 

I have been to Auto zone, Advance auto and Napa nobody has the cap. I'll just keep mine as is and see how it ends up doing since I modified it.
The new sending unit will be here sometime this week if the dang mail people don't loose it. Once I have that I can vent the tank myself and not worry about it.:chevy:

Re: Venting....
 

Update. Tank sending unit has been changed to a vent sending unit. Still has the gas smell but not as bad when full but it's still there. I ran the fuel line vent over to the passenger side and up into the cab wall like a 71/72 model. It's no where near as bad as it was but it's not completely gone either.
Anybody got any suggestions.

It never smelled before I had the tank cleaned out.:chevy:

Re: Venting....
 

gee, wished I had a idea. but perhaps you just have residual? Or perhaps since you are not venting into a canister, maybe its is getting back into the truck from your vent hose? Its not like these trucks are perfectly sealed from the outside. The vapor coming from the hose is pretty intense (concentrated).

Before I replaced my canister the smell was really bad (when opened it had nothing in it!!). Seeing how the vapors came into the house, I would guess you got to be getting some into the cab. Granted my truck being closed up in a garage didn't allow the smell to dissipate....

Re: Venting....
 

Man I don't know. The truck is out side all the time. It's not bad at all now, I can live with it but I would really like to figure out what has changed since having the tank cleaned out. It's just got me wandering.
I guess it could be the vapor is just coming back into the truck but who knows. I may have to get me a canister. Mount it up under the truck in the back some place.:chevy:

Re: Venting....
 

Gee Andy, have some fun and put it in the right place - behind the darn battery bracket / on the inside fender! It SOOOO much fun getting that battery tray out of there LOL


If anything, it is WELL protected in that little cubby hole ;-)

Re: Venting....
 

:lol::lol::lol::lol::lol:

Na, man if I do it it's going up inside the frame out back some place. That way the smell will always behind me.