1st Gen gas tank question

[fear_nothing]

So I've finally sourced a new (to me) gas tank to replace my leaky metal tank. The newer tank pictured first has hose attachments (pictured in item 1 & 2) that my current tank doesn't use. I'm running a plain ole carbureted 350 nothing fancy, no fuel injection. I would assume the unused connections can be capped?

thanks!

new

old

 

[chulisohombre]

I would hook it up same as the original and cap off the extras and make sure they are sealed good.

 

[1970worthog]

Mine has the same set up. Never looked to see where they all go
If i get a chance tm ill take a look

 

[Greg72]

I'll bet a lot of those "extra" connectors were for emmissions-related stuff.

It seems like when I pulled my 1972 tank there were a substantial number of hoses that didn't seem to do much except route fumes into a charcoal canister or some kind of evap collection system....

The Factory Assembly Manual would tell you conclusively.


-G

 

[fear_nothing]

So the float in my sending unit looks like swiss cheese. Has any one had any luck finding one locally? IE Napa, autozone etc? I see GMC Paul has one but I'd like to get one local if possible.

 

[chulisohombre]

Can you get one from where you got the tank. It may be specific kind. Otherwise if you can use a stock one lmc truck has them I believe. Other than that I have no clue if parts stores would be able to help without ordering it out. Not a normal in house part that they would keep on the shelf.

 

[bp71k5]

Any parts store can get them.

The extra ports are for vents. The k5 has a vent pipe in the bed that uses them. You need at least one vent somewhere.

The thing you marked vent, is actually a big vent for the filler cap when the cap is off and you are filling the tank. You'll need one of the small ones for the normal vent that's used during normal operation while the gas cap is on.

 

[fear_nothing]

Any parts store can get them.

The extra ports are for vents. The k5 has a vent pipe in the bed that uses them. You need at least one vent somewhere.

The thing you marked vent, is actually a big vent for the filler cap when the cap is off and you are filling the tank. You'll need one of the small ones for the normal vent that's used during normal operation while the gas cap is on.

Ok that makes sense. How and where do I run the smaller vent hoses?

Local parts stores were a complete bust
AutoZone
Napa
Discount Auto
Car Quest
Pep Boys

All were more than happy to sell me a Sending unit for as high as 130 bucks. Yah right. The shipping was more than the part cost - lets hope GMC Paul comes through!

 

[Agent_Orange]

Ok that makes sense. How and where do I run the smaller vent hoses?

Local parts stores were a complete bust
AutoZone
Napa
Discount Auto
Car Quest
Pep Boys

All were more than happy to sell me a Sending unit for as high as 130 bucks. Yah right. The shipping was more than the part cost - lets hope GMC Paul comes through!

mount the tank vent to the underside of the truck in a area that will not see a lot of dirt, water, grime... even better would to be put a small filter on the end of the line just to keep junk out of your tank.

 

[bp71k5]

Ok that makes sense. How and where do I run the smaller vent hoses?

Local parts stores were a complete bust
AutoZone
Napa
Discount Auto
Car Quest
Pep Boys

All were more than happy to sell me a Sending unit for as high as 130 bucks. Yah right. The shipping was more than the part cost - lets hope GMC Paul comes through!

Strange, my Kragens auto parts had one on the shelf for ~$50

 

[fear_nothing]

Strange, my Kragens auto parts had one on the shelf for ~$50

The part float gmc pauls worked out fine. I may soon get to experience a working gas gauge.

So it was suggested that I put some kind of filter/vent on the two extra connections on my newer gas tank. As pictured (see blue part) I found a pcv valve(s) that fit. Will that provide the right amount of venting? Also the new tank sits up much higher in the frame rails than an OEM tank. The tank is snug, it doesn't move around.... do I need to worry about rubbing from the gas or filler lines?

as always thanks!

 

[bp71k5]

Since pcb valves are only one way valves they won't work. The tank needs to allow pressure to be relieved and not draw a vacuum. If your charcoal canister still hooked up, you can run them there, or I put a breather cap from an a transmission on there. I've heard a fuel filter works ok too.

I had a clogged vent and experienced a huge rush of gas fumes on a trail when I went to check out what the strange "hissing" noise was from my gas cap.