What to do with gas tank vent when all emissions components are deleted?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,875
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
I am replacing the gas tank on my 1980. The.. previous owner was my grandfather. There are three nipples coming off the gas tank sending unit thingy, and one of them I presume is a vent for the fuel vapor for the canister. That stuff is since been long gone on the truck. He had it plugged, but Im guessing some of my fuel issues was having a gas tank that couldn't vent... on top of the rust and bad gas gauge unit haha!

What should I do to it?
 

ali_c20

Full Access Member
Joined
Sep 20, 2016
Posts
1,348
Reaction score
1,952
Location
Austria
First Name
Alexander
Truck Year
1974, 1979
Truck Model
C20, K5
Engine Size
350, 350
You could leave it plugged and buy a vented gas cap.
 

Dan Miller

K15SG
Joined
Sep 11, 2019
Posts
385
Reaction score
577
Location
Indiana
First Name
Daniel
Truck Year
1978
Truck Model
K15
Engine Size
350
I am replacing the gas tank on my 1980. The.. previous owner was my grandfather. There are three nipples coming off the gas tank sending unit thingy, and one of them I presume is a vent for the fuel vapor for the canister. That stuff is since been long gone on the truck. He had it plugged, but Im guessing some of my fuel issues was having a gas tank that couldn't vent... on top of the rust and bad gas gauge unit haha!

What should I do to it?
My tank has a ventcap like on an axle vent tube . It has only one vent line coming out of it tho, but it will vent. I will take a pic when I get home
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,875
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
For the time being a drilled a tiny hole in the gas cap(just becsause I didnt have a vent on hand). where can I get a properly vented gas cap?
 

Dan Miller

K15SG
Joined
Sep 11, 2019
Posts
385
Reaction score
577
Location
Indiana
First Name
Daniel
Truck Year
1978
Truck Model
K15
Engine Size
350
My tank has a ventcap like on an axle vent tube . It has only one vent line coming out of it tho, but it will vent.
You must be registered for see images attach
 
Last edited:

Edward Maxwell

Junior Member
Joined
Jun 28, 2019
Posts
19
Reaction score
2
Location
Right side of WA
First Name
Edward
Truck Year
86
Truck Model
K30
Engine Size
502
I bought check valve vents, built brackets and put them between the rear quarters and the inner bed side as high as I could. I had them just above the tanks on the frame when I deleted all my stuff and the first time I pumped cool gas out of the ground on a hot summer day my $4/gallon ethanol free expanded and ended up on the ground.

The link above is the ones I used.
 
Last edited:

Edward Maxwell

Junior Member
Joined
Jun 28, 2019
Posts
19
Reaction score
2
Location
Right side of WA
First Name
Edward
Truck Year
86
Truck Model
K30
Engine Size
502
Oh DO NOT ask butt pirate 4x what to do as those hillbillies will chastise you and tell you that you, expecting them to engineer your way out of this problem is pathetic.

That was my experience, it sucked.
 

Frankenchevy

Proverbs 16:18
Joined
Jan 3, 2018
Posts
6,098
Reaction score
7,806
Location
USA
First Name
Jeremy
Truck Year
Square
Truck Model
CUCV
Engine Size
Small
The only downside to a check valve is that it only operates in one direction. Theoretically, you’d want it to operate in both directions. To vent positive pressure accumulation and to draw air in to displace the fuel being drawn out. Probably not a huge deal in a lower fuel demand engine, though.
 

Edward Maxwell

Junior Member
Joined
Jun 28, 2019
Posts
19
Reaction score
2
Location
Right side of WA
First Name
Edward
Truck Year
86
Truck Model
K30
Engine Size
502
Per Tanks inc website these valves are open to atmosphere to relieve pressure and vacuum avoiding performance issues and potential damage to the tank until you park your vehicle upside down at which time it checks and allows the driver time to depart the vehicle safely.
 

Frankenchevy

Proverbs 16:18
Joined
Jan 3, 2018
Posts
6,098
Reaction score
7,806
Location
USA
First Name
Jeremy
Truck Year
Square
Truck Model
CUCV
Engine Size
Small
Per Tanks inc website these valves are open to atmosphere to relieve pressure and vacuum avoiding performance issues and potential damage to the tank until you park your vehicle upside down at which time it checks and allows the driver time to depart the vehicle safely.
Okay so you’re referring to a rollover vent like I linked to earlier on in the thread. That’s what I have.
 

norman baker

Member
Joined
Dec 2, 2018
Posts
45
Reaction score
12
Location
ellijay,ga
First Name
norman
Truck Year
1976,1981,1982,1984 1985
Truck Model
k20 ,c10 ,c10,c20, c10
Engine Size
none, 250 ,305, 454, 305, 454 ,
i use mine as a return line from the carb low pressure , but replace the hose it is only rated for vapor, not liquid fuel.
 

texasmike

Full Access Member
Joined
Sep 18, 2018
Posts
245
Reaction score
175
Location
Conroe Texas
First Name
Mike
Truck Year
1984
Truck Model
C10
Engine Size
305
When my truck is back on the road, I'm going to put my canister back on and reconnect the fuel tank vent line. Although a vented cap would probably be easier and just as good, like you, I don't know exactly what cap to buy that would fit and work properly.
 

C10MixMaster

Full Access Member
Joined
Dec 6, 2016
Posts
756
Reaction score
1,428
Location
Kingman AZ
First Name
Ben
Truck Year
1977
Truck Model
C10 BIG10
Engine Size
ZZ4 350
When my truck is back on the road, I'm going to put my canister back on and reconnect the fuel tank vent line. Although a vented cap would probably be easier and just as good, like you, I don't know exactly what cap to buy that would fit and work properly.

I believe an 84 is a screw in gas cap, if so i dont think they sell a vented screw in cap. If it uses a cap with 2 ears on it you need one from a 73-74 that didn't have an evap system.
 

Frankenchevy

Proverbs 16:18
Joined
Jan 3, 2018
Posts
6,098
Reaction score
7,806
Location
USA
First Name
Jeremy
Truck Year
Square
Truck Model
CUCV
Engine Size
Small
drill a 1/16" hole in any gas cap and voila, vented cap.
 

Latest posts

Forum statistics

Threads
44,416
Posts
957,129
Members
36,753
Latest member
TheRigLivesOn
Top