Fuel tank venting

[TurboBuRick]

Rick.. I like that.. "If fuel can be fed into the tank wot, your vent should be good enough to accommodate the demand of the motor."

Trick would be to make sure the neck was sealed to the gas spicket when doing this.

LOL! you like that? :biggrin:

If the flapper insert in the neck is in place you not venting much back through.
I went through this before. Had the rubber vent line cross over the hard lines when I put the gas tank back up in the car. Could never figure out why the car would not fill with fuel fast. After discovering and fixing the pinched vent line, it will now take the gas nozzle wot no problem.

I also had wot issues with afr's but was real inconsistant. Made it hard to pinpoint the actual cause.

FWIW my o2

 

[TurboBuRick]

good info....could this be a sign of a bad gas cap also since they are vented?

Surej, I don't think the cap is suppose to be vented. Is it?

 

[GNVYUS 1]

Interesting topic, glad I had Turbofabricator help me out on my fuel sender.:biggrin:
I used to run a vented gas cap thinking it would be overkill and eventually switched it out. Problem with the modern caps (why I ditched it) they stopped venting OUT fumes from the tank and only draw IN air to the tank due to, "Harmful Gases". :frown:

RockAuto still has the ACDelco one for our stock 84-92 GM #22525300 (Delco #GT-172).
RockAuto Parts Catalog

RmvBfrFlght, thanks for that post and part #, I'm swapping my crappy fuel filter vent line for that this year.

Jeff Rand, do you believe you could've achieved the same fuel pressure end result with a properly vented gas cap?

 

[aminga]

I bet if you get a car with a plugged up vent line to the tank.. you can pull your hair out trying to determine why it starves for fuel at WOT.

And if you're replacing fuel lines and block the vapor line and leave the return line unattached you can dump a lot of fuel on the garage floor when the garage gets warm.

 

[nodude]

Where the metal fuel return line enters the sending unit there is a small slot shaped opening. Should this slot be drilled out to the i.d. of the
return line to improve return line flow and prevent back pressure?

 

[Chuck Leeper]

Old thread, new ??
The return line on my 87T has been kinked, just at the firewall area of the frame. I don't run the canister, so I'm thinking, drop the tank, drill the vent to line size, use the vent line to replace the return line. The honk valve is now a discontinued item w/ GM. I guess I'll use a fuel filter.
No dual pumps. This car is stock, so won't be much quicker than lo 10's. The ? is, will this work?

Back under my rock...

 

[69RSCLONE]

Vent line is likely rusted inside and will contaminate the fuel. Just an FYI

 

[Chuck Leeper]

Vent line is likely rusted inside and will contaminate the fuel. Just an FYI

Could be.
I'm going to replace it w/ 3/8 hardline, and a new, 3/8 feed.
Have to drop the tank anyway..

 

[SHADOWII]

Would a pcv valve work? They come in a variety of diameters and spring pressures.

 

[Scarab]

Well mine doesnt have the canister on it and it builds pressure when I drive it. If I lossen the cap pressure comes out. What should I do?

 

[Chuck Leeper]

Well mine doesnt have the canister on it and it builds pressure when I drive it. If I lossen the cap pressure comes out. What should I do?

Hook the vent line back up and put a fuel filter at the ft end to allow the tank to breathe...

 

[The_Six]

Alot of guys ues these now instead of the filter https://www.amazon.com/Compatible-1...bm2Afwn6VyR26KENWLmlPrSi3VySzYS4aAvNyEALw_wcB

 

[Scarab]

I took the cap apart and removed the plunger. Vents both ways now. So much easier than dealing with the hose.

 

[Chuck Leeper]

The unvented cap is used for 2 reasons.
Emissions control.
Prevent fuel splash under hard accel.
Yours leak?