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Fuel Tank Vent

rcmbronc

Contributor
Bronco Guru
Joined
Dec 15, 2003
Messages
2,692
Loc.
Tomah WI
I have a little tank vent questions. I have a 76 with efi. The tank has a small vent line and a non-vented gas cap. The vented gas caps from earlier models do not fit the later filler necks. With EFI moving alot of fuel it seems to once in a while be more than the vent line can handle. Any ideas? I was thinking of taking the larger vent line off the filler neck and putting a filter on it and plugging the small line on the filler neck. Every once in a while I get a stutter and I think it is a lack of venting, but not sure. I also have a LP pump to an accumalator to a HP pump. I need to try to restict the return flow to the tank from the LP pump to try to reduce the fuel movement.

Anyone know a vented gas cap that fits the newer years filler neck?
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,316
I don't think the vent is your problem. Yes the pump pulls a lot of fuel from the tank, but it also puts fuel back into it at the same time. The net result is flow that was similar to a crab'd setup. Restricting flow back to the tank is not going to do anything good. How do you have the return line going into the tank? If the return is dumped into the top of the tank then the fuel may be getting airated. Return lines should dump to the bottom of the tank to prevent this.
 

JWMcCrary

Contributor
Bronco Guru
Joined
Oct 14, 2004
Messages
5,001
I took a dremel and modified my filler necks to use the vented caps. Took them off the truck and worked them until I could get the vented caps to go and and off.

I am carbed...not EFI.
 
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