Vapor Lines on Fuel Tank 240-Z

Contributed By: DAVE

Last Up-date 20 Jan. 2003

Hi Carl,
I found that it took a long time to fill my 73 gas tank (14 gal.) when the gas was above where the filler meets the tank (10 gal.).

Here are pics that show how I put a 76 tank in my 73.

If I was using an earlier tank I would cap and clamp the lower vent hose. This would trap a cup full of air in the tank when filling up with the passenger's side lower than the driver's side.

The expansion tank system has several drawbacks; notably a lot of hoses to get kinked or rotted, and a small vent coming out. I replaced the top vent with a 3/4" elbow and hose; this improved filling but not up to modern standards. The slope of a hose is important because gasoline can get trapped in a valley and block the movement of air.

So I removed the tank and found that the largest vent hose had a kink in it. To simplify and improve things, I spent $3 on household plumbing items and fuel hose, that you see in the pics. I used some of the old hose because it was in good condition.

I suspect the gas fumes will turn the plastic brittle so I will replace them with copper, but it has been over 4 months. Copper can be soldered or glued with a 2-part epoxy made for that purpose.

I opened the floor with a drill and sawsall so that the one vent line would slope upwards and have no valleys. That hole can be filled with foam, bondo, etc. and the rear trim panel covers it. You can run the hose under the floor and up through a hole to the filler, but fuel might get trapped in a valley and block air flow. Clean the tank and coat the inside and outside while it is off. Questions or suggestions?

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