Fuel line
Thread Starter
Racer
Joined: May 1999
Posts: 288
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Fuel line
While I was putting my new hoses on my new heater core I found what looks like a second fuel line. It was getting late so I didn't get a chance to follow it back to the rear of the car. It was cut and blocked off with a piece of rubber hose and a bolt. The car ran with it not hooked up. Do I need it or just leave it blocked off? :confused: :confused:
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,364
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Fuel line (rayray)
rayray -
I'd like to slightly modify what the others said:
The line is a vapor return line, and is used with fuel pumps that have 3 fittings on them. The small fitting on the pump returns excess fuel back to the tank, thus keeping fuel circulating through the fuel suction line at all times. This tends to reduce vapor lock tendancies. If you're not having vapor lock issues, you don't need the line. If you ever have vapor lock problems, you might want to consider installing one of the 3-fitting pumps and hooking up the line.
The other cool use for this line is when you're running an electric boost pump back at the tank. Electric pumps don't like to be dead-headed, and tend to have very short lifespans if they don't keep fuel flowing. For this reason, and to avoid vapor lock problems, you can run a fuel return line from a location very close to the carb through a small (about 1/8") oriface and back to the tank via the 1/4" return line. This allows you to run an electric boost pump with your mechanical pump, maintaining very good lifespan on the electric, and keeping nice, cool fuel flowing up to the carb constantly. Makes for a pretty neat fuel system....
I'd like to slightly modify what the others said:
The line is a vapor return line, and is used with fuel pumps that have 3 fittings on them. The small fitting on the pump returns excess fuel back to the tank, thus keeping fuel circulating through the fuel suction line at all times. This tends to reduce vapor lock tendancies. If you're not having vapor lock issues, you don't need the line. If you ever have vapor lock problems, you might want to consider installing one of the 3-fitting pumps and hooking up the line.
The other cool use for this line is when you're running an electric boost pump back at the tank. Electric pumps don't like to be dead-headed, and tend to have very short lifespans if they don't keep fuel flowing. For this reason, and to avoid vapor lock problems, you can run a fuel return line from a location very close to the carb through a small (about 1/8") oriface and back to the tank via the 1/4" return line. This allows you to run an electric boost pump with your mechanical pump, maintaining very good lifespan on the electric, and keeping nice, cool fuel flowing up to the carb constantly. Makes for a pretty neat fuel system....
