gmkeegan Posted March 28, 2016 Report Share Posted March 28, 2016 so i'm doing some work on my 240z and wanted to know do i need to use a gas return line? thanks guys! Quote Link to comment
datzenmike Posted March 28, 2016 Report Share Posted March 28, 2016 If it has one yes. But... I don't think there were return lines until '75 and the EFI L28s. The will be a tank vent for fume collection. Don't confuse this with a return line. Quote Link to comment
gmkeegan Posted March 28, 2016 Author Report Share Posted March 28, 2016 If it has one yes. But... I don't think there were return lines until '75 and the EFI L28s. The will be a tank vent for fume collection. Don't confuse this with a return line. there are two lines running from the tank up to the carbs i thought the one was a fuel line and the other was a return line.. i could be wrong Quote Link to comment
datzenmike Posted March 28, 2016 Report Share Posted March 28, 2016 I think the SU's only had an incoming fuel line. Early system Engine off, non vented fuel tank cap. When evaporated fumes built to a certain pressure level, a valve allowed them into the engine crankcase for storage. Next time the engine is started the PCV draws these fumes into the intake and they are burned. At the same time as the gas tank empties air travels into the tank to replace the fuel removed. The left inner fender will have a flow guide with three hoses to it. One from the tank (vent) one to the crank case vent pipe (left side of block behind the exhaust manifold that goes to the PCV) and one to the air filter so return air is filtered. Later models stored the fumes in a charcoal canister. 1 Quote Link to comment
darrel Posted March 29, 2016 Report Share Posted March 29, 2016 yes, they do have return line. Quote Link to comment
gmkeegan Posted March 29, 2016 Author Report Share Posted March 29, 2016 yes, they do have return line. do i need to keep it or can i cap it off? i know the carb will stop the flow of gas if the bowl if full but will it mess up my gas pump? Quote Link to comment
datsunaholic Posted March 29, 2016 Report Share Posted March 29, 2016 It won't mess up the pump, but if it truly had a return line the point is to keep recirculating fuel to avoid vapor lock. Quote Link to comment
darrel Posted March 30, 2016 Report Share Posted March 30, 2016 http://www.classiczcars.com/topic/17542-treating-insideoutside-of-gas-tank-with-por15-products-and-removing-evaporation-tank/#comment-140973 Quote Link to comment
datzenmike Posted March 30, 2016 Report Share Posted March 30, 2016 I think the SU's only had an incoming fuel line. Yes, they do have a return. Found it. Definitely keep it. Quote Link to comment
gmkeegan Posted April 12, 2016 Author Report Share Posted April 12, 2016 Yes, they do have a return. Found it. Definitely keep it. thanks Quote Link to comment
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