Need help for the connection of Evaporation Tank 's Evaporation hose ..1971 240 z

[suleymantezgul]

I couldn't find this vapor line (Evaporation Line) in my 2/71 240z.Would give a little more info ?.. What I am interested is the location of exit from the vapor line coming out of the expansion tank.Thanks

[Blue]

The line runs from the tank area to the flow device just below ballast resistor in this picture.

72 FSM excerpts below (Emission chapter)

[suleymantezgul]

My 240Z is a 2/71 ..I am trying to put the fuel tank and vapor tank together. There is a evoparation hose for ventilation of the expansion tank,and as seen in schematics of later models that connects to carbon canister all the way to he engine bay.

There is no carbon canister and a third line going the engine bay in my car.

As far as gathered from the information I found,There should be a hard line going through the fender for ventilation.

I need information where this hard line is located and exits through the fender.


Thanks for your help

[tlorber]

Im not sure that the 240's had then carbon canister-neither of my '73s has them. They do have a vent line that runs up to the engine compartment, through a spring loaded check valve, and into the air cleaner. When the vapor pressure builds up high enough, it overcomes then spring and gets sucked I to the engine.

[Jarvo2]

The geniuses at Nissan used different sized hoses for each of the vent tubes. This seems like a pain, but it actually makes connecting the right hose to the right connection much easier! At the bottom of this blog post (Dave's 1972 Datsun 240z: Smelly Situation) you will find several diagrams of what size hoses go where. Good luck!

[jfa.series1]

Here's a picture of the evap tank hookups to the fuel tank. Your evap tank may be metal but the connections should be the same. Look closely at the top left of the evap tank for a small hose - this one connects to the steel fuel vapor line running back from the engine bay. At the bottom left of the evap tank is another small hose that connects to a small pipe on the top of the fuel tank - this is the return line for any fuel that condenses in the evap tank. You will have to have this hose in place on the fuel tank before you raise it back into position. I'll look for or take some pics of the engine bay vent line connections for another post. On the major tank vent hoses I used genuine Nissan parts but others have substituted generic fuel line hoses with great success.

[jfa.series1]

Here is the vapor check valve that should be on your fender under the coil and ballast resistor. The top hose comes from a small pipe in the center of your air filter box. The lower hose comes from a small pipe on the large crankcase breather pipe coming off the engine block. The second pic shows the return hose onto the steel line returning to the rear of the car. The steel line should be visible along the left rail.

I hope all of this helps you solve all your plumbing questions. Good luck with your repairs.

[Mikes Z car]

This is a picture of a 1/1972 car evaporator tank laying on its side. The vent line heads for the gas tank after it exits the bottom of the fender next to the filler hose.
The rubber vent line was pulled off of its connector on the evap tank before this picture was taken.

[suleymantezgul]

Thanks for allyour information and photoes.I am going to the shop and check again for the piping.But Flow Guide Valve is not there (the bolt is still there under the resistor) that I know. Any suggestions what I should do without Flow guide valve ?.At the moment I am not sure either that the steel pipe is still existing.

Also,where this steel pipe starts on the tank side.Does it run with the two fuel lines to the engine bay ?.What is the size of the pipe ?.

[Travel'n Man]

This may help with the tank side

[Blue]

The steel line runs in parallel with the fuel send and return steel lines. It runs from the front of the differential area to the driver wheel well area in the engine compartment.

[Freez74]

I wonder why the tanks in these cars have 3 vents, one should be enough.

[Mikes Z car]

To me it looks like they were making sure all trapped air (some would be gas vapor) at the top of the tank is taken out of the tank and put in the evaporator tank, I assume for environmental reasons to prevent it from escaping to the atmosphere. Picture the tank rocking forward and back and side to side as might happen if the Z was going down the road or is parked on an incline as it is being filled with gas and how those vents are placed so that one is always at the top of any bubble of trapped air that might form. Why getting the trapped air out might be important I have no clue.

[Blue]

The tank to evaporator hoses and filler pipe circulate the gas from liquid to vapour to liquid. I thinks the four hoses are for drain back and for collection at the highest locations. The three pickups on the tank seem to prevent trapped pockets of gas vapour

The tank to engine compartment line is the only opening in the system where fresh air can be drawn back to the tank to replace the fuel that is consumed when running. The fresh air is drawn through the carb's air filter box.

When the car is stopped and off, the line to the engine compartment also sends fuel vapours to be be stored in the crank case (when heat causes the fuel tank pressure to increase)

The flow guide valve either sends tank fumes to the crank case or fresh air to the tank.

[tlorber]

I recently replaced all hoses on one of my Z's. It appearance that the multiple vapor hoses are needed due to the baffling in the tank (which minimizes gas sloshing around). The baffles essentially create separate pockets at the top of the tank, and each needs to be vented. It seems to me that they could have collected them together in a manifold and then sent one or two hoses back to the recovery tank, but why make it easy on yourself?

[nix240z]

look at your rubber insulators that hold the fuel and brake lines, if the ones in the transmission tunnel and the one in the center of the firewall above the transmission have 4 holes then you have or had the piping for the flow guide valve. If only three holes then no flow guide valve.

steve

[jfa.series1]

Here's a pic for the guidance from Steve. The vapor return line is on the driver's side frame rail.

[Stanley]

I can't believe very much fumes are going to make it out of the evap tank, down the long 1/4" tube, and out into the engine bay, especially since air is supposed to be going the other way when you're driving. Nice idea, but I doubt if it does very much except vent the tank, which is necessary.

If it turns out you have the tube (shown clearly in the post above) but no flow valve, you could just leave it as is. If the tube is disconnected at the evap tank, maybe put some emission hose on it and let it go down under the car, to keep any fumes out of the cabin.

Anybody with a flow valve, give that thing a good blast of carb cleaner so it actually works.