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Fuel tank return inlet


h4nsm0l3m4n

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I was working on redoing some of my fuel pump/surge tank system when I found something wierd. The fitting on the left side of the tank is acting normally - soon as I take off the line fuel comes rushing out. When I do the same for the right side fitting, nothing happens. I know its possible that the pick up tube on the other end is all clogged up with something but I'm trying to make sure I'm not missing something before I put the car back together. Is there no check valve or other device keeping fuel from coming out of the tank through the return line?

 

I started looking into it a little more and another thing I noticed was that my tank did NOT match the tank in the FSM (below).

74_260z_fuel_tank.gif

My car is a 74.5 (12/74 build date) so I'm used to it having bits and pieces off the 75 model year car. I found a picture of the 75 fuel tank (below) and visually it seems to match up with the tank I have.

schematic.gif

My question here is what is the thing inside the tank on the return line? It looks like the tank outlet is a pick up tube, but the return line tube runs farther inward and down into a cup looking thing. What is that for? Would it have any impact on my earlier question?

 

These might be trivial/stupid questions, especially since I havent had any issues with the fuel tank previously. I'd like to avoid unnecessarily dropping the tank but at the same time I dont want to just put it back together without understanding what is going on.

Edited by h4nsm0l3m4n
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I was working on redoing some of my fuel pump/surge tank system when I found something wierd. The fitting on the left side of the tank is acting normally - soon as I take off the line fuel comes rushing out. When I do the same for the right side fitting, nothing happens. I know its possible that the pick up tube on the other end is all clogged up with something but I'm trying to make sure I'm not missing something before I put the car back together. Is there no check valve or other device keeping fuel from coming out of the tank through the return line?

 

I started looking into it a little more and another thing I noticed was that my tank did NOT match the tank in the FSM (below).

74_260z_fuel_tank.gif

My car is a 74.5 (12/74 build date) so I'm used to it having bits and pieces off the 75 model year car. I found a picture of the 75 fuel tank (below) and visually it seems to match up with the tank I have.

schematic.gif

My question here is what is the thing inside the tank on the return line? It looks like the tank outlet is a pick up tube, but the return line tube runs farther inward and down into a cup looking thing. What is that for? Would it have any impact on my earlier question?

 

These might be trivial/stupid questions, especially since I havent had any issues with the fuel tank previously. I'd like to avoid unnecessarily dropping the tank but at the same time I dont want to just put it back together without understanding what is going on.

 

Not a dumb question - as I recall the FSM doesn't talk about it at all.

 

The cup-looking thing should be (at lest it is on my 78) a swirl pot. They feed the return line through a small jet pump into the swirl pot to keep it filled with fuel, The pickup line then draws its fuel from the pot, so that it always has a head of fuel over it. The pickup tube has a filter over it, so it _shouldn't_ clog up from stuff in the pot, but its still possible that something has rusted and clogged internally.

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Thanks for the reply, very interesting. If my understanding here is right, even if there is a swirl pot in the return line pickup the fuel should still come out of the line when I open it up right? If thats the case then I guess something is clogged up and a good tank cleaning is in order. This is strange because my fuel has always been pretty clean and I've never had issues with this before. Oh well :rolleyes:

Edited by h4nsm0l3m4n
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