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Discussion Starter #1
I have a 1986 USA turbo esprit that had been in an engine fire. The engine was toast (literally), so I went to a more modern alternative 4 cylinder supercharged engine (2006 Cobalt LSJ engine). With engine in and electronics sorted out, my last task is fueling. Am using a return fuel system from the injector rail (using an adjustable fuel regulator). I am now looking at plumbing my return line to the fuel tank.

The right had side (passenger side) fuel tank has a M12 banjo fitting w barbs on the top.

I was initially planning on taking my return fuel line to this banjo fitting

Does anyone know if there is a tube extension inside the tank from the banjo fitting to the bottom of the tank? I want to make sure that my return gas line is discharging at the bottom of the tank versus just discharging at the top (want to minimize bubbles into the fuel by discharging at the bottom)

I replaced the wood that was holding the gas tank w aluminum plate and have mounted all my electronics to this aluminum plate (and have sandwiched the tank with rubber door matts). In lieu of taking off all the electronics and aluminum plate to get access to the fuel level sensor to confirm if the tube goes to the bottom of the tank I thought I would first pose this question
 

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I did the same thing with my 86, added the S4 injection hardware, used the original return fitting as you described. There is a baffle under the return fitting in the tank, so no doesn't go to the bottom of the tank.
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sigh

removed dumbass response...
 

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Wingless Wonder
1988 Esprit Turbo
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That fitting is for the return line from the fuel rail to the tank.
Correct, even for the original Bosch FI cars, #70 is a Fuel Return Line.

I have no idea if there is a tube under the banjo fitting that feeds into the bottom of the tank. ???

Where does the fuel pump for the Cobalt LSJ GM conversion draw fuel? Are bubbles a REAL concern, or is it a Theory VS Practice thing? “In theory, theory and practice are the same. In practice, they are not.”


Esprits with GM MPFI have a 'well' or cylinder under the tank where the pump sucks fuel, was that why they decreased the capacity 2 gallons to adapt the GM pump? I see that the GM pumps had a return line #5 with a tube to the bottom.
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Guys, I put a bore scope down the tank fitting for return line. There is no tube, just a baffle open on two sides to allow the returned fuel to just gravity feed down into the tank.
 

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Discussion Starter #8
I'm going to try and use the bottom drain plug on the passenger tank as my return line. There was a technical video from Aeromotive that demonstrated what was happening when the return fuel line was not submerged. They were monitoring the performance of the pump and did a comparison of submerged vs not submerged for the return fuel line feed
 

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Discussion Starter #10
does anyone know what the drain plug size is? I thought M10 x 1.0 but that did not work. I then tried 3/8 x 24 and that did not work. Is it 3/8 x 28?
 

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Dreaded Prior Owner
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1/8" BSP is a 28 TPI thread, so that's likely what you're looking at.
 
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