The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

cerial · 08-13-2018, 08:53 PM

I am going the other way and putting a 72 tank into my 87 and came across this thread.

Here is my plan for the vent line routing;
Put a cap on the sending unit plugging that line.
Have the two ports on the drivers side connected with a brass T in between them
Have the passenger run over to the drivers side into the middle of a 2nd t that connects to the first (lower) T.

Then I have a line running all the way from the (Upper) T to the passenger side then the line does a 90 and goes up inside the B pillar then down before coming back and folling the fuel line through the floor and inside the frame rail to the 87's evap.

This should allow the truck to be on it's side or roof and little to no fuel to enter the evap line thanks to gravity.

For the fuel line I have something that seems like it should work.

I have the return line running to A high pressure T fitting with the tank feeding into the top of the T and the pump feeding from the bottom of the T. Now the circulating of fuel from the return back to the pump should siphon fuel from the tank and only as needed.

If I run the pickup dry then cavitation could happen but will resolve itself as the bubbles either return to the tank or are pulsed into the tbi creating a momentary lean.

I believe I will need to prime the system the first time. But once primed as lone as I don't run completely out Of fuel this should keep siphoning fuel from the tank into the loop and not require a second pump.

The pump will be pushing fuel. But as the T is above the pump any return fuel will be pushed against the backside of the pump so the "pulling" will be minimal. I am thinking it should gravity siphon and keep the loop full and when running the thing should find a psi where it will stop pulling fuel from the tank to keep the loop full . If I go hard throttle to nothing a surge may be sent back into the tank. But once back on the throttle it should continue to siphon and not be an issue.

Or I could be horribly wrong and only make it a mile and the thing starts to sputter.

Plan B is to just do the idea of taking it to a radiator shop and doing the 3 ports on the bottom of the tank to gravity feed into the pump. That being said I don't want to modify a bran new tank if I don't need to.

08-13-2018, 08:53 PM	#56
cerial Registered User Join Date: Mar 2014 Location: Ionia, MI Posts: 199	Re: EFI with factory Fuel Tank?? I am going the other way and putting a 72 tank into my 87 and came across this thread. Here is my plan for the vent line routing; Put a cap on the sending unit plugging that line. Have the two ports on the drivers side connected with a brass T in between them Have the passenger run over to the drivers side into the middle of a 2nd t that connects to the first (lower) T. Then I have a line running all the way from the (Upper) T to the passenger side then the line does a 90 and goes up inside the B pillar then down before coming back and folling the fuel line through the floor and inside the frame rail to the 87's evap. This should allow the truck to be on it's side or roof and little to no fuel to enter the evap line thanks to gravity. For the fuel line I have something that seems like it should work. I have the return line running to A high pressure T fitting with the tank feeding into the top of the T and the pump feeding from the bottom of the T. Now the circulating of fuel from the return back to the pump should siphon fuel from the tank and only as needed. If I run the pickup dry then cavitation could happen but will resolve itself as the bubbles either return to the tank or are pulsed into the tbi creating a momentary lean. I believe I will need to prime the system the first time. But once primed as lone as I don't run completely out Of fuel this should keep siphoning fuel from the tank into the loop and not require a second pump. The pump will be pushing fuel. But as the T is above the pump any return fuel will be pushed against the backside of the pump so the "pulling" will be minimal. I am thinking it should gravity siphon and keep the loop full and when running the thing should find a psi where it will stop pulling fuel from the tank to keep the loop full . If I go hard throttle to nothing a surge may be sent back into the tank. But once back on the throttle it should continue to siphon and not be an issue. Or I could be horribly wrong and only make it a mile and the thing starts to sputter. Plan B is to just do the idea of taking it to a radiator shop and doing the 3 ports on the bottom of the tank to gravity feed into the pump. That being said I don't want to modify a bran new tank if I don't need to.