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Replacement plastic rear tank and EFI return line

OX1

Bronco Guru
Joined
Aug 26, 2003
Messages
3,469
I have a "newer" (8 years old maybe) rear stock capacity plastic tank.
There is a boss that sticks out forward of the fill vent line.
It appears you could drill and tap this, possibly for an EFI return line.
Any reason this would not work?
 

Cortez

Bronco Guru
Joined
Jan 29, 2009
Messages
1,193
I used an after market return line plumbed into my filler neck. Just an idea if you don't want to drill the tank
 

vtboy51

Sr. Member
Joined
Aug 26, 2016
Messages
389
My metal replacement tank had 2 small nipples capped off right next to the Filler and vent connection. I used one of them for my efi return.
 

Toddpole

Sr. Member
Joined
Jan 2, 2008
Messages
832
My metal replacement tank had 2 small nipples capped off right next to the Filler and vent connection. I used one of them for my efi return.

I did the same with my stock tank. The result was flooding problems caused by high fuel pressure. The small tube/nipple couldn't flow enough and acted like a regulator. I installed a T at the tank and used both connections on the tank. No problems since. In hind sight I probably should have made the connection at the filler vent hose. It's much larger (about 5/8") and can handle the flow.
I just returned from Colorado. While there, every time I took the gas cap off to fill the tank, I got a whoosh of air rushing in. I plan to move the return to the filler vent and plumb a charcoal canister to the small tubes on the tank.
 
OP
OP
O

OX1

Bronco Guru
Joined
Aug 26, 2003
Messages
3,469
I did the same with my stock tank. The result was flooding problems caused by high fuel pressure. The small tube/nipple couldn't flow enough and acted like a regulator. I installed a T at the tank and used both connections on the tank. No problems since. In hind sight I probably should have made the connection at the filler vent hose. It's much larger (about 5/8") and can handle the flow.
I just returned from Colorado. While there, every time I took the gas cap off to fill the tank, I got a whoosh of air rushing in. I plan to move the return to the filler vent and plumb a charcoal canister to the small tubes on the tank.

Thanks for all the replies

What size fitting did you try first? Being a plastic tank my vent line is pretty small, ID wise.
I wasn't crazy about the idea of adding a T to fill line.

I ended up tapping the extra boss for a fitting with 3/8 barb. I drilled out inside of barb as far as I could.
There is another boss, tapped already, that I hope to use as a transfer point from side tank (eventually).

Maybe I'l hook up pump, lines, and throttle body to the tank, before
I put the tank back, to see if the pressure spikes.


20170810_221532.jpg
 

vtboy51

Sr. Member
Joined
Aug 26, 2016
Messages
389
I did the same with my stock tank. The result was flooding problems caused by high fuel pressure. The small tube/nipple couldn't flow enough and acted like a regulator. I installed a T at the tank and used both connections on the tank. No problems since. In hind sight I probably should have made the connection at the filler vent hose. It's much larger (about 5/8") and can handle the flow.
I just returned from Colorado. While there, every time I took the gas cap off to fill the tank, I got a whoosh of air rushing in. I plan to move the return to the filler vent and plumb a charcoal canister to the small tubes on the tank.

How soon did you experience the flooding problems. I've only put on 10 miles with the setup, and hate to find out i've got a problem on a long trip.
 

Toddpole

Sr. Member
Joined
Jan 2, 2008
Messages
832
How soon did you experience the flooding problems. I've only put on 10 miles with the setup, and hate to find out i've got a problem on a long trip.

It was quite strange. It ran great for a year or two of wheeling. I trailer to wheeling spots and typically only drive 2-5 miles then shut it off while several go thru/over the obstacles. Fire it up when it's my turn. Lots of short runs with no street use. One weekend it decided to act up. Put a T in the line just before it returned into the tank and all was good. I have a 5/16" EFI return line from engine fuel rail to tank. The two ports on the steel tank fit 1/4" hose IIRC. This makes the I.D. approx. 1/8". You can see how that will restrict the flow.
 
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