DoubleNickels
SILVER Star
Hey everyone. This seemed good enough tech to split out on its own, thought I'd share.
What to do if your fuel tank pickup tube is fully clogged and no amount of pushing/pulling/blowing/sucking will dislodge whatever evil chunk of bastardry has taken residence in the pickup tube? Give up? Pay for a custom aftermarket tank? Buy another used tank and pray it doesn’t have the same issue? Nope nope nope. Cut into the tank, risking a fireball and throwing metal shards around and ruining whatever lining remains intact, then being on the hook to weld up a watertight tank? Nah. Here is my path toward a solution.
The first thing I tried was to simply move my soft line (right where the gas exits the tank) from the pickup tube to the return tube. My carb doesn’t sport a return port so that entire hard line and soft line was just capped off. Well, spoiler alert, moving your soft line to that (return) tube just won’t work, because this return tube empties into the tank a few inches above the tank’s bottom. Meaning it might work if the tank is 80%-100% full, then the fuel level will drop too low to enter it. Lame.
Credit goes to local legend Jim Mack (@J Mack ) for suggesting a solution commonly practiced in other vehicle cults: install a new pickup tube entirely, this time going right through the fuel sender cap.
There’s a catch here, there really isn’t much room. Typically, you can install what is called a bulkhead fitting into a tank wall to allow attachment of tubes/hoses. A bulkhead is essentially a hollow piece of all thread, where you pass the all-thread through a drilled hole and use nuts to secure it relative to the wall. Do a quick search for bulkhead fittings and you find every make model and flavor, depending on the specific size you need and the “ends” you desire (hose barb, pipe thread, flare fitting, etc.). Something like this:
If the sender cap was thicker you could pipe-tap directly into the cap and call it good, i.e. no locking nut required on the inside. The problem is the steel is too thin to feel good about the rigidity and longevity.
I decided to use a 5/16” compression union fitting to make my own bulkhead fitting. I did this for a few reasons:
In my case I wanted a single 5/16" OD tube to pass clean through, which meant I could drill out the middle step in the union (there’s a slight shelf there) and also meant I could get rid of one locking ferule. I cut the end off of one locking nut so I could use it as my bulkhead lock. It once looked like this, and by cutting it down (removing the red area) I essentially made a skinny little jam nut:
I used hot glue to place the jam nut in position and verify the sender cap would attach to the tank without interfering. With that confidence under my belt I carefully drilled a hole in the correct location on the fuel sender cap – the drill size I used was 1/2", which resulted in a hole to match the 1/2-20 male thread present on the union fitting's body. The threads very slightly engaged with the thru-hole walls, meaning it took some rotating of the fitting to get it in place. This is desirable as it lessens the demand on the wimpy little jam nut to maintain placement.
At this point I chose to install a pickup tube filter. There are various embodiments of this, but here is one I found on Amazon which (I believe) is originally intended for an old Ford Mustang. Part number MA15008:
What to do if your fuel tank pickup tube is fully clogged and no amount of pushing/pulling/blowing/sucking will dislodge whatever evil chunk of bastardry has taken residence in the pickup tube? Give up? Pay for a custom aftermarket tank? Buy another used tank and pray it doesn’t have the same issue? Nope nope nope. Cut into the tank, risking a fireball and throwing metal shards around and ruining whatever lining remains intact, then being on the hook to weld up a watertight tank? Nah. Here is my path toward a solution.
The first thing I tried was to simply move my soft line (right where the gas exits the tank) from the pickup tube to the return tube. My carb doesn’t sport a return port so that entire hard line and soft line was just capped off. Well, spoiler alert, moving your soft line to that (return) tube just won’t work, because this return tube empties into the tank a few inches above the tank’s bottom. Meaning it might work if the tank is 80%-100% full, then the fuel level will drop too low to enter it. Lame.
Credit goes to local legend Jim Mack (@J Mack ) for suggesting a solution commonly practiced in other vehicle cults: install a new pickup tube entirely, this time going right through the fuel sender cap.
There’s a catch here, there really isn’t much room. Typically, you can install what is called a bulkhead fitting into a tank wall to allow attachment of tubes/hoses. A bulkhead is essentially a hollow piece of all thread, where you pass the all-thread through a drilled hole and use nuts to secure it relative to the wall. Do a quick search for bulkhead fittings and you find every make model and flavor, depending on the specific size you need and the “ends” you desire (hose barb, pipe thread, flare fitting, etc.). Something like this:
If the sender cap was thicker you could pipe-tap directly into the cap and call it good, i.e. no locking nut required on the inside. The problem is the steel is too thin to feel good about the rigidity and longevity.
I decided to use a 5/16” compression union fitting to make my own bulkhead fitting. I did this for a few reasons:
- The nuts used for compression are very minimal in dimension. You have an extremely limited landing zone for the tube pass-through and locking nut. Too close to the center and you hit the sender block – too far from center and you’d interfere with the fuel tank flange.
- Using a compression union meant I could run a hard line straight through the fitting, thereby optimizing pickup tube location relative to the tank bottom AND putting in an aggressive 90-degree bend where it exits the sender cap. You really don’t have much breathing room there before the bulkhead hits the underside of the fuel sender access door.
In my case I wanted a single 5/16" OD tube to pass clean through, which meant I could drill out the middle step in the union (there’s a slight shelf there) and also meant I could get rid of one locking ferule. I cut the end off of one locking nut so I could use it as my bulkhead lock. It once looked like this, and by cutting it down (removing the red area) I essentially made a skinny little jam nut:
I used hot glue to place the jam nut in position and verify the sender cap would attach to the tank without interfering. With that confidence under my belt I carefully drilled a hole in the correct location on the fuel sender cap – the drill size I used was 1/2", which resulted in a hole to match the 1/2-20 male thread present on the union fitting's body. The threads very slightly engaged with the thru-hole walls, meaning it took some rotating of the fitting to get it in place. This is desirable as it lessens the demand on the wimpy little jam nut to maintain placement.
At this point I chose to install a pickup tube filter. There are various embodiments of this, but here is one I found on Amazon which (I believe) is originally intended for an old Ford Mustang. Part number MA15008:
Several advantages going this route.
