Fuel System Picking up Air
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Freshman User
Joined: Oct 2015
Posts: 45
Likes: 0
From: Hampshire, UK
Fuel System Picking up Air
Hi all,
Just after a couple of new ideas, as I can't track down my air leak.
'66 F100 with in cab gas tank.
When the tank is below 1/2, there starts to be a small amount of air getting into the fuel line. (Can see it bubbling in the filters, and get misfires and stalling).
Have done a temporary run of new fuel hose from the 'hockey stick' under the cab to the electric fuel pump (new).
The filters are between the new electric fuel pump and the carb, with all new hoses and clips.
This long rubber hose made no difference, so the old hardline is good.
The unions into the tank pickup look clean, and the pickup pipe isn't rotted.
As an example, yesterday I went for a 20 miles run, and it ran fine.
Got home with just over 1/2 showing.
When reversing back into it's space it gets tipped passenger side down on a hill, and it sputtered, backfired a few times and stalled. It then wouldn't start and kept back firing (still on the hill).
Pushed off the hill back onto the flat and it fired up fine and ran normally.
Can't think of anything I haven't checked for splits!!
Just after a couple of new ideas, as I can't track down my air leak.
'66 F100 with in cab gas tank.
When the tank is below 1/2, there starts to be a small amount of air getting into the fuel line. (Can see it bubbling in the filters, and get misfires and stalling).
Have done a temporary run of new fuel hose from the 'hockey stick' under the cab to the electric fuel pump (new).
The filters are between the new electric fuel pump and the carb, with all new hoses and clips.
This long rubber hose made no difference, so the old hardline is good.
The unions into the tank pickup look clean, and the pickup pipe isn't rotted.
As an example, yesterday I went for a 20 miles run, and it ran fine.
Got home with just over 1/2 showing.
When reversing back into it's space it gets tipped passenger side down on a hill, and it sputtered, backfired a few times and stalled. It then wouldn't start and kept back firing (still on the hill).
Pushed off the hill back onto the flat and it fired up fine and ran normally.
Can't think of anything I haven't checked for splits!!
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Just to be clear, all the rubber hose has been replaced to include the the short section under the drivers side cab, along the frame? Sure there aren't any pinholes in the pickup tube? Had the same problem in my '64, never did really determine what the fault was. It would shut down at half a tank like clockwork.
Posting Guru
Joined: Jan 2011
Posts: 1,670
Likes: 8
Small pin hole in the metal pick-up tube in the tank.
Here is how to locate hole in metal tube. Runs good till you reach a certain level of fuel and starts sucking air - right. If you have not yet put more fuel in the tank, remove the float assembly. Take a stick a couple feet long and slowly slide the stick into the tank till you reach the top of the fuel. You will most likely need a flashlight to see into the tank.That is also the depth on the metal pickup tube where the pin hole is. Sometimes it is hard to find a very tiny pin hole that is sucking huge amounts of air.
Here is how to locate hole in metal tube. Runs good till you reach a certain level of fuel and starts sucking air - right. If you have not yet put more fuel in the tank, remove the float assembly. Take a stick a couple feet long and slowly slide the stick into the tank till you reach the top of the fuel. You will most likely need a flashlight to see into the tank.That is also the depth on the metal pickup tube where the pin hole is. Sometimes it is hard to find a very tiny pin hole that is sucking huge amounts of air.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
That's a possibility, overall how do the tank innards look though? Ended up replacing the tank on my truck. I could have rigged something up but overall didn't want to make a career out of cleaning the old tank out and the rest of it. Tanks are tricky to work with, gasoline fumes are no joke
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Laughing Gas
Joined: Jul 2010
Posts: 1,121
Likes: 118
From: Chico, Ca.
Is pump below and as close to the tank as possible? Electric pumps are good pushers, but not good pullers.
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Posting Guru
Joined: Jan 2011
Posts: 1,670
Likes: 8
I remember some years back, someone was selling a thin walled plastic tube liner that would slide down into the existing pickup tube. Idea was, you remove the fuel line to the top of the tank, slide the liner in and replace the fuel line. The one end of the plastic tube had a flare to tighten up against the fuel line nut.
If you can find some thin walled tubing and you have access to a flaring tool, it might be worth a try for a short time fix.
At least you will know that a pln hole is indeed the problem.
If you can find some thin walled tubing and you have access to a flaring tool, it might be worth a try for a short time fix.
At least you will know that a pln hole is indeed the problem.
Logistics Pro
Joined: May 2015
Posts: 4,469
Likes: 965
From: Tri Cities, TN
Fuel pick-up
Pick-up tube is part of the tank. It's spot welded and soldered in. And from what I saw when I converted my entire fuel system to 3/8 inch lines. It was installed before the two halves of the tank were welded together. It was a lot of work for not much gain. If you want to go that way I can post more detail of how I did it.
Laughing Gas
Joined: May 2002
Posts: 873
Likes: 37
From: Ohio
Pick-up tube is part of the tank. It's spot welded and soldered in. And from what I saw when I converted my entire fuel system to 3/8 inch lines. It was installed before the two halves of the tank were welded together. It was a lot of work for not much gain. If you want to go that way I can post more detail of how I did it.
a while since I messed with it and my project has not gotten to the point of fuel system.
Posting Guru
Joined: Jan 2011
Posts: 1,670
Likes: 8
You might give this a try. Its made for those that wish to go to a modern fuel injection system but it also works with the stock fuel system. Just replace your stock float system with this one and cap off your original fuel pickup tube. PLUS, you get to run a larger fuel line to the motor. :O)
https://www.bobdrake.com/FordItem.as...b-566808f4ecf3
https://www.bobdrake.com/FordItem.as...b-566808f4ecf3
Thread Starter
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Freshman User
Joined: Oct 2015
Posts: 45
Likes: 0
From: Hampshire, UK
Hi all,
Thanks for the replies, and sorry for the delay.
Yes, All of the rubber has been replaced, including the short section under the cab.
This. I guess this means I don't know it is good afterall!
Anyone have any info on this? What diameter pipe should I be looking for?
I would like to prove it is the pickup pipe using this method before I go an import a new sender unit.
Cheers.
Thanks for the replies, and sorry for the delay.
Just to be clear, all the rubber hose has been replaced to include the the short section under the drivers side cab, along the frame? Sure there aren't any pinholes in the pickup tube? Had the same problem in my '64, never did really determine what the fault was. It would shut down at half a tank like clockwork.
Pick-up tube is part of the tank. It's spot welded and soldered in.
I remember some years back, someone was selling a thin walled plastic tube liner that would slide down into the existing pickup tube. Idea was, you remove the fuel line to the top of the tank, slide the liner in and replace the fuel line. The one end of the plastic tube had a flare to tighten up against the fuel line nut.
If you can find some thin walled tubing and you have access to a flaring tool, it might be worth a try for a short time fix.
At least you will know that a pln hole is indeed the problem.
If you can find some thin walled tubing and you have access to a flaring tool, it might be worth a try for a short time fix.
At least you will know that a pln hole is indeed the problem.
I would like to prove it is the pickup pipe using this method before I go an import a new sender unit.
Cheers.