1973 F100 Trailer Special. I've got a pretty good gas leak, about a gallon every 3-4 hours. It's coming from a fitting just behind the drivers seat. A mechanic looked and said its a line that's cracked and I'll need to drop the aux tank to get to it. It appears to be between the frame and the aux tank. FWIW I don't use the aux tank. So it's only got gas in the main (rear) tank. Anyone have experience with this? Do I really need to drop that tank, and if so is that doable for a handy, but casual mechanic? I've worked on old cars before, and I have plenty of tools. Any tips or special tools I might need?

 

Tom, my 73 F-350 SCS has the same problem as your truck. Gas is leaking from somewhere up in the frame rail but is hidden from view by the AUX tank. I do not use the saddle tank and have recently gone through and repainted the tank and replaced all the filler and supply hoses that pertain to that tank. I do not know why it leaks gas there and I do not remember a rubber hose connection in the rear tank line in that location. I guess I will have to drop the front tank and see where the problem lies. Probably will get to that project in a month or so or when time allows. Hope you find your leak.

"bowties in the rearview mirror"

 

AFAIK, there is no such thing as a 1973/76 F100 Trailer Special. Most 1973/76 Trailer Specials were F350's on the 140" wheelbase.

No Ford truck came with saddle (R/L) tanks. Factory installed mid-ship and aft axle tanks are mounted on the left (drivers) side.

The mid-ship & aft axle tanks have a rubber filler hose that is clamped to the filler tube and the tank, includes a vent hose that was originally taped to the filler hose.

If the truck has Evaporative Emission, there's a fuel vapor valve on the top of the tank that uses a rubber gasket. The gasket age cracks/shrinks, allowing gas to seep out.

 

I was able to repair the leak for $7. I would have been less but I bought a couple extra feet of fuel line. There is about 3-4' of metal gas line coming from the rear tank, and another few feet of metal gas line that heads up to the carb. These two are connected with about 6" of rubber fuel hose, which was cracked.

It's a really tight fit for my big hands but I was able to just barely feel the rubber hose between the aux (front) tank and the frame rail. There's a J-shaped bolt on the fuel tank strap that hooks onto the frame, which had about 3" of bolt extending past the nut. I backed the nut off as far as I could without taking it completely off, gave the tank a wiggle, and it dropped down far enough for me to gain access to the leaking fuel line.

After that it was just a matter of replacing the hose.

For what it's worth, the truck is a 73 (June 73 to be exact) with matching VINs on the door and door frame, and unless someone replaced the badges on both sides, it's an F100 Trailer Special Ranger XLT.

 

Did you buy standard fuel line or fuel injector quality stuff? I hear that the fuel injector line will hold up over time better in the heat.

At least you got it fixed.

 

I'm sure it's standard fuel line. I just brought a piece of the old line into Autozone and told the clerk to give me 3' of the same stuff. But, yeah that's fixed. Now onto the water pump.

 

For what it's worth, the truck is a 73 (June 73 to be exact) with matching VINs on the door and door frame, and unless someone replaced the badges on both sides, it's an F100 Trailer Special Ranger XLT.[/quote]




Sounds like somebody changed the badges , ' NumberDummy ' knows his trucks. __





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