My 1989 econoline with 5.0L and 185000 miles.
What are the best methods to repair, and seal, pin holes in metal fuel tanks? Hopefully there are some that don't require dropping the tank.

 

Most auto supply stores carry a "Fuel Tank Repair" kit.
Some consist of a crayon that you slide over the leak. It stops it ,so you can apply what appears to be a fuel resistant epoxy. I don't recall the brand name , but folks who reside in the salt belt become acquainted with these kits .

 

This is great! thank you for sharing this info with me! I will look at my local auto parts store soon for it!

 

Are the pin holes at the lower depression of the tank?

 

I have dealt with pinhole leaks, those "fixes" in the auto stores are temporary at best. I would change out the fuel tank with a new one. You are not likely to find a good one anymore from a boneyard.

 

To explain a little further, the kits that I have used contained the crayon, a fiberglass patch, the epoxy, sandpaper and a spreader..
Evidently it worked well enough that even after years of use ,the patch held up until I sold the vehicle . Never leaked , and even managed to forget the patch was even on there. I'm sure the condition of the tank and the quality of the job done had a lot to do with the result.
Used a lot of those kits when gasoline was harder to get and people were going around punching holes in tanks of parked vehicles just to get the gas inside. When you came to get your vehicle it would start and quit only to find your tank was empty..

 

Thank you!

 

No, the pin holes, start at, and are above the half way point of the tank, making it a poor idea to fully fill the tank.

 

You can probably fix them, but the metal may be bad enough to get more holes.