cutting down a '90 F150 fuel tank, is it soldered?

[ladykiller]

I want to cut down a rear tank I got, and before I get started, does anyone know if the '90 F150 gas tanks are soldered around the lip?

[flyboy71]

Explain how you want to cut it exactly. Also, if its a used tank you dont want to cut or weld or anything that causes heat or sparks even if you know the tank is dry. Bad. Very bad.

[JMcTurnan]

I have no clue, but hes right. Drain it if anything is in there, than fill it with water to the top. Then dump it out, even the slightest fumes left in an enclosed area will leave you faceless.

[72Highboy]

Are you talking about where the filler neck hose attaches to the tank the little round tube sticking out?
If your talking about the flat lip around the whole tank its crimped and probably sealed with some type of adheasive.

Yes make sure you have all the left over gas residue cleaned out. Clean with anything that is not flameable.
I used to use soap and water to clean everthing out. But make sure before installation to clean all the water and soap out.

The couple tanks I had to weld in my FFA Ag class were two peices of metal top and bottom sealed, but I am pretty sure the little neck is welded. The only thing is your going to have to make sure your welds are covering the two peices of metal. Water test it to make sure. Try not to spot weld because that will leave little holes that will give you hell, try to run a nice bead all the way.

I wish I could help I love welding and putting my skills to the test.

[JMcTurnan]

Yes, you dont want it rusted LOL

[Dragon]

In the Military we would drain the tanks and then blow air into the tanks for 2 weeks if we were going to generate sparks repairing it or converting it to a baggage carrier for under the aircraft. If we had to open them in a hurry we filled them with water and used an air driven cutoff disc.

[convincor]

I want to cut down a rear tank I got, and before I get started, does anyone know if the '90 F150 gas tanks are soldered around the lip?

I guessing your talking about where the two halves of the tank are joined.
That is pinch welded. Like spot weld working with reistance, but thru rollers.

[fordman]

a custom tank may be easier to make than to cut and reweld a used tank. fill it with water at least.

[OldRedFord]

I dont like welding or cutting on tanks. /but filling with water, or purging with welding gas (like co2 or argon) is a good idea.

[Dragon]

Purging the tank with any gas takes days. the problem is not fuel sitting in the tank is is fuel embedded in the metal and slowly vaporizing.

[ladykiller]

The tank has been dry for about 5 months now. Good to know it's a pinch weld. I'm gonna initially give it a rough cut with a sawzall. Then I'll wipe, sand, scrub it clean, then chop it down, fit it, and weld. I just wanted to make sure that the seam around the edge could accept a weld. It'll be a while before I get around to it, so it'll be dry for even longer by the time I start cutting. I do appreciate the warnings. Maybe a safer plan will come up before it's time for the fuel system.

The reason: Right now, I plan on using an EFI engine, and I already have 4 EFI gas tanks with the appropriate fuel lines and pumps, none of which fit into the swb bump frame at their current size. I'll save hundreds of dollars by chopping a tank.

[fordman]

why not use the 1990 front tank instead? it will fit without any cutting.

[OldRedFord]

Purging the tank with any gas takes days. the problem is not fuel sitting in the tank is is fuel embedded in the metal and slowly vaporizing.

If you take a gas tank that has been sitting up since 1950 with no gas in it your still going to have that funk.

The only reason I would flood the tank with Co2 is to lower the oxygen content inside the tank to lesson the chance of a boom.

Tho I still would not weld on a tank.

[Dragon]

The tank has been dry for about 5 months now. Good to know it's a pinch weld. I'm gonna initially give it a rough cut with a sawzall. Then I'll wipe, sand, scrub it clean, then chop it down, fit it, and weld. I just wanted to make sure that the seam around the edge could accept a weld. It'll be a while before I get around to it, so it'll be dry for even longer by the time I start cutting. I do appreciate the warnings. Maybe a safer plan will come up before it's time for the fuel system.

Why not do the smoothest initial cut? Much easier to do that than mess with hours and hours of trimming. I own a Milwaukee V28 sawzall and I can cut fine smooth cuts. Just wrap a chalk line around the tank and snap it top and bottom. Then connect the dots on the side of the tank where the seam is.

The return line does not have to go to the tank it has to go to before the pump and have a check valve in it that prevents back flow to the engine, I already have a carb electric pump by my dual tank valve and that was where my main fuel lines will come together. and the return line will enter. I plan on two pumps and not using the floor valve.

[ladykiller]

I did consider using the midship tank. It fits awkwardly, so I want to get a trans in there before I decide to use it for sure.