My 1985 F250 4x4, who we will call "Chore Boy". In a real sketchy attempt up a hill in the woods(skidder trail), we lost traction a went careening backwards. Bounced off a couple of trees to end up piled on top of some stumps that were piled up on the sides of the trail.
Now my fuel tank is crushed. Nothing else is damaged. Maybe. Still in the woods.
Since this catastrophe has left me "tankless", I would like some input on fuel tank improvement mods.
What I am considering is the f26c rear tank with a no pump pick up/sending unit. Not worried about bed clearance too much at the moment because it has a flatbed that sits well above a factory bed, although I would like to change that, so I should take note of various tank configurations for future reference. Should I build a custom cell? I weld/fabricate in a fab shop sometimes when not doing other things. Don't want to spend a fortune but would like some improvement over the current 16gal midship tank that has a broken sending unit and is now caved in. Weight and center of gravity is a concern mainly because I put trucks in places they don't belong. This trucks purpose is as follows:
1. Transport me and my daily hand tool bags to the places the tools will be used. These places range from 500 mile round trip in a day retrieving equipment and other Craigslist type things to going to get a deer from the woods out in the back 40 at home, when driven daily it is loaded with 300-1000lbs and driven 100mi round trip.
2. Transport myself and whoever can fit on the bench seat, into the woods with saws and related gear for trail clearing/maintenance and firewood/sawtimber retrieval.
3. Needs to be able to transport myself and canoeing/camping/river gear into and more importantly out of the wilderness. And be capable of running as shuttle on the river.
4. I bought this truck for the same amount that I sold a homemade single axle lowboy trailer, which I had given up on being able to sell.
5. For about the same as what a decent 4x4 fourwheeler costs, this goes everywhere I need to go. And...drive to the beer store legally.

Anyway, thinking maybe just a new midship tank is the answer. I wonder if the later model plastic would be better for the whole no rust issue?

 

Replacement metal tanks are cheap. The factory had a skid plate system that covered the transfer case and both fuel tanks. Several of the trucks I have owned had the skid plate system, so it must be fairly common and may be easy to find in the junkyard.

 

Plastic Tank, Perhaps?

 

You can use the skid plates with the 38 gallon rear tank. Find skid plates and enjoy the extra fuel. Mine came with skid plates for both front and rear tanks. '86 Crew cab F-350 4x4. Not sure if they ever made a skid plate for the 16 gallon front, but you could probably modify the 19 gallon to fit.

 

I don't think I would go plastic if I was going to "off road" this truck.
Metal tanks most of the time will crush like what happened where a plastic tank could tear open.
With either type tank I would look into a skid plate.
Dave ----

 

I would get a big bronco tank and raise it up in the frame, being you have lots of up clearance due to flatbed. Put it in the rear between frame rails.
Or I have a square diesel saddle tank I welded skids on and slide it in my bed for extra fuel when towing. Could always mount a smaller rectangular one across front of flatbed.

 

If you live in an area where they use liquid deicer on the roads in winter I would consider going plastic with a skid plate. Those liquid salts are brutal on fuel tanks cause they get in between the straps and the tank where you can't wash them out. I don't think you have to worry about tearing a hole in a plastic tank. They are thick and pretty robust. Of course if you are of a mind to drive onto piles of stumps the skid plate would be a good idea.

If you don't live in saltlandia then get a cheap metal tank and keep on truckin...

 

Don't you think you would have the same issue with the plastic tank and metal straps or the skid plate?
A good drive thru car wash helps a lot on washing the under side of that crap.
I had a full size Blazer and during the winter I would run it thru once a week. After 16 years and 230K miles it was just starting to show some rust.
I was just tired of driving it and no AC in the summer.
Dave ----

 

The plastic tank I replaced my rear tank with with came with a lifetime guarantee against rust.

With a metal tank you need an isolation strip between the strap and the tank. Ford used a tar paper like fabric which absorbs moisture over time. You can't wash out any salt entrapped or absorbed into it or behind it. In ten 200 mile trips through liquid deicer treated roadway my rear tank developed considerable corrosion. In fact a hole developed in the tank itself right at the isolation strips. Since I had the skid plates holding in the tank and since they were quite thick I was able to wire wheel them and put several coats of enamel paint on them and reuse them with the plastic tank. Plastic tanks don't need isolation strips, so there's less chance of salts hiding in there.. I don't plan on rolling through anymore liquid deicer treated roadways...that's truck suicide for sure. But if one did do that, the plastic tank isn't going to rust out and the skid plates can be removed every few years and repainted.

There is a big difference between the damage done by liquid deicers and rock salt. Rock salt (NaCl) is not a problem for most well cared for and washed vehicles. Liquid deicer on the other hand is much more tenacious. When it dries the salt crystals (MgCl ) stick to everything. In fact washing after the crystals have formed will not "wash" them off...it reactivates them and more corrosion ensues.

On the mid ship tank, you'll have both the metal straps securing the tank and the separate (stock) skid plate. Plenty of room to wash and monitor the skid plate. There's an inch or so of clearance between them. The straps are accessible for washing too. With a metal tank and liquid deicers problems can and do develop. With Plastic the straps can corrode on you but to a lesser degree without the isolation strips. You can see if you have any problems. Also you can spray Fluid Film between the straps and the tank. Fluid film neutralizes salts, penetrates rust and prevents further rust and corrosion. If a strap goes bad it's almost certain you'll be replacing the steel tank too. With plastic only the strap will need to be replaced.

I still have a steel midship tank. The skid plate offered good protection from the road salts. Like I say it's easier than the rear tank to maintain...especially if you have the spare tire under there too! I spray Fluid Film all around the steel tank and the straps. That's about the best you can do.

Big Blue 2

 

I should add, the main reason I went with the plastic rear tank was that it was the only one I could find that was compatible with the skid plate support. I wanted to keep the skid plate and also the spare tire holder under the skid plate. All the rear steel replacement tanks I looked at were not compatible with skid plate support. For some reason they changed the size of the tank sump. Keep in mind that the thickness of a plastic tank will reduce the capacity of the tank. Most plastic ones were molded from OEM tanks...so the outside dimensions are the same as OEM. Mine was originally a 19 gallon tank...but the plastic one holds about 14 gallons.

Big Blue 2

 

Has anyone seen or Big Blue do you remember how the sending unit was retained in the plastic tank you can buy for these trucks? The reason I ask, I have a serious battle going on now with a plastic OEM tank in my 99 4dr Tahoe. A couple of months ago the tank started leaking on top. Pulled it down and it was leaking around the sending unit/pump.

Went to pull the sending unit out, the metal retaining ring was very rusted but more serious was the metal fingers that the retainer hooks too were rusted off. What they did, when they molded the tank they inbedded a metal ring in the plastic which is the same piece the metal retaining fingers are made onto. What caused it to leak more than anything, the metal ring rusting inside the plastic distorted the hole where the sending unit went, fouling the sealing area.

I tried rigging it with screws to retain it, but it is still leaking. Unfortunately, the 4dr tank is not made by the aftermarket, and it costs about $500 from GM, just because it's a 4dr. I am contemplating moving the spare tire, the 2dr tahoe tank has the same capacity and is just a little over $100.

 

The tank I got was an after market from MTS. The sending unit used the same type of gasket and locking ring that the steel tanks use. There was no metal ring embedded in the plastic tank. MTS thickens the area where the sending unit fits in and then they machine the plastic down flat around the hole for the sending unit. The gasket fits against that machined surface. Then install the sending unit directly on the gasket. The locking ring goes over sending unit and is held in place by screws and metal tabs that hold the locking ring in place. The screws are going into plastic so you have to install them properly and don't over tighten them. Use the specified number of turns the mfgr recommends after mating up.

No matter what kind of tank you have the area where the sending unit attaches to the tank is vulnerable to corrosion. The locking ring and the receiving tabs whether part of the steel tank or screwed down tabs in the plastic ones are vulnerable to corrosion from salts and moisture. The screw down tabs for the tank I used where zinc coated and the locking ring was also plated with a coating similar to metal tank locking rings. I took the opportunity to add several coats of enamel paint to the exposed metal parts including the sending unit itself. Then before installing the tank, and after the paint had cured for 14 days, I coated the exposed parts with Fluid Film. Hopefully it will last a long time.

Big Blue 2

 

Franklin, I took some pictures of my tank that shows the sending unit installation.

Top view shows opening for the sending unit with the rubber gasket laying in the hole. Note to the right the tabs sitting on cardboard receiving silver colored enamel paint and the vent holder in the filler neck I had to fabricate as this tank doesn't have that feature.



Tank ready to install. Even though I painted the screws with a bomb can after installing them it scratched up the paint on the screw heads so I dabbed on some more white enamel paint over the screws.

Anyway shows how this particular tank's sending unit was assembled.

Big Blue 2

 

So I decided to keep just a midship tank for now. I believe my tank was the 16gal? model. This truck is kinda pieced together by the PO, so I am going to focus on the engine and drivetrain mostly. The cab is rusted on the bottom pretty good, it has electronic stuff but most of it is inoperable.

I'm going with the MTS 4252A still need to source a new pickup/sending unit.

here's what it looks like

 

If anyone has a good part number for the fuel pickup/sending unit it would be appreciated. I believe it is the larger hole. I have not been able to source a MTS unit as of yet. But I think the MTS unit would be best.


I have a edelbrock 1405 600cfm manual choke, 1in riser, older offenhauser intake, efi manifolds, 3in thrush glasspack, walker ypipe 45166, Carter m4013 fuel pump, comp cams steel timing gears. I would like to go with a vacuum advance distributor, I'm trying to get rid of as much electronics as possible

Oh yeah, I replaced both motor mounts and transmission mount, new starter also.