OK, starting a new thread here about my Aux fuel tank on my 66 f250. I can't seem to find any info on this particular one and I don't know if it is stock. So I appreciate any help. This tank is squarish on the bottom and has 2 bolts that appear to go through the tank and mount it. I have bypassed the tank fuel line switch right next to it, partly because i was told it is broken and partly because the interior tank needs to be drained and I need to do that later this weekend. Anyways, now we have a straight shot right to the fuel pump from the AUX tank. The Fuel guage only bumps up to the "empty" line on the guage. it moves for "all" the way over to "empty" but no more and I have put about gallons in the tank. I believe I also have the selector switch on the dash pointing toward the right (assuming it is in the correct position and not supposed to be up and down, there is no tank indicator on the switch). So #1) where is the fuel sending unit on this Aux tank? Do I need to drop the tank to get to it? Do I need to drain the tank (again, gads). And is there a chance the sending unit might just need a little float or something?
Oh and where do you buy an electric fuel valve and sending unit for the AUX tank?

After this I will need to clean the other tank because both tanks had old fuel when I picked this truck up last week. Just learning about this truck everyday!
man I love driving it. So glad I got it running, woo hoo.

 

Sorry, it's not "stock" ... it was added by a previous owner.

Here in CA, the Fey Bumper Co. installed individual and saddle tanks on these trucks for dealers and owners. The fuel cap is (usually) behind an aluminum door that is riveted to the bedside.

The tank(s) were mounted on the OUTSIDE of the frame rail(s), butted up against the bedside. Not a very safe arrangement that GM discovered when they did the same thing.

When 1970's Chevy/GM pickups were sideswiped or T-boned, the tanks split open, gas poured out and caught fire. Some people were burned to death. Not pleasant!

1967 was the first year FoMoCo offered an (optional 25 gallon) auxillary fuel tank...for Stylesides. The tank is mounted on the INSIDE of the left frame rail.

 

And the other choice is the tank mounted behind the seat, which is also comforting. hmmm.

 

I've never seen or heard of an in-cab tank being compromised in an accident. It is mounted up high on the floor pan, butts up against the rear body panel.

The problem with these tanks is their neoprene fuel filler hose. It is clamped to the filler pipe, to a raised round boss on the fuel tank.

The hose age cracks where the clamps attach, the hose also tends to swell up with age, causing cracks to develop. Both of these circumstances can/will cause fuel vapors to seep out.

So what do some peeps do, replace the hose? No, they install a 1965/68 or 1969/73 Mustang fuel tank, mount it under the bed adjacent to the rear axle. IMO, a real dumb idea, cuz they're unaware of what could occur.

The Mustang tank is constructed in two halves, when spot welded together, has a seam between the two halves that protrudes from the tank about 3/4 of an inch.

The same construction method was used for 1971/80 Pinto fuel tanks. When Pinto's were rear ended, the tank was pushed forward, the seam on the tank hit the center of the rear axle housing, causing it to split open.

Gas poured out, EXPLODED! This action also pulled the filler tube from the tank allowing more gas to pour out.

When this occurred, some peeps were trapped inside, 100's were burned to death! In 1975, the US Gov't issued the first recall ever, FoMoCo was forced to fix millions of them for free.

You wanna install a Mustang fuel tank under the bed? Go right on ahead, lotsa luck...but you've been forewarned. Not very comforting...is it?

 

I remember discussing this issue in depth when I was in engineering school many years ago. Apparently, Ford discovered the problem during crash testiing with a rear impact over 25 mph. The tank would get shoved into the differential and rupture. We were told that Ford came up with two potential solutions to the problem prior to the recall. One was a plastic baffle (~$8) that went between the tank and differential and the other was to put a rubber bladder in the tank (~$12). They chose not to fix the problem prior to the recall which in my mind was foolish. That cost could have been passed off to the consumer. Who would have noticed if the Pinto cost ~$12 more? I don't remember what the actual recall solution was, I am sure ND can fill us in on that.

 

The fixum kits (D5FZ-9B007-C & D) consisted of a longer fuel filler tube AND a curved plastic baffle that fit between the tank and the differentials center section.

The fixum kits prolly cost FoMoCo less than 10 bucks, but it cost them MILLIONS of bucks to fix all the Pinto's and Mercury Bobcats that were also afflicted with the same problemo. T'was a FIASCO!

The ill will cost FoMoCo millions of additional buckaroo's, due to lost sales. Peeps considered FoMoCo uncaring mucky-mucks...didn't give a damn about their customers health and well being, and before too long....

Along came the Firestone tire/Explorer FIASCO. Another occurred in the late 1970's with Firestone 500 tires installed on full sized Fords/Mercs & Lincolns. How many of y'all are aware of this FIASCO?!

 

I'm not but I would love to learn.

 

The first generation Mustangs through 1970 did not have an actual trunk floor. The top of the gas tank served as the trunk floor. I have a few Mustangs and it made me uneasy at first thinking that the passenger compartment could easily fill with gas in a major rear impact. That problem has never seemed to plague the Mustang though. I have seen hundreds in the salvage yards, many of which were destroyed by a major rear impact and i have never seen any evidence of one that caught on fire. The fact that it was a bigger car and the tank was farther from the differential probably made the difference. In any event, I don't worry about it now. Although I wouldn't put a Mustang tank in my truck for various reasons, it would probably be less likely to rupture in a truck with a solid frame vs a Pinto with unibody construction.

 

Re: the Aux tank: I'm assuming this fuel sending unit is toast, because the one in the "inside cab" tank was very corroded. I will probably order a new one from LMC. The inside tank was pretty rusty. I cleaned it out the best I could last weekend. (may need to order a new one, sigh) As far as the Aux tank, the sending unit is on top. I may need to go another route with the style of the unit since this is probably not the same as the stock tank. I was thinking maybe a Summit racing universal unit might work. Then again I might just disconnect this tank and run the internal cab tank only... after reading that side impact post...

 

Don't forget the Model T with the fuel tank on the firewall. Same issue.

Here is a shot of the aux tanks installed by the dealer in 1965. I removed them yesterday because I'm pulling the bed off to paint the frame and underside of the bed. These tanks are built like, well, tanks. Thick steel construction, not the thin stuff they make stock tanks from.

 

1908/27 Model T fuel tank is underneath the front seat, the cushion has to be removed to gain access to the fuel cap.

1928/31 Model A's have the fuel tank that butts up to the inside of the firewall. The exposed fuel cap is mounted at the center of the cowl panel.