Fuel Tank & Pump

August 2019 Update

I completely redesigned the fuel system for my Pantera. Although what I had done below was a pretty slick set up, I didn't like how difficult it was to do maintenance to the fuel system. I decided to move things to where it is easier to access the various parts of the system. Please see my post on the Updated Fuel System here (https://johnspantera.blogspot.com/2019/08/updated-fuel-system.html).

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After a bunch of looking around and major amounts of sticker shock, I found that a stock tank just isn't in the cards for 3854. I then eliminated purchasing any kind of universal fuel cell for the car based on the limited space available to mount a tank. I decided to make my own.

I started by roughing out a general size for the tank using cardboard. I decided not to go crazy and make it fit every nook and cranny just to keep the number of bends and/or welds to a minimum. I could have really gone crazy and made a tank that would have fit like a glove. That would have added a ton more work and opened the door to more welds to spring leaks in the future.

After a bit of work I decided on a tank that is basically triangular in shape with the two sides measuring approximately 19" (next to the fire wall) by 17" (on the side next to the outside panel of the car) and 13" deep. This gave me a tank that will hold just about 13 gallons when completely full. I also decided to move the tank to the passenger side of the car to help distribute weight better from side to side. This was also a help since it was easier for the Coyote to have the radiator fill tank on the driver's side anyway.

I decided to make the tank out of stainless steel. I found a good sheet of 0.090" think stainless at the local scrap yard for a decent price. This is way thicker than is needed but, heck the added beefiness will add to the safety factor. The added thickness does add to the weight - it probably comes in at just around 50lbs. Next time, I'd probably shop around for something a bit thinner.

Once the general shape was cut out I welded it up. I left off the bottom off until I was able to sort out the baffle situation and cut the hole for the fuel pump. Here's some shots of the baffles going into place. You can see the shape of the tank.

You can see from the image above that a hole was cut in the top for the fuel pump. I decided to use the pump from the 2012 F150 that the Coyote engine came from. I located a pump assembly from our local salvage yards for just $125. It needed some modifications to help it fit properly.

I had to lengthen the pump assy to get it closer to the bottom of the tank. Ford made the pump in such a way that it is kind of universal. It was spring loaded to let you insert it into any size tank and it will collapse to the right height for the tank so that the pump will be close to the bottom. My tank was a little deeper than the design allowed for. If I left it like it was I would have 2 or so gallons at the bottom of the tank when my gauge would have read empty.

To make the changes I needed to extend the rods to make the pump touch as close to the bottom of the tank as possible. I added about 3" of stainless inserts into the rods to make the entire assembly longer. Here's a shot of the extensions.

Nothing fancy but it will get the job done. Next I had to extend the wires going from the connector to the fuel pump itself inside the assembly. I carefully removed the pins from the wires and soldered them up to new wires so I could reuse the connectors. The wires for the float on the fuel gauge didn't need to be extended.

I then put a little tack weld on the ends of the extension rods to hold them at the further's length possible. I didn't want it creeping back up to a shorter position making me get false readings on how empty the fuel tank was. Here's a shot of the finished assembly. You can see the blob of weld at the junction of the lower part of the pump assy and where the rod goes into the assy itself.

I then located the pump in the tank so that the float would work properly and made a six hole steel ring that would lock the pump into place. You can see pictures of this on the final shot of the tank itself further down in this post.

When I went to test the fit of the tank in the car I ended up needing to have to do some sheet metal changes on the car itself. The lip where the various body pieces come together on the top (behind the passenger back window) and on the frame piece just inside the rear quarter panel in front of the back wheel well had to be modified. I cut out about 1/2" off the top and took a hammer to bend down the body pieces on the frame. I welded everything up to give it a nice clean appearance.

With those mods the tank fit very nicely. I then went to work making some mounting brackets. The first one is for the bottom of the tank and sits on top of the cross member running diagonally from the outside rail to the inside rail. There is a hole there I used to locate the bracket and it gave me a nice mounting point to boot. Here's a couple shots showing that bracket.

You can see on the first shot the big nut welded on the bottom fits into the hold on the cross member. The two smaller side nuts will hold a long piece of threaded rod to lock the tank into position. The second shot is kind of dark but shows the bracket sitting on the cross member in the car.

The second bracket will to on top of the tank and bold into the bracing running just under the rear window cutout. This keeps the tank from shifting front to back. When it is all mounted in place for good I will line all the metal to metal surfaces with rubber to help keep it from squeaking. Here's a shot of the second bracket.

I will post more shots of the installed product when I have them.