Piecing Together An Aux Fuel Tank Setup

Like. Didn't see CEL mentioned before this, what are you getting? My guess would be something with the evap circuit, charcoal filter, fuel cap etc.

 

I haven't gotten any CELs yet, but that's what I'm worried about. I'm hoping the check valve in the fuel pump will take care of it. If not, I'll put the solenoid valve back in.

 

In 1999 I bought a used '97 4WD Dakota that had a 20 or 25 gallon owner installed home brewed auxiliary fuel tank in the bed. There was no transfer switch, no pump, no valve, no wiring, no nothing. It just sat there with a fill neck sticking out over the bedside and what looked like a plain old drop tube through the bed into the top of stock fuel tank. I didn't use the aux tank for a couple of years because I was afraid that when I filled it fuel would just pour out of the stock fill tube. Looked to me like the previous owner didn't have a clue what he was doing. I finally nutted up when it was time to take my first 1,100 mile trip and filled the tank. Nothing came out of the stock fill tube and the gauge stayed on full until over twenty gallons of fuel had been burned. To this day I have no idea how it worked. Like a damn magic trick. And I couldn't ask the old boy that built it because I had bought the truck from his estate. I would really like to know how it worked and I'm pissed at myself for having been too damn lazy to tear it down and take a look.

 

Cant explain the vent lines but I know the fuel neck & cap are designed to be fume & spill proof in case of a roll over accident. Back then maybe the evap venting wasn't what it is now, but that is certainly interesting!

 

Parts list to come.

 

IM- incoming (so we don't clutter the thread).
*Edit
Your auxiliary tank likely worked by gravity, the same as the one we bought from Downey Toyota and installed in our 1988 Toyota.
Think of the way an automatic dog water dish works. You know the ones that you place a 2 litre pop bottle on upside down and as the dog drinks the water in the bottle replenishes.

Our Aux tank had a 'drain fitting in the lower drivers side corner and a rubber hose that went to a 90* fitting that replaced the drain plug on the bottom of the OEM tank. Fitting could not have extended more than 1/2" up from the bottom of the tank. All the venting was spliced into the oem tanks evap system. As the fuel weight went down in the OEM tank fuel from the aux tank would automatically replace it until the aux tank was emptied and that is when the fuel gauge would be working closer to normal.

We would fill the OEM tank first until it was full and then fill the aux tank. Our fuel gauge was similar to how yours worked- would stay full for a lot of miles and then eventually start to go as it did before the aux tank.

Here is the thread I made about doing a 2nd gen aux tank (won't be getting to it anytime soon.);
https://www.tacomaworld.com/threads/auxiliary-17-gallon-fuel-tank-idea.477475/

 

It's all good. I'm curious too.

 

Looks great Tim!

 

@Wheelspinner Parts breakdown added to OP. How'd I do?

 

Nicely done OP.

 

Put a 45* filler on today. Should make things a little easier.

 

Have you tried it out yet?

 

Yup. Works great. I ran a couple of tanks through it. No CELs so far. It was just a PIA to get the tank full with the flush fill. Should be better now.

 

Awesome

 

Nice work!

Have you figured out your max range, loaded with the trailer yet?

 

Thanks Mojo.

I have not. I'm steeling myself for the let down... lol

 

Thank you for this write up. I'm going to go this route with mine too. Any recommendations for me before i start a similar build?

 

I can't really think of anything that's not in the OP.

Good luck with the install

 

I hate to necro threads like this, but I was wondering if you had any results to report about max range and such for us?