FJ40 Rear Tank options w/ 4 link (1 Viewer)

[cseitz]

Is there anyone out there who is running a rear under mount tank with 4 link? I am trying to get the fuel tank out from under the passenger seat and relocate it. Just seeing if anyone has tackled this and if they would be willing to share their approach.

 

[SuperBuickGuy]

when I get there, I'll share it.... with that said, I know it's going to remove some floor space because if I drop below the frame I'll have issues with the rear pumpkin hitting the tank. What I am hoping is that the FItech I replaced the TBI with nets me better fuel economy which would reduce the fuel tank size requirement.

 

[cseitz]

when I get there, I'll share it.... with that said, I know it's going to remove some floor space because if I drop below the frame I'll have issues with the rear pumpkin hitting the tank. What I am hoping is that the FItech I replaced the TBI with nets me better fuel economy which would reduce the fuel tank size requirement.

Yeah I am in the same boat on fuel economy with my fairly stock ls, and automatic with overdrive, but pushing around 40's doesn't help fuel economy. I am just worried about getting a fuel level float in the tank if i keep it shallow. I'll have to see if there is options for that. keep me posted on your progress.

 

[SuperBuickGuy]

Yeah I am in the same boat on fuel economy with my fairly stock ls, and automatic with overdrive, but pushing around 40's doesn't help fuel economy. I am just worried about getting a fuel level float in the tank if i keep it shallow. I'll have to see if there is options for that. keep me posted on your progress.

I'm a huge believer in hydromat from Holley - it resolves the shallow issue by allowing every drop to be used.... as far as a gauge, that would be tough since there would be times where the float (no matter where it was) would be completely uncovered.... again, dual pickup and hydromat makes that issue less of an issue.

 

[cseitz]

I'm a huge believer in hydromat from Holley - it resolves the shallow issue by allowing every drop to be used.... as far as a gauge, that would be tough since there would be times where the float (no matter where it was) would be completely uncovered.... again, dual pickup and hydromat makes that issue less of an issue.

I'll have to do a little research into hydromat. It looks like foam is out according to the reviews I have read. I have located a couple of tanks through summit ~18gal which might be able to tuck tight enough under the rear of the cruiser ( might need to trim the rear body brace a bit). It looks like the tanks I have found though aren't baffled which worries me.

 

[SuperBuickGuy]

I'm using it in my FJ40 and also in my Corvette 'race' car. In my '40, I've filled at a gas station 15.75 gallons - it never stumbled.

 

[mano002]

I have a small tank behind my rear axle. It’s only ~7gallons, but I’m just going to use it as an aux tank. There isn’t much room with moving the 14bolt rear axle back

 

[cseitz]

I have a small tank behind my rear axle. It’s only ~7gallons, but I’m just going to use it as an aux tank. There isn’t much room with moving the 14bolt rear axle back View attachment 2119043

Its hard to tell, but is your rig on the ground in that big or up on a lift? Unfortunately my new cage isn't allowing for a tank under the seat, so I have to either get creating with a couple tank daisy chained together or try and stuff a decent size tank in the back. I picked up a 60's chevy car tank that is intended to be mounted under the rear trunk of the car. Its only about 7" deep. I might have to drop my bump stops down, but I'm going to start there. The tank is ~16 gallons. More to come.

 

[mano002]

it was on a lift at full droop.

I definitely had to work my seat frame around the factory tank.

Its hard to tell, but is your rig on the ground in that big or up on a lift? Unfortunately my new cage isn't allowing for a tank under the seat, so I have to either get creating with a couple tank daisy chained together or try and stuff a decent size tank in the back. I picked up a 60's chevy car tank that is intended to be mounted under the rear trunk of the car. Its only about 7" deep. I might have to drop my bump stops down, but I'm going to start there. The tank is ~16 gallons. More to come.

 

[cseitz]

it was on a lift at full droop.

I definitely had to work my seat frame around the factory tank.

My last cage allowed for the stock tank, but I had to build it pretty high to allow for headroom, I'm 6'2". I wanted to drop the entire height of the cage, so that meant shifting the seats down too. Give and take I guess.

 

[cseitz]

it was on a lift at full droop.

I definitely had to work my seat frame around the factory tank.

How much compression do you have on the rear at ride height?

 

[Mace]

The question becomes how far have you moved the rear axle back. If it's in the stock location, most aftermarket tanks will work just fine. If it's been moved back a lot, the space for a tank reduces significantly.

 

[mano002]

How much compression do you have on the rear at ride height?

There was ~6" of bump and 10" of droop with the 16" coilovers when I set it up last time. I do have to adjust a little for the final weight of the truck once its all finished.

And I agree with @Mace. My axle is as far back as possible while keeping the tire forward of the rear bumper. Its also only as deep as the rear bumper is tall, to not affect ground clearance, but my bumper isn't stock height either.

 

[cseitz]

I agree @Mace, axle location is critical. The back of my tires line up even with my rear bumper, so my axle it pretty far out there. I am leaning towards trying to recess a fuel cell in the bed area, without sacrificing all of my storage space, and possibilities of a back seat....