School me on aux tank plumbing (1 Viewer)

[ducktapeguy]

When I installed my tank, I just cut a hole with a hole saw for the sending unit, then drilled and tapped the holes for the screws. It's not rocket science, but it is a little nerve racking to be drilling a huge hole in your tank. No problems with leaks so far. Just try and position the float near the center of the tank so you can get more accurate fuel readings.

That hole looks like 1/4" npt, they sell 90 degree adapater fittings to convert to compression fittings or flare fittings. I thought about running metal fuel line parallel to the existing fuel line on the outside, but because of where my pickup tube was located (inside the frame rail) I wouldn't be able to access it. Instead, I just used 3/8" hose all the way to the pump and ran it inside the frame rail. For those fuel line clamps, look at some of the hot-rodding places, they sell some nice aluminum clamps specifically for fuel line.

BTW, your hose looks like it cracking already.

 

[FishNinJay]

When I installed my tank, I just cut a hole with a hole saw for the sending unit, then drilled and tapped the holes for the screws. It's not rocket science, but it is a little nerve racking to be drilling a huge hole in your tank. No problems with leaks so far. Just try and position the float near the center of the tank so you can get more accurate fuel readings.

That hole looks like 1/4" npt, they sell 90 degree adapater fittings to convert to compression fittings or flare fittings. I thought about running metal fuel line parallel to the existing fuel line on the outside, but because of where my pickup tube was located (inside the frame rail) I wouldn't be able to access it. Instead, I just used 3/8" hose all the way to the pump and ran it inside the frame rail. For those fuel line clamps, look at some of the hot-rodding places, they sell some nice aluminum clamps specifically for fuel line.

BTW, your hose looks like it cracking already.

Thanks DuckTape,
There's a hotrod auto shop near my place. Great idea!!

Drilling the hole seems easy, but I guess I'm wondering how much of a problem these leaking gaskets are? Is there anything you can put on the gasket/flange to prevent leaking? What about the screws? Can I use "self-tapping" or do I need to drill and tap holes? Sorry if it's a question.. just not something I've ever done. But, it looks easy enough on YouTube!

The tank itself seems well-made and not leaking at all.. i'd hate to mess that up just to put in a sender.

Yeah, the hose looks bad.

Was considering metal line because of the cracking hose you pointed out, and this gas leak in the line. I'm going to replace the whole run of fuel line.. just need to decide rubber vs metal. Right now, much of this rear line from the aux tank is alongside the frame. Other areas, it runs inside the frame rail. Thanks for the tips and advice. Keep them coming please!!

 

[bikersmurf]

I'd still run a stock sender with your 7" deep tank.

I see two options:
1) You can bend the rod so that it doesn't sit on the bottom of the tank and the tank will read 3/4 full when the tank is full.
2) Shorten the rod so the range of the float matches the depth of the tank.


I'd position the sender towards the center of the tank ie. more like the rear most option. Keep in mind internal baffles in the tank and space for the sender and wiring above the tank.

I looked inside the tank with a flashlight to see where the baffles were. If in doubt probe around with a long wire.

 

[imabigbangkindaguy]

Hey Arc1, post up some good pics of your tank straps. All the others I have seen run front to back, not side to side. Looks interesting. While we are on it, The tank I have has 4 holes through it, where the previous owner had it "secured" with bolts to through the tub floor. Is this the best idea, or should I go with the some fabricated tank straps?

 

[ducktapeguy]

I wouldn't be worried too much about leaking from the fuel sending unit. After all, the stock fuel tank uses the same sending unit setup inside the cab, so if there were problems you'd hear a lot about it. I did smear a thin layer of sealant on the gasket and screw holes before mounting, and haven't had any problems with leaks.

I drilled and tapped the holes on mine, I don't trust the self tapping screws too much, plus I already had the correct size screws from my old sending unit. I was going to cannibalize the mounting ring from my old gas tank and weld it onto my auxillary one, but the tank itself was thick enough to tap some threads. I'm assuming your aluminum tank is even thicker than the steel versions, so the threads would be better. I ran all rubber fuel hose like because I didn't have much choice like I said, but even if I didn't have that problem I probably wouldn't have run all metal lines anyway. Maybe one long straight metal line along the frame rail where it's protected, but the connections to the tank and fuel pump (or switching valve) would be rubber to isolate the line from vibrations, and to make installation and removal easier.

IABBKG,

I had 3 holes going through the tank secured with 3 very long bolts through the tub similar to yours. I didn't use that setup because the idea of hanging a couple hundred pounds of fuel from the sheet metal tub on washboard roads didn't inspire confidence. I tried fabricating some 1/8" x 2" straps front to back to hold it, but that didn't secure my tank well enough side to side, it was able to slide left/right because it's narrower than the frame by a few inches. What I did was weld 3 pieces of angle iron to the tank to secure it directly to the round cross member and the angled frame supports in the rear. I still have straps to back it up just in case of failure.

 

[bikersmurf]

My tank has two long bolts going through it to mount it. I'm going to use them as my floor is thicker than the frame . An 1/8"+ thick floor also makes for good weight distribution .

 

[73fj40lc]

Definatly go with metal fuel line. Most newer vehicles have metal lines because of the ethanol that is used in most gas these days. The ethanol will cause most rubber lines to dry out and crack very quickly. I have had to replace rubber fuel lines on my 40 several times. I have Goodyear rubber fuel lines in now that are supposed to handle the ethanol better. I am eventually going to go with metal as much as possible.

 

[FishNinJay]

Definatly go with metal fuel line.
>>snip<< I am eventually going to go with metal as much as possible.

I really like DuckTape's idea.. using metal line except at fixed points. I have several, like at the fuel switch, aux tank, etc.. Also, a few places where the line goes into and out of the frame rail. I know these rigs are like tanks, but I was wondering if I went all-metal and got rear ended, would that impact transmit all the way along the line and **** up every fixed point all the way to my fuel pump & carb!? (yes, I really am that paranoid and think of these crazy things )

I'll look into the Goodyear hose for my transition points. What's so special about them?

Going to go visit my rig now. Will take pics of the aux tank straps.

 

[FishNinJay]

Hey Arc1, post up some good pics of your tank straps. All the others I have seen run front to back, not side to side. Looks interesting. While we are on it, The tank I have has 4 holes through it, where the previous owner had it "secured" with bolts to through the tub floor. Is this the best idea, or should I go with the some fabricated tank straps?

Not great pics, but hopefully what you are interested in. The overview pic, I've posted twice already in this thread above.
Here are some close-ups of the straps and bolts.

 

[imabigbangkindaguy]

thanks for the pics.

Wow, that looks to be just bent flat stock, pretty simple, I hade a much more complicated scenario in my head. But I guess it's true what they say, Keep It Simple Stupid...

 

[FishNinJay]

thanks for the pics.

Wow, that looks to be just bent flat stock, pretty simple, I hade a much more complicated scenario in my head. But I guess it's true what they say, Keep It Simple Stupid...

yeah, reading your guys' posts, I'm getting paranoid about the weight of this thing once I fill it. I peered around and over the tank best I could, and don't see anything else obvious like any mounting bolts or tabs. I think these straps are it. Any concerns? While it's dropped, I could probably make some simple mods if necessary.

 

[imabigbangkindaguy]

Looks fine to me, a full tank wieghs about 160 lbs, so not alot of weight by any means for iron stock, or descent hardware. I think the main concern would be if the tank was not tightly secured under the bed, with the ability to move and jiggle around. The guy I bought my tank from had it secured with 4 carriage bolts and washers, and he said he was never in fear of it dropping, I imagine your straps are more than adequate, I think I will make up some of my own, I'll take some pics of the process. I will let ya know when the tank falls out in the middle of the road...

 

[GREEKMEAT]

FJ40/T1 fuel system ?

On another note, I am installing a 93 T1 350, which is TPI, in my 76 FJ40, and I think that the el cheapo replacement plastic tank is not going to be abe to hande my fuel requirements. So I am looking into an aux. tank/or for it too be my main tank. Any recomendations out there ? Is the LT1 fuel system pressurized , as in not vented ? I have a nice Aeromotive fuel pump, and filter, will I need a pres. regulator also ? Thanx, George.

 

[jonah]

pix of prototype

10 in deep 16 long and 32 wide do you all think this will fly after rerouting exhaust it fits in nice i do plan to cover it with a skid plate. i have no clue how much it will hold .

 

[bikersmurf]

Can't see the pics

10x16x32 should work fine. Did you factor in a step in the top to clear the reinforcement that goes across the bottom of the body tub?
I'd also slope the back edge to improve the departure angle as is done on some of the newer tanks.

 

[Volcano cruiser]

Guys,
I´m installing an aux tank set up as well with the Pollack switch. I´m having a a set of new pick up and return tubes made with a new sender unit and float. Does anyone have the ohm range of the OEM fuel sender unit? Thanks.

John

 

[bikersmurf]

Guys,
I´m installing an aux tank set up as well with the Pollack switch. I´m having a a set of new pick up and return tubes made with a new sender unit and float. Does anyone have the ohm range of the OEM fuel sender unit? Thanks.

John

https://forum.ih8mud.com/40-55-series-tech/267066-where-put-fuel-sender-maf-aux-tank.html

Post #7 has some answers that you're looking for.

 

[Volcano cruiser]

https://forum.ih8mud.com/40-55-series-tech/267066-where-put-fuel-sender-maf-aux-tank.html

Post #7 has some answers that you're looking for.

Dude,
I read that thread and I read right past that EXACTLY what I was looking for. Thanks!!!

 

[bikersmurf]

I installed a stock, unmodified, sender into my tank following those instructions. The tank is still on a shelf so I don't know how well it'll work, but it should work fine.

Some extend the sender, however, I didn't see the need. I'd rather fill it when it hits E even if that means I have a few extra galons sloshing around the bottom of the tank. Also, if I keep both tanks I can run it dry if I really need the range.







Anything beats having no gauge.

 

[Volcano cruiser]

I installed a stock, unmodified, sender into my tank following those instructions. The tank is still on a shelf so I don't know how well it'll work, but it should work fine.

Some extend the sender, however, I didn't see the need. I'd rather fill it when it hits E even if that means I have a few extra galons sloshing around the bottom of the tank. Also, if I keep both tanks I can run it dry if I really need the range.
Anything beats having no gauge.

In my case I found the tank, same size and config as an S10 tank but with no sender. I looked for weeks and tried maybe a hundred units out but no go., has a 9 screw pattern. I thought that I was screwed on the tank until I remembered that I had talked to a guy in upstate NY who makes custom senders and repairs them. I talked to him and I had a machine shop make a plate with the same 9 screw pattern and he will make the float and two fuel tubes to fit the dimensions of this tank exactly, no guess work. The only thing that he wasn´t sure of was the ohm range for the sender. He had notes from a job he did some years ago but on an earlier year cruiser, like 63 or 66. Rather than fab something with the wrong values he asked me to find out as I speak to you guys and he doesn´t. This info completes things. Thanks again, this is a huge help.
John