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  #1  
Old May 1st, 2007, 21:57
schmiedel's Avatar
schmiedel schmiedel is offline
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Question Fuel tank capacity mod

So, trying to do the following mod:

http://www.go.jeep-xj.info/HowtoFuelTank.htm

My fuel tank is a 15 gallon one, but I know for sure from the following post, gojeep's homepage and a picture I just took that the 15 gallon tank is nothing else but a limited 20 gallon tank.

http://www.naxja.org/forum/showthread.php?t=85716

Picture I took:



So, the small pipe that bends down on my tank should be bent up as much as possible to get gojeep's setup. Now the issue is I tried, really hard but as it can only be done with the force of the wrist, it's just not enough even to move the damn thing just a bit. I read on gojeep's page that someone had already bent the pipe up. ¿Any suggestions? I really hate the 15 gallon tank and getting between 20 and 23 gallons into the thing will just be really helpful.

Regards
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  #2  
Old May 1st, 2007, 22:04
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tgoff tgoff is offline
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Re: Fuel tank capacity mod

From reading GoJeep it looks like they cut it to make it shorter then added some extra hose. Maybe he'll chime in here.
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  #3  
Old May 1st, 2007, 22:10
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schmiedel schmiedel is offline
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Re: Fuel tank capacity mod

I hope he'll help. From his writeup, his tank is a 20 gallon tank, it's not cut off, the shorter vent tube is just the -only- difference between both tanks. I think if I make the mod, the fuel level won't be 100% precise in all moments, but I really don't care if it show up full for a long time as long as I can precisely know when it's going to be empty.

By the way, cutting of that tube wouldn't be easy at all, it's just not easy to get anything into the tank (my hands hurt a lot after having tried some things). I even managed to get a big wrensh in there (I attached a piece of rope to it so I could manage to get it out again), but it's just way too hard to just bend it.

Regard

Last edited by schmiedel; May 1st, 2007 at 22:13.
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  #4  
Old May 1st, 2007, 22:14
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Blaine B. Blaine B. is offline
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Re: Fuel tank capacity mod

Really, that's interesting.

So what's the point of limiting the 20 gallon tank?

Is it a ripoff? Just a reason to charge you extra when there's very little difference between the differently sized tanks?
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  #5  
Old May 1st, 2007, 22:22
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schmiedel schmiedel is offline
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Re: Fuel tank capacity mod

Blaine, it really seems as a cheap way to get to charge extra money (remember Intel burning out cache from Pentiums to sell Celerons). This is a quite common practice, but we won't know until I find the way to get the proper setup and try it out. Then I'll gladly report the amount of fuel I can get into the tank...

Regards
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  #6  
Old May 1st, 2007, 23:24
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Blaine B. Blaine B. is offline
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Re: Fuel tank capacity mod

That's just plain evil and stupid!
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  #7  
Old May 2nd, 2007, 00:42
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Gojeep Gojeep is offline
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Re: Fuel tank capacity mod

Have you tried sliding some tube over the vent to give you the leverage needed to bend it up? The longer you can fit on the easier it will be. Mine is not like that to start with so can only give suggestions.
From memory the YJ's also had the same tank size for two different capacities, but a lower vent so you could not fit in as much as well if you didn't pay for the extra capacity.
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  #8  
Old May 2nd, 2007, 06:54
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schmiedel schmiedel is offline
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Re: Fuel tank capacity mod

Mmm, the tube idea doesn't sound bad, don't know why I didn't try it out yesterday. The only problem will be that I won't be able to bend it up as much as I want to.

I could try something like the following:



But I'm concerned about the fuel that will accumulate in the lower section. Won't this cause an empty tank not to fill at all because the vent tube isn't empty?

Regards
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  #9  
Old May 2nd, 2007, 07:05
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schmiedel schmiedel is offline
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Re: Fuel tank capacity mod

One more issue; I remember having seen the sender unit like bent down; I have been searching for sender units and I think the 15 gallon tank sender is different than the 20 gallon tank one; here's the difference I think I've found:



Anyone can confirm this?

Regards
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  #10  
Old May 2nd, 2007, 09:50
John90XJ John90XJ is offline
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Re: Fuel tank capacity mod

Could you get a small pipe cutter in there?

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  #11  
Old May 2nd, 2007, 09:57
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schmiedel schmiedel is offline
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Re: Fuel tank capacity mod

Maybe it would be possible, but I would preffer to bend the tube up, however if it's not possible, I could try out with the cutter; I just will have to attach it to a piece of rope so when it falls into the tank it can be recovered easily. I'll go to a tubing store and ask for it, if it's cheap I'll buy it and give it a try.
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  #12  
Old May 2nd, 2007, 14:36
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schmiedel schmiedel is offline
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Re: Fuel tank capacity mod

Last update:

I made my first approach to modification, and I managed to get 6 more gallons into the tank than I normally can, so it's a big improvement; I'm not sure if I could have gotten more into it, but as a first approach it's a huge difference. I also flattened the bends on the sender so it behaves like one from a 20 gallon tank, that also worked fine, I left it working and it showed full just a a moment earlier than the pump stopped. So it means that at least I gained something.

As I didn't drop the tank, I'm not sure if I got the optimum result, but at least it helped me alot; now my fuel pump sounds a bit, so I'm considering in buying a new one and carry it with me in case the old one fails; maybe some day I might drop the tank and make a better setup.

Now my question is, I did the setup with pvc tubing; I wasn't sure it's the right setup, but I found some info on the net on pvc fuel lines, so I'll try it out; the worst that can happen is that it falls apart.

Here's the picture of the final setup; it's blurred but it's the only one I took (I was in a hurry):



And when I filled the tank:



So, I'll monitor it and see how it behaves.
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  #13  
Old May 2nd, 2007, 15:09
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WheelinJR WheelinJR is offline
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Re: Fuel tank capacity mod

So that's why I was able to very slowly once get 17 gallons in my 15 gallon tank...

Very interesting. I might have to tinker with this someday. Would be very useful in our rigs for the rallies.

Was it like this in most years? say older 88-89 renix's and newer 91ish HO's ??
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  #14  
Old May 2nd, 2007, 16:13
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techno1154 techno1154 is offline
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Re: Fuel tank capacity mod

That tube in the tank is put there as an anti-pollution device. It essentially limits the amount of gas in the tank and maintain a sufficient air space that allows for expansion of the gas on a hot day without it overflowing and spilling on the ground there by causing polution and a potentially dangerous situation lik a fire risk ect;ect;ect.
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  #15  
Old May 2nd, 2007, 16:14
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cumorglas cumorglas is offline
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Re: Fuel tank capacity mod

Quote:
Originally Posted by schmiedel
I really hate the 15 gallon tank and getting between 20 and 23 gallons into the thing will just be really helpful.

Regards
I did this mod to my 86 four cyl 12 years ago. was able to put 22 gallons of fuel in. at the time i was getting 23 mpg on the highway. could drive from buffalo to lansing and gas up when i got there.

replaced the tank in my 89 4.0 las spring and forgot to do the mod. been to lazy to take it back out and fix it
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