Anecdotal information (RotoPax 4 Gallons)

[uplandgunner]

Post 57 shows why I don't like that rack. The rollup tonneau isn't so rollup. There is another thread where someone else cobbled something together with bits and pieces from several places and it works great with the OEM tonneau. No need to jerk it all around--just roll it up naturally. So, I'm thinking more like this ...

https://www.jeepgladiatorforum.com/...dea-of-a-perfect-for-me-gladiator-rack.27705/

Well after looking at ideas and thinking this through, it seems simplest to just go with the Max Mod rack and fab a spacer to go in between the two parts of the tonneau bracket. If you get my idea of what I'm talking about.

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[Godfadr]

Specs say 22 gallon tank, but I go from top off to empty and warning lights buzzing I am low range and fill up and its only 18.5 to fill up.

They are sandbagging a lot of fuel. One of these days I am going to run in empty to see how much...really.

 

[ACAD_Cowboy]

They are sandbagging a lot of fuel. One of these days I am going to run in empty to see how much...really.

I've been saying I'm going to run that test for that last 5 years. In my case the tank is listed as 22.5 and the deepest ive ever run it is ~20. The bigger issue is the pump is fuel cooled so this test has some concerns.

Im thinking the better way would be to drop the tank, drain and refill from scratch with a funnel and cans.

 

[Gatorized]

I've been saying I'm going to run that test for that last 5 years. In my case the tank is listed as 22.5 and the deepest ive ever run it is ~20. The bigger issue is the pump is fuel cooled so this test has some concerns.

Im thinking the better way would be to drop the tank, drain and refill from scratch with a funnel and cans.

Just get a transfer pump, 4 - 5 gallon gas cans plus a 3 gallon can then fill the tank and pump it all out .

 

[ucijeepguy]

I've been saying I'm going to run that test for that last 5 years. In my case the tank is listed as 22.5 and the deepest ive ever run it is ~20. The bigger issue is the pump is fuel cooled so this test has some concerns.

Im thinking the better way would be to drop the tank, drain and refill from scratch with a funnel and cans.

How is that different from any other fuel cooled pump in most other vehicles? It's not, there are millions of vehicles on the road that use a similar pump system. They screwed up the gauging system on the fuel tank. It doesn't make any sense to leave 4 gallons of fuel unusable, or unmeasurable.

 

[ACAD_Cowboy]

It's there and usable but a 4 gallon reserve is huge. I've always shied away from running a fuel cooled (and lubricated) pump that low as you can kill it.

As for the gauging, all we have is the dash gauge showing relative fuel on board and the range to empty. What we are missing is the absolute fuel level as measured by the float, X liters to dry.

Now looking at the numbers my 22.5 gallon tank has a rough floor surface area of 62"x14" which at 1" of fuel depth yeilds 3.75 gallons of fuel which breaks out to 22.5 gallons at 6". Accounting for the pump, baffles and design safety this all tracks.

The low fuel indicator is going to trigger with enough lead to allow you ~50 miles to find fuel and not endanger the operation of the pump. They know that the pump needs to be cooled and lubricated and they know that the bottom of the tank is where the dregs are, all that dust and crud and water that will accumulate. So is 4 gallons good? Whos to say but 10 more gallons from your onboard carry is going to get you a lot further on down the road.

 

[ucijeepguy]

All that really means is we really only have a usable 18 gallon tank. I had longer range on my V8 Ram.

 

[ACAD_Cowboy]

No you can use all 22ish gallons if you want to its not like it hits 18 and the truck shuts down.

The question is how deep to you want to go into the reserve. I have no idea the shape of the well the pump sits in so i cant tell you yeah you can use all of it because the pump is in a well with a surplus gallon thats not part of the stated capacity

 

[Gray_Bison]

Query - how is 4 gallons equate to 1/4 of tank of fuel when a JT fuel tank is over 20 gallons?
5 gallons is less than 1/4 of a JT fuel tank.

All I can tell you is that I had 1/4 tank of fuel in the JT. I added the 4gal Rotopax into the tank, then the gauge reported I had a 1/2 tank. I make no claims to 100% accuracy, it was just an anecdotal observation. Nothing scientific to report here.

I bet if you do that twice, add 4 gal from 1/4 to get to 1/2, then add another 4 gal it won't quite make the 3/4 mark. If the JT tanks are anything like the tanks on my GM trucks, the top 1/2 is "bigger" than the bottom 1/2. I learned that early on when I was getting 250 miles from full to 1/2, then only 150-175 from 1/2 to low fuel.

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