With the 40 gallon XXL tank, it takes a little while to drop off full = from 894 miles to 800 miles, the gauge read around 15/16 with it not seeming to budge over the first 50-60 miles, but I think it just moves so little that it looks 100% Full. From 800 miles to 700 miles, I am a little below 7/8 full, so the % full is not tracking true, but as long as DTE is close and it zeroes in towards empty, this behavior doesn't bother me.One thing I have noticed with my 48-gallon Titan replacement tank is that it takes a long time for the fuel gauge to move off of Full, and it also drops fairly quickly when under 1/4 tank. I would be curious if those with the 40-gallon Titan have a similar experience. What I am saying is that it will not match your steady declining fuel gauge experience as you had with the OEM tank.
I usually can go through a tank pretty quickly but I shut down travel for work starting yesterday when I got home. It might be a bit to get through this tank.@Saathoff05 - I am seeing the same exact thing you are: After driving the DTE down to zero two-out-of-the-last-three fills, I have never gotten more than 34.5 gallons on any fill.
The question now becomes, how much of those 5.5 "reserve" gallons is really accessible/useable?
I would be interested in the results of your siphoning experiment if you find there is really 5.5 gallons left in the tank, because if so then I wonder if:
1.) The DTE is just off
2.) The Titan XXL tank is deeper than the stock tank and the factory sending unit/suction pickup is too short now and can't "reach" all of those 5.5 reserve gallons
If the latter, then I will tend to agree with you:
=> If the sending unit/pickup is not replaced, then I would hope for the price we paid that Titan designed the tank to have the same pickup height as the factory tank
=> I don't really want to test how far past 0 DTE miles we can go, as I don't think you ever want to run out of fuel with this or any other diesel engine
The new XXL tank is clearly ~3" deeper (why the factory shield can't go back on) but I didn't do my install, so I don't know if the hole where the sending unit goes is offset that same depth.
@kdjasper - what is your max gallon fill on the larger 48 gallon XXL tank for the 6.5' beds?
One thing I forget to mention... When I originally installed the tank I had an issue filling. Long story short, I had to remove the tank to find there was a plastic plug in to vent nipple. This was a stupid mistake on my part. There was a cover, which I removed when take was mounted and I hooked up the vent tube, but I missed there was also a plug.That's a real bummer you two aren't getting the full 40 gallons out of that tank! I'm interested in this product but not with that issue. I'm sure you'll let us know how it goes .. have y'all contacted Titan by chance? Interested to hear their thoughts as well.
My bet is this is a sending unit issue and you *probably* have another 5 gallons in the tank. If this is the ol' float on a rod technology maybe something as simple as bending the rod or replacing with a different rod will fix the issue. You may have to lower the actual sending unit though which isn't as easy. Unfortunately testing to see where the "missing" 5.5 gallons might be is not an easy quest to answer. I'd be hesitant before running her dry if that's what you're suggesting @Saathoff05, at least without being ready to prime the lines and bleed the air from them. Your fuel pump won't pump and your truck won't start when you fill her back up without doing that first!
I wonder that same thing. I have reached out to Titan to discuss. Hopefully they get back to me.Ohhhh, ok. I assumed like @jmperlik the fuel was there, the issue was either the DTE calculation or the ability to get at it ... but it sounds like the fuel just isn't there and in that case you're having issues maximizing the capacity of the tank. You said you filled her up as much as she would hold, until it was overfilling, but do you think the issue could be in that fill up? I attached the best picture I could find of the factory tank (maybe not exactly ours but hopefully close) and the 40 gal Titan. Comparing the two, it looks like some of the extra capacity is captured in two elevated areas separate from any vent where the factory tank is tapered from where the fuel goes in ... hmmmm
I had a jeep TJ that would puke gas out every dang time I filled up. Like, the handle would click and a quarter cup of gas would rush out and it had a little force to it. It's a known and fun little problem that was never addressed in any recall. I eventually replaced the filler hose with one that had a sort of oneway valve (out of a chevy) because Chrysler, in all their wisdom, couldn't manage that fix. Anyways, I figured the building vapor from the fuel entering the tank would shoot out once the tank was full. Point being, could vapor be building in those two pockets and prevent them from filling with fuel?? If true would constitute a design flaw to me but maybe you could wait a minute at fill up then rock the truck back and forth after you get the click and maybe jostle that vapor out of those pockets and get a little more fuel in? That could be totally wrong, just thinking outside the box here ..
I hope whatever the issue is you get it figured .. best of luck and let us know!!
The fuel pick up is at the bottom of the tank. Understood on your second point however I did have to take this tank out after initial install. I ran it down to empty to remove and there was not 5 gallons left. I am about empty now, I will put the truck on an incline and pump the tank to verify exact amount of fuel left at "DTE 0".Could it be just a case of the fuel pickup not being at the bottom of the tank ?
ie. the system (titan tank and factory fuel pump assembly) acting as if its empty when the fuel level drops below the point that the fuel pickup can access fuel... and there is still 5.5 Gallons left sloshing around that the pickup can't access ? it would act like a 34.5 gallon tank