Read your owners manual for your engine. It even says not to run below 1/4 tank if you dont desire air in the fuel system, or somthing along those lines.

 

Hence the harpoon mod

 

I must be, cuz I always fill up right at the last 1/4 mark. Never have and probably will never see the light, lol. Today, I put in 25.9 gallons and the needle was sitting right above the quarter line. I always figured with a 29 gallon tank each 1/4 would be ~7 gallons. My math must be really bad..

I think it depends a lot on the pump.

 

Or your gauge is was off...hah! :P

 

These gauges definately aren't perfect. When I fill up I'll drive more than 100 miles before it even moves. Then the first 1/4 tank gauge movement happens within 50 miles. Then slows again, then drops off quickly, finally resting at the bottom..... empty.

 

My 99 extended cab short bed only has a 19 gal tank. What was ford thinking?

BTW, my gauge must be screwed up because once I'm down to a quarter of a tank...I'm empty...yep, I ran her dry when I first got her. Any ideas what might be the problem?

 

2002 F250 Crew, 7.3L PSD Lariat, Short Bed, 118,000 miles, 2WD

My gauge will drop from Full to 3/4 after only about 50-75 miles, but I will end up getting 300 miles at just below the 1/4 mark where the light begins to come on. Definitely NOT a linear relationship!

Another thought here, guys, and this one has been really bugging me. (Please excuse the long post, but I believe that the detailed explanation is justified, so i ask you to be patient with me on this and think through my logic carefully.)

Several of you guys are saying that the foaming in the tank is what lies behind not being able to fill up completely, thereby justifying the Harpoon mod. This makes good sense and is rational, now that I know what the Harpoon mod is.

However, some of you are also saying that that is what lies behind incorrrectly calculated MPG numbers that are related to false LOW values. There is a problem with taking that position. It will be completely true for the FIRST fillup where the foaming limits the fill.

You have to remember, though, once you are in a cycle where the tank is not filled up completely due to this foaming (which I do not say is not happeneing, by the way), you are then "filling" to roughly the same false "full" level... as long as you're using the same fuel station, or same fill speed, tank after tank, which is what would lie behind creating the same amount of in-tank foaming. As long as you are then filling up to the same "false" full level, your MPG calculations will then be accurate from tank to tank.

The only potential flaw in what I've described will be if you are using different fuel stations and/or different filling "speeds", which would create varying degrees of foaming in the tank during fuel-ups, which would then result in different degrees of true "fullness" in the tank. At this point, what you would have would be varying degrees of accuracy in calculating your MPG values, and you would see inconsistent MPG values from tank-to-tank.

The only other problems with my assumptions here lie behind another assumption that teh degree of foaming is NOT affected by any of the following list of conditions:

-relative humidity
-ambient temperature
-amount/type of fuel additives
-amount of void space in the tank when filling up
-quality of diesel fuel
-driving habits/conditions (frequency & speed of accelerating/decelerating)
-general road conditions (steep hillls, sharp curves, rough raod surface)

OK... so what!!??

What I've personally observed in my own limited experience thus far (two months) is that my mileage on the last three tank fillups has been 13.0, 13.5, and 13.6. The region here is very hilly where I drive to work and back. Half of my driving distance (which is about 10 of a total of 20 minutes) is comprised of low speeds from 0-40 mph with multiple traffic stops/starts. I only have about 7 minutes of uninterrupted highway speed. This pattern is twice daily. On each of these fillups, I ran the tank one day past the fuel light indication, and filled up with 20-22 gallons, the last two fillups being nearly identical. I have used three different fuel stations, each of which is from a different fuel company.

I can therefore assume that I have a potential for a lot of fuel jostling in my tank, and that I probably beign to get intrained air near the end of my fuel run between fillups. I expect therefore, that the Hutch mod will be beneficial for me, and I will plan to do it. The Harpoon mod, though, seems to be a simple issue of convenience, only allowing me to gain a little more time between fillups by letting my fill up more completely. Regardless, if I ahve the tank down for the Hutch, it would be foolish to not go ahead and Harpoon it at the same time.

SOOOoooo....so what? I simply wanted to clarify that it is a bad logic that is based on inaccurate math to throw out a generic statement that in-tank foaming is repsonsible for low MPG calculations. It CAN be true, but will canNOT ALWAYS be true on every tank full of fuel. It CAN be responsible for some significant MPG variability from one fillup to another. Therefore, a more accurate statement would be that in-tank foaming that can occur during a fillup can result in INCONCSISTENT MPG calculations, and these inconsistencies can be LOW to varying degrees, but they will not ALWAYS be extremely low.

 

Not in my case. I fill up till it clicks off then squeeze in the last gallon and some change. I rock the truck so it burps and fill it till you rock it and it doesn't go down.

 

sounds like two good mods, so the harpoon mod is the cutting of the vent tubs in the tank. and can anyone verify if its easyer to just remove the bed rather then lowering the tank? dose anyone use these products?

airdog water/fuel/pump units?
http://www.itpdiesel.com/store.php?c...on=show_detail

or

http://www.dieselpp.com/

they both look like good units.

 

Well, it depends on your facility. If you have a shop setting, I'd remove the bed. If this is your garage, you might want to drop the tank

 

I go 150 miles before my needle starts to move. After that it will creep down to the F and once it is past that it goes quick.

 

My sister's Honda gets twice as many miles on the first half tank than the second half. So I guess it's not specific that one manufacturer has inaccurate fuel gauges.

 

i did a good top off one day, took forever, but i did get like 120 miles before i saw the gauge move off F. though if i dont take the time to top the tank off and just let it pump on full and click early, then i do about 50, 60 miles before it falls of the F on the gauge.

i think i read that u can get the hutch mod from an online web page some where? ITPdiesel.com?

 

The reason the gauge doesn't move much in the beginning is the marketing folks at Ford found out people pereceive their vehicle to be getting better mileage if the needle doesn't move much at first.

 

http://www.itpdiesel.com/store.php?crn=152

one of these days i am going to have to hutch and harpoon. I always stand around for an extra 5 mintues, after the click, slowly fillling the tank until I see the diesel.

F250-newbie, do you ever top off your tank? That you eliminate a lot of the foaming in mpg concerns.