If you run out of fuel and can't put close to 35 gallons in it most likely there is a hole in the pickup tube in the tank module. This is much more common than you would think as the module is put together with sharp self tapping screws that can wear a hole though the tubing. What happens isn't that you run out of fuel but rather suck air that causes your pump to lose prime.
The first time I ran into this problem it really threw me for a loop, the truck was running out of fuel with half a tank (by the tank level, not the gauge). I have since run into three more trucks with this same problem. To buy the replacement part you have to buy the entire module, around $300. I haven't tried doing a cheap fix with just hose but guess it could be possible, the hose resembles coiled self storing air hose, not easy to find it diesel rated.

Good idea if you are ever in the tank to replace the level sender to grind the tips off the offending screws and inspect for any damage they might have caused. The screws are also known to wear a hole in the level float.

 

this is just a thought, but could the reason you were only able to put 29 gallons in it be because of how much diesel foams up when your pumping it????

i know if i let mine sit for a few minutes after the pumps' auto-shutoff i can usually get maybe 2 more gallons or so in it......

im not sure if this is a plausible situation or not, just somethin that crossed my mind

 

Thanks infidel I am sure that is my problem I am glad mine is only at the 1/4 tank and not the 1/2 like yours. $ 300 is worth the fix to me and I will grind of the tips of those screws.

 

Maybe you just have alot of sediment in your tank?? Crud and algae build up and over time maybe it has reduced your 34 gal tank to a 29 gal tank? I have only pulled one diesel tank, and that was a long time ago, but it was full of sediment and allege. Looks like pound scum or very short sea weed. They do make fuel additives to help in the area.

 

I have the same problem. The first time it happened I decided I was not watching the gauge, I only put in 29 gal. The second time I know I had enough, again 29 gal. I will pull it apart when I get some free time, but until then I am keeping it above 1/4.

 

Had this trouble with mine and found it to be my own fault as I had switched the supply and return hoses while replacing the rubber sections on my 12v.

 

Everyone really should keep the tank at least a quarter full all the time. Besides the fuel providing a heat sink to cool the fuel and as result keep the injection pump cooler as Shovelhead said the fuller the tank the less air that can condense and add water to your fuel. Most heavy equipment manufacturers recommend filling up before parking for the night for this very reason.

 

Has anyone actually measured the temperature of the return fuel from the Injector pump to confirm this, and if so, what were your findings?

 

How big are our tanks in our trucks. I never trusted my guage because it always gives me bad readings. Sometimes it could say I have half a tank left then when I shut it down and turn it on again it could say I have only 1/4 a tank left or less. So I always fill up when I get to about 1/4 a tank or more of fuel left and it only lets me put in about 21 gallons. Does that mean that when my gauge says I have a 1/4 of a tank left I really have around 10 gallons of fuel left? I'm just curious as to how much our trucks can hold and could I possibly have a smaller tank? Thanks

 

If you have a Short bed truck you have a 26or 28 gallon tank, If you have a long bed you have a 35 gallon tank.

 

If you get yours apart before I get mine apart let me know what you find please.

 

I measured the temp on the outside of the tank once with an infrared temp gun on a 20°F day. The full tank was 20° when I started out, 30 highway miles later it was 105°. When I returned, 60 miles total, the temp was up to 115°. I have feeling it probably wouldn't have gone much higher unless the tank was low.

 

How many gallons were in the tank at the highest temp? Thanks for the info, it's awesome!

 

Well I dropped my tank and replaced the Fuel Tank Module. Problem solved I drove around for about 10 minutes on about 1 gallon of diesel with no problems. The only thing I could see wrong with my old module is the strainer on the bottom of the module was caked up with gunk, there were no holes in the hose at all. I would think having the strainer full of stuff would make life hard on the lift pump but that is just a guess from me.