How bad is it? Ran the truck out of fuel.

Running out of fuel does NOT ruin injectors. Trucks run out all the time and i've yet to hear any get new injectors. I've even done it myself twice. Right close to the pumps so all i had to do was pack some fuel to the truck. Slight squrt of starting fluid and i was running and rolling to the pump.

Your fuel gauge is usually in the drivers tank. There are hoses that run between the 2 tanks to keep the fuel equalized. Check to make sure the valve or both valves are open. TAnks come with vents so that they suck in air when the fuel drops. Otherwise you create a vacuum and the fuel stops flowing out. Possible for the return lines to plug also. One tank gets the return while the other gets nothing and runs out.

I'd check the valves to equalize the tanks. That's the most common problem. FL's have levers now. Above the batteries under the drivers door. But they seem to get disconnected a lot for some reason. You can flip either lever and run either side tank empty while the other tank stays full. It's possible the drivers tank might be partially closed.

I don't know what the other brand trucks would have.

 

You may be right, but during my 20+ years of wrenching you did NOT want to run a CAT C7/C9 out of fuel because it trashed them. Same goes for the Detroit DD series of engines, they can and will wipe injectors out when ran dry. Your mileage may vary.

 

I've only driven one cat engine. That was in a dump truck. The t600 had a d60. The FL had a dd15. Both those ran out in the parking lot so i didn't have to walk much to pack fuel to those.

I had a FL dump truck i coasted a few miles. Downhill. Don't remember what engine that thing had. It still ran 6 months later before being traded for a new pete dump truck. Same injectors.

I guess it's possible. But never happened with me.

 

You can check the vents easy .
When you stop at night just stick your tanks to see if they are level .
Now you just put your caps back on the tanks real loose . In the morning check each side to see if they are both the same level or real close if you are not on level ground .
If they are still way off then you might have a return line problem.

 

Some of you people are still living in the 70's. No modern truck I'm aware of has a fuel crossover. Last one I ever saw was on a mid 80's FLD120.

The fuel draw/return on many modern trucks works on a simple head pressure principle. Both tanks are draw, both tanks are return. The tank that has the most fuel will usually have more head pressure resulting in it supplying the most draw and receiving the least return. This is the reason a plugged up vent will cause a severe imbalance.

When a vent is restricted pressure builds up in that tank. Since the head pressure will be far greater than the opposite tank it will supply most of the fuel and receive very little return. Final result, one empty, and one half full.

 

#### it that's adding to your problems.

When you run out of fuel, you replace the filters always. always and always. Don't crank until you did.

 

Park my 07 w9 at an angle and the fuel goes to the lower tank. Filling up the lower tank and emptying the higher tank.

The 16FL i drove before coming home. Had valves to both tanks. Close one off and run off the other tank. Shut truck down for the night. Open closed valve and both tanks leveled out. The fuel gauge would be in a different position.

The vent is there to allow air in to the tank as the fuel goes down. Otherwise you create a vacuum.
Head pressure in a tank. Never heard of it. Crossovers DO exist. It's what keeps both tanks equalized.

Every truck I've been in has always had a hose running between both tanks.