How much fuel do you really have left when that fuel light comes on

The problem is. Diesels are not like carburated engines. If you run that engine to the point it gets air. You will need tools to purge the injectors of the air. You may end up being stuck along the side of the road because your too cheap to keep fuel in the tanks.

Lets say you did go on empty and you were able to have a switch to turn on more fuel. Like I said it isnt like carburated engines. To drive the truck long enough (presuming you only made 2 injectors air bound) is going to take away about 50% of the power. But trucks are not designed that way. There is no reserve need on a truck. Everyone else knows that you keep the fuel in it.

But hey, your on a tangeant. You go ahead and waste some ones truck for the experience. Yet just remember, if the company gets wind of you wanting to have an experiment on their equipment? It is their right to terminate your ability to work.

 

Just put a stick down in there and see.

 

There should be enough in there to make it to the side of the road when the truck stops running.

 

I run a daycab with a single 120 gallon tank. There's no idiot light on the fuel gauge to warm me I'm about to run out. But once the needle quits bouncing, I can go roughly 30 miles. The pickup tube must be pretty low on mine, I've already put 110 gallons in the tank and it still ran.

My very first time that I ran a trip with this truck that was long enough to even worry about fuel ended badly though. I was literally ten feet from our fuel pump when it died. Had to remove the filters and fill them to go ten feet and repeat the process after it died a second time. Oddly enough, I only put 100 gallons in that day. Tank holds 120. Guess it caught some air.

But really, there's no reason to test such things...

 

When i was doing 3rd party cement for schlumberger their trucks only had 1 100gal tank. We had a guy run out on the lease road and had to tow it the rest of the way to location. The needle was just a hair under a qtr. Prob sucked up air when fuel splashed back on a steep hill.

Fill the thing

 

The only way to find out, with your truck, is to fill it just after the light comes on.

 

And never trust the needle either

 

never let it go below a quarter tank.

and top off the DEF tank often. they like to suck trash from the bottom.

 

On my 2018 Cascadia with 140 gallon capacity, I have 35-40 gallons remaining.

I found resetting the fuel used/mileage counter each time I fuel gives me the most useful info. With my setup I can EASILY drive 700 miles if I can stand the fuel warning light in my face.

To reset it press & hold the + button, then press + again to confirm reset. My truck has a Trip counter & a Leg counter. I just use the Leg counter since I rarely start a trip with full tanks.