Out of Fuel: What It Costs Beyond the Fuel

Running out of fuel in a gasoline vehicle means adding fuel and turning the key. In a diesel it frequently means more than that, because air gets into a system that does not tolerate air.

Here is what actually happens and what it takes to get moving.

Why diesels are different

A diesel injection system needs fuel with no air in it to build the pressures it works at. When the tank runs dry, air is drawn through the whole supply side — lines, filters, pump.

Adding fuel does not push that air out. The system generally has to be primed and bled before it will run, and some engines self-prime while many do not.

What priming involves

Depending on the engine, it can mean using a hand primer pump, cracking bleed points in a particular order, filling filters before installing them, or a procedure specific to that engine.

Doing it in the wrong order or missing a bleed point leaves air in the system and the engine will not run or will run rough and die. This is where a lot of roadside fuel deliveries turn into a longer job than expected.

The fuel pump takes the damage

The transfer pump is cooled and lubricated by the fuel moving through it. Running dry means it runs without either, and repeated dry runs shorten its life considerably.

A pump failure is a different order of problem than an empty tank, and it happens somewhere less convenient than a fuel stop.

Debris from the bottom of the tank

Sediment and water settle in the bottom of a tank. Running it to empty draws that material into the system, which plugs filters and can reach injection components.

If a truck plugs a filter shortly after running dry, that is the reason, and it may plug more than one before the tank settles.

If you run out and get fuel delivered, expect the possibility of a filter change too. Whatever was in the bottom of that tank is now in the filter.

On the shoulder

Getting fuel to a truck is the easy part. Getting the truck running afterward is the part that takes knowledge of that particular engine.

A driver who knows their engine's priming procedure and has the tools can often do it. A driver who does not is better off having somebody come who does, rather than cranking until the batteries are dead.

Why it happens

• Gauge problems, particularly a sender that reads high
• A leak nobody noticed
• Longer distances between stops than planned
• Idling more than expected in heat, which burns fuel with no miles
• Drawing from a tank that is empty while another one has fuel, on a two-tank setup with a crossover problem

That last one is worth knowing. A plugged crossover line or a valve in the wrong position means you can run out with hundreds of gallons on board.

Cold weather adds a second problem

Gelled fuel produces the same symptoms as an empty tank — the engine starves and quits. If it is cold and the tank is not empty, gelling is the suspect rather than fuel level.

The panhandle does not gel fuel most nights and it does on the cold ones, and trucks running north out of here see worse.

After you are running again

Watch it for the next hundred miles. A truck that ran dry and has been primed can still have air working its way out of the system, and it can still plug a filter with whatever came off the bottom of the tank.

A truck that dies again twenty minutes down the road is not a mystery. It is the rest of the same problem.

Two-tank setups

Trucks with two tanks and a crossover have a specific failure that looks exactly like running out of fuel: the crossover line plugs or a valve is closed, and the engine starves off one tank while the other is full.

The tell is a fuel gauge that does not match what the engine is doing. Worth checking before assuming the tank is genuinely empty.

It is also worth knowing which tank your engine actually draws from, because it is not always obvious and it matters when you are deciding where to put the fuel.

If you are out of fuel, or you have fuel and the engine will not prime, call (850) 495-0366. Dispatch answers 24 hours and we come with fuel and with the tools to bleed the system so the truck actually runs when we leave.