How to Start a Diesel When It’s Out of Fuel
Steps for restarting a diesel when “running on empty” goes too far.
There really isn't "a lot" of detail to give you in this report. For the most part, the long-existing information and procedures on handling a fuel-starved diesel engine are still plenty viable. And thanks to advancements in diesel technology from roughly 2000 to present, many of the physical procedures that were in place for restarting a dry oil-burner—like manually priming the fuel system—are handled by the trucks themselves today.
However, this doesn't mean knowing what to do when your diesel pickup runs out of fuel isn't important. You should always be mindful of how much fuel is in the truck's tank by keeping an eye on the gauge. As long as sending units, pumps and other elements of the fuel system are functioning properly, the fuel-level gauge is the best bet for knowing your approximate mileage range.
So, if (or maybe when) your rig does run out of fuel, what do you do? Well, what you should not do is try and start the engine without fuel, as injectors and other parts could be damaged due to lack of lubrication. Let's start with older setups: trucks like old-body-style Fords with 6.9L IDI diesel engines, first-gen Dodge Rams and such, that require physical input to get their engines re-fired. As you know, diesel engines operate under extremely high fuel pressure. When fuel runs dry, air gets sucked into the system, and it must be vented (bled) out. Adding fuel is the first step, and bleeding the lines and injectors immediately follows. Although the job is somewhat akin to bleeding a brake system and can be messy depending on where in the engine bay the fuel-bleed bolt is positioned, it's typically accomplished with a wrench (sizes vary), a bottle or other receptacle to collect the primed-diesel "blood," and a few rags to clean up the mess with.
Here are the steps:
- For some mechanically fueled engines, loosening fuel-line union nuts (one-by-one) at the injection pump is the best practice. Or, find the location of the bleeder screw (it's actually more of a bolt) that's typically located on the fuel-filter housing. It can also be a Schrader valve in the line, or in the case of 2008 to 2010 6.4L Ford Power Stroke engines, a tool is required for bleeding fuel via the fuel cooler.
- Loosen the bleeder (or union nuts) a few turns. Do not completely remove it/them.
- Using a compressor, pump air into the fuel system via the filler neck, or crank the engine without starting it until fuel and air bubbles flow from the bleeder. Do not crank excessively, as it could overheat the starter or drain the battery.
- Once all the air is out of the fuel system (no more bubbles), tighten the bleeder (union nuts or replace the bolt on a 6.4L's fuel cooler).
- Attempt to start the engine. It should fire up.
Again, newer rigs, let's say from 2000 up, are a lot more self-serving when it comes to the priming process. After adding fresh diesel, bringing it to the front can happen in only a few minutes and without ever leaving the driver's seat. The "how-to" tasks after adding fuel are:
- Prime the fuel system by turning the ignition on (Run position) for 30 seconds, but do not start the engine. This allows the pump to prime the system.
- Turn the ignition off, and then crank it for 15 seconds. If it does not start, repeat the first task and this one until it starts (cycle the key). If the engine does not start after several attempts at priming, take a break and then repeat the process until it does fire up.
- If the engine starts but immediately stalls, wait again for one minute before making another attempt. Once the powerplant does start, allow it to idle for several minutes and check for any leaks before driving.
- In the event the engine just won't start, have the truck towed to a shop or dealership service department for proper diagnosis and repair.
Diesel Technician Society