What to Do if You Put Gasoline in Your Diesel Vehicle

If you own a diesel vehicle, you have likely been proactive in locating the diesel pumps in your area and looking for the green-colored pump handles when you arrive. However, we all get distracted at times; something can throw us off our game, and in this case, you may have discovered that you accidentally filled your diesel vehicle’s tank with gasoline. If this happens to you, Alderman Automotive offers some advice on what to do.  

We would like to say that it’s no big deal, but that wouldn’t be true. Gasoline and diesel have very different combustion properties. Gasoline is thinner and less oily than diesel; however, most importantly, it has a lower energy density yet is more volatile, igniting at lower temperatures than diesel. An engine designed for one and accidentally fueled by the other faces several unfortunate consequences.  

Engine Symptoms 

You will first notice a significant reduction in engine performance due to incomplete combustion. This can also result in black or blue smoke from excess unburned fuel, causing the engine to run roughly with occasional stalling. You might also hear a knocking sound similar to that of gas engines running on fuel with too low of an octane. Your first start after using the wrong fuel is likely to be normal because the fuel has not yet reached the engine; however, subsequent starts may be difficult and require repeated attempts. If you experience these issues but know you didn’t mis-fuel, it still could be a gasoline issue. Mistakes have been known to happen in the fuel supply chain.  

Potential Damage 

Unfortunately, your issue is not confined to a poorly functioning engine until you properly refill it with diesel. Long-term damage to the engine can manifest in the following ways: 

• Filters and fuel lines: Gasoline will obstruct fuel filters and lines because varnish-like deposits form, hindering the proper flow of fuel. 

• Fuel injectors: The chemical properties of gasoline can harm fuel injectors, clogging the apertures and disrupting their accuracy and capacity to deliver fuel correctly. 

• Pistons and Cylinder Walls: Each combustion will be incomplete, possibly creating hot spots, resulting in overheating and possibly damaging the cylinder walls and pistons. 

• Valves and Valve Seats: Gas contamination can cause valve sticking or damage to valve seats due to carbon buildup, which affects engine compression. 

If You Haven’t Started the Engine 

If you notice the mistake before starting the engine, don’t panic; in fact, congratulate yourself for preventing further trouble. Do not start the engine even just to get away from the pump. Inform the station of your mistake and ask for assistance in pushing your vehicle away from the pump area. If the station has a service facility, you may be in luck if it services diesel engines. Otherwise, you will have to have your vehicle towed to a location where they can:  

• Drain the fuel tank 

• Check to see if the gas has reached anywhere past the tank. 

If You Have Started the Engine 

OK, now things get more involved. Even if you haven’t experienced any of the performance issues discussed above, get off the road and shut off your engine immediately. As above, have your vehicle towed to a facility that services diesel engines. Once there, they will need to: 

• Drain the fuel tank 

• Flush the fuel system including: 

• Fuel pump 

• Fuel filter 

• Injectors 

• Check for any damage to the above and repair and replace accordingly 

None of the subsequent actions are good for your wallet, but acting quickly is always better than delaying or hoping to ride out the issue with a subsequent refueling. If you have further questions, the Service Department at Alderman Automotive is here to help. Although we hope this post brings some clarity to the issue, we hope this never happens in the first place.