The below video explains what to do if you have put petrol in a diesel car and not started your engine.
With ANY misfuelling, DO NOT start the car as this will start to circulate the contaminated fuel.
The Daily Telegraph has some interesting facts and figures regarding this common mistake.
If you are lucky enough to realise before you start your engine, your contaminated fuel is only contained in your fuel tank.
What damage can it cause?
With modern diesel fuel pumps running at such high pressures, petrol in a diesel car can effect and reduce the lubrication in the pump, causing damage to the pump when the metal components rub together. The petrol can also cause damage to the diesel pump & fuel system seals. How much damage depends on how long the engine was run for after the misfuelling.
This rubbing together in the pump can cause metal particles to be deposited into the fuel and these may be carried along up to the rest of the fuel system. The further the petrol moves along your fuel system, the more expensive the repair. So, if you have already started driving, as soon as you realise you have contaminated your diesel with petrol STOP DRIVING and SWITCH OFF!
Types of Diesel Engine
There are two types of Diesel engine; Gasoline Direct Injection (GDI) & Common rail (HDi), either engine can suffer damage from diesel contaminated with petrol. HDi engines can have damage caused to their injectors, low and high pressure pumps, filters and fuel rail system, the worst case is that you would have to replace some if not all of these parts after a misfuelling situation.
Signs of petrol in a diesel car
Signs of damage
Engine won’t stop once it’s started
This can be caused by damage the petrol has done to the seals on the plunger, which helps deliver the correct amount of fuel. If the seal fails the fuel will keep flowing to the engine.
Losing power at high speed
If you have damaged the fuel pump, you may experience a loss of power at high speed or a sudden loss of power after driving for 20 – 30 minutes.
Put in five litres of petrol or less.
We recommend a full drain on any amount of contamination. If you have put in 5 litres or less of petrol (less than 10% of your tanks capacity) and top up with diesel to a full tank, your vehicle should be able to burn off any contamination.
Put in more than five litres of petrol (10%+)
DO NOT START YOUR ENGINE or put your key in the ignition as this can prime the electric pump in the tank and circulate the contaminated diesel. It is essential to carry out a full drain. Once the contaminated fuel has been removed and the tank filled with the correct diesel there should be no damage to the engine.
Started the vehicle
With this situation, it is recommended to take every precaution to remove all of the contaminated diesel. A full tank drain, and complete fuel system flush is essential to stop or minimise any potential damage from to your vehicle’s fuel system. Once the system has been completely flushed through with the correct fuel and the tank has been filled with diesel, we recommend using a good quality fuel additive to remove any trace of the contaminated fuel.
If you have put petrol in a diesel car and started your engine, the below video covers what to do next.
Driven my car before realising
If you have driven your vehicle before realising your misfuelling mistake, carry out all the precautions as per the instructions in chapter ‘Started the vehicle’, and perform a thorough cleanse of all affected equipment. We would also recommend you change your fuel filter ASAP after the incident, this is a relatively low cost component and is quite simple to install.
NOTE: Some vehicles may suffer emission problems after putting petrol in a diesel car due to contamination of the sensors and controls.
For more information on how a diesel engine works, check out this page