“I filled my common rail diesel with petrol! What can I do now?”

Don’t laugh — a diesel filled with petrol is more common than you think, especially if you’re refuelling at an unfamiliar outlet and you’re in a hurry. (Admittedly, I’ve done it myself!) Common rail diesel engines (CRDs) have incredibly fine tolerances, operate at extremely high pressure, and are intolerant of contamination. Run petrol in a CRD and you can expect damage bills of around $10,000.

Short answer: if you’ve put petrol in your common rail diesel, don’t panic — and don’t assume the pump and injectors are destroyed. For minor contamination, a heavy dose of CRD Fuel Enhancer can clean and re-lubricate the system without needing to drain the tank. For heavier contamination, drain and purge first, then dose with CRD. In many cases the components are fine, and a costly replacement isn’t needed.

Two weeks ago, a Toyota dealership that uses our Cost Effective Maintenance products extensively rang to tell me about a near-new Prado diesel that had been tilt-trayed into their workshop. The owners were on holiday and had driven 240km after unwittingly filling up with 130L of petrol. The vehicle stopped and couldn’t be restarted. The service manager advised them that driving with that much petrol for such a distance would almost certainly mean a destroyed fuel pump and injectors, with possible further internal damage.

Saving a Common Rail Diesel Filled With Petrol

The tank needed to be drained, and fresh diesel used to purge out all traces of the contaminated fuel. At this stage, out of curiosity, the technician decided to use 20L of diesel strongly dosed with CRD Fuel Enhancer to clean and lubricate the system.

On cranking the engine, he was amazed that it actually started. It ran very rough, of course — but after about 10 seconds, and totally unexpectedly, it settled into a normal idle. It road-tested fine, and follow-up contact with the owner has since confirmed no detectable damage.

Three Conclusions

1. Many (or most) of the pumps and injectors replaced after petrol-fuelling incidents are not actually damaged at all.
2. Many (or most) customers are paying out $10,000 repair bills unnecessarily for petrol contamination.
3. CRD Fuel Enhancer restores proper working operation to affected fuel pumps and injectors.

Important: this is one remarkable result, not a guarantee — outcomes depend on how much petrol, how far it was driven, and the engine. For minor contamination, a heavy dose of CRD Fuel Enhancer can be enough on its own without draining the tank; for heavier contamination, drain and purge first, then dose with CRD. Either way, it’s well worth trying before you authorise thousands in replacement parts.

Not sure how badly the fuel is contaminated? An SOS18 Diesel Fuel Sample Kit lets you send a fuel sample off for laboratory analysis, so you know exactly what you’re dealing with before deciding whether a simple heavy dose of CRD will do, or whether the tank needs draining first.

For related reading, see why you usually don’t need to replace your common rail injectors, our overview of common rail diesel problems, and how CRD Fuel Enhancer works.

For more information on how to save a diesel engine filled with petrol, give the team at Cost Effective Maintenance a call on 07 3376 6188.

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