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I own a 1999 Toyota Hilux Surf 2.4 Diesel.

Unfortunately a friend filled it with petrol a few months back.

It was drained but had run several miles on the mixture of mainly petrol with some diesel.

It has recently not liked starting in the mornings and seems to miss a cylinder when cold starting and blows grey smoke.

Can you recommend a resolution to this problem please.


From the "Ask Jack" archives - 23 April 2009


I don't want to be the bearer of bad news but this could be a major problem.

Diesels do not like straight petrol for several reasons.

The main reason is oil in the diesel acts as a lubricant for the injector pump, so running petrol through the pump basically means the pump can destroy itself through lack of lubrication.

This is where the problems can escalate. Damage to the pump can mean metal filings are dragged through to the injectors causing them to leak or foul up which may be the reason for the miss-firing / excessive smoke / hard starting.

I'm not sure if your model Toyota has a common rail injection system, but if it has the damage can be more invasive as the system is looped back to the fuel tank.

Any filings etc can in theory be circulated through the whole fuel system and be a major job to repair.

Don't want to over dramatise the situation but you need to get the vehicle looked at ASAP.

Hopefully there is no damage to the pistons due to the petrol having a much lower tolerance to the high compression ratio in a diesel engine.

Don't delay, get it sorted before it does further damage.


Check your glow plugs. If one or more isn't working that cylinder will not be able to ignite the diesel until the engine has warmed up a bit and it will miss and blow grey smoke (unburned diesel). This may or may not be related to the petrol issue - could just be coincidence. If they haven't been changed you've got 12 year old glow plugs and they don't last forever. Also, in my experience, when one goes another will surely follow, change them all as they don't cost much. They are a pain to test - you have to take them out - so when my diesels have done this (Holden HQ wagon w/Nissan LD28 engine, Toyota Surf 2.8, Peugeot 306, Massey Furgeson tractor) I just change all the glow plugs and the problem goes away.