The only sure way to get rid of dirty diesel is to remove the tank and flush it out.
Alternatively, it is also possible to hire fuel extractors that fit through the filler neck and pump the fuel out that way into a holding tank for disposal. Most good plant hire firms should be able to help you out with this. However, there is no guarantee that you will be able to pump out every last drop, and you will still have the problem of disposing of the fuel properly.
You don't say how much dirty diesel is involved, but if it were only a few gallons, you could chance it and dilute the dirty diesel by topping the tank full. However, this is a high risk strategy and could lead to simply exacerbating your problems by introducing dirty diesel directly into the engine.
On balance, removing the fuel tank is the best and safest option.
Alternatively, it is also possible to hire fuel extractors that fit through the filler neck and pump the fuel out that way into a holding tank for disposal. Most good plant hire firms should be able to help you out with this. However, there is no guarantee that you will be able to pump out every last drop, and you will still have the problem of disposing of the fuel properly.
You don't say how much dirty diesel is involved, but if it were only a few gallons, you could chance it and dilute the dirty diesel by topping the tank full. However, this is a high risk strategy and could lead to simply exacerbating your problems by introducing dirty diesel directly into the engine.
On balance, removing the fuel tank is the best and safest option.
