Blowin' Smoke

An Editorial by dieselmann
Volume 16; December 03: Fuel Contamination

Probably the most costly repair to the PowerStroke is due to fuel contamination. At an average price of $300.00 each for the injectors, good clean fuel is imperative. Contamination either decreases the lubricity of the fuel (water, gasoline, alcohol), or restricts fuel delivery to the injectors. Since the injectors are lubricated, in part, by the fuel either one of these scenarios will result in damage.

Damaged injectors can fail to open fully or at all, which will cause low power, rough running and misfires. If multiple injectors stick you can have a hard or no start, or start/stall concern. In some cases the injector can stick open and this will result in damaged pistons from over fueling or a hydraulically-locked piston. If an engine hydro-locks the piston can crack, the connecting rod or valve push rod can bend or the valve rocker arm can break.

Gasoline contamination presents another problem. Gas is more volatile and burns more quickly than diesel fuel. This gives you short violent combustion before the piston has come up to top dead center. The engine will knock badly from this early combustion. This will cause the piston to crack or melt. A shorter burn time reduces a diesel engine's power because the burning air/fuel mixture will not be pushing the piston down through the power cycle. Normally diesel fuel continues to burn after the piston starts down from top dead center. This long burn time is what give a diesel engine it's power.

The best solution, of course, is prevention. It's best to fuel from a reputable station that has a high volume of diesel sales. This ensures the fuel is not sitting long enough to allow accumulation of moisture and formation of biomass. I wet weather, high humidity regions, or areas where ground water intrusion (flood plain) is a problem you will want to use a fuel conditioner that prevents water accumulation and keeps the fuel de-emulsified (milky fuel/water mix). A fuel conditioner should also improve lubricity to help counter the affects of contamination and prolong injector life. And don't forget to drain your water separator. Even if you are not in wet conditions, you may be able to catch contamination (by inspecting the fuel drained) before it becomes a problem.

If you have your own fuel storage that is not used up fast enough, you will want to treat it with a biocide and either install an automatic circulation system that will periodically pump the fuel through a filter/water separator, or circulate it manually by running the transfer pump and pumping the fuel back into the tank. Your own fuel pump should have its own filter/water separator, too. Storage tanks and in-bed tanks should have a sealed filler cap to keep water and dirt (and dog hair!) out of the fuel.

If you do end up getting contaminated fuel, you need to remove it as soon as possible. If you put gasoline into the fuel tank by mistake, do not start the engine. If you do not realize your mistake right away, shut down the engine as soon as you do. The fuel tank will need to be drained and the fuel system purged. In the case of material contamination (dirt, biomass, ect) the tank may need to be flushed. Drain and replace the fuel filter. On the PowerStroke there are fuel passage drains on the rear of the heads that should be loosened to remove the contaminated fuel from the heads. Add a fuel lubricity conditioner to the fuel tank when refilling. If possible do not use a conditioner that contains cetane boost--you don't what the fuel to be any more volatile. If you cannot find a suitable lubricity modifier, ATF can be used (approximately one quart to every ten gallons of fuel). I recommend pumping fuel throughout the system before closing the filter drain and tightening the head drain plugs. Take it easy on the vehicle until you are sure there are no lingering affects of the contaminated fuel. Continue to use the lubricity modifier for the next couple of tank fulls.

Finally, keep in mind that both gasoline and diesel is considered hazardous materials in many areas and must be disposed of properly.

Charles David Ledger; dieselmann2003

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