Try this info;A 6.6 diesel engine equipped vehicle may be brought in for a hard start/no start only when outside temperatures are below freezing. If the vehicle is moved into a heated shop the vehicle will start normally.
Fuel gelling or waxing (also known as the cloud point) may induce a hard start or rough running condition. Fuel waxing may also restrict the amount of fuel flow through the fuel filter. A high fuel system vacuum reading will be found if the system is checked when the fuel is cold and waxing.
If a below freezing hard start/no start has been verified it may be caused by fuel contamination, poor fuel quality, or fuel waxing. There are three different scenarios that may be found for cold weather hard start/no start fuel concerns.
Recommendation/Instructions:
If a below freezing hard start/no start has been verified it may be caused by fuel contamination, poor fuel quality, or fuel waxing. There are three different scenarios that may be found for cold weather hard start/no start fuel concerns.
Water in the fuel system can freeze and restrict fuel flow right at the fuel tank. Open the fuel filter drain and get a large fuel sample out of the fuel filter. If water is found in the fuel system it may be the cause of the no start or hard start condition. The water in the fuel tank will freeze and restrict the fuel flow through the fuel pickup screen. During the hard start/no start condition monitor the fuel system vacuum readings to diagnose the concern. Normal fuel system readings when cranking are 1 to 2 inches Hg (in/Hg) of vacuum. A frozen restricted fuel system can reach 10 in/Hg of vacuum or higher while cranking.
In extremely cold temperatures fuel suppliers change to a winter blend number 2 diesel fuel. The fuel API on winter blend fuels is approximately 35 to 44 depending on the location. Fuels with an API below 35 to 44 (summer blend fuel) would have a higher possibility of waxing. Monitor the fuel system vacuum readings to diagnose the concern. Normal fuel system readings when cranking are 1 to 2 in/Hg of vacuum. Vacuum readings at 10 in/Hg of vacuum or higher would suggest a waxed fuel system.
Biofuels can have a cloud point (the time at which fuel starts to wax) of 10 to 20 degrees higher than a winter blend number 2 diesel fuel. If the customer is using a biofuel blend of 20 percent or higher, see if they can find a winter blend number 2 diesel(5 percent or less biofuel). Biofuel will also induce a high fuel system vacuum reading if checked when the fuel is waxed. The National Bio Diesel website can be accessed at "www. Biodiesel. Org" and used for customer questions.
Note: Fuel waxing concerns should not be considered a warrantable condition. Fuel quality and waxing properties should be discussed with the customer. Use of engine block heaters in extreme cold temperatures will alleviate some fuel waxing concerns.
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Saturday, January 24th, 2009 AT 1:09 PM
