Question on Specific Graviety

[Zap]

Does anyone know what effects specific graviety of diesel fuel has on our trucks? I just got my truck back after approximate two weeks in the shop. They changed the injectors due to rough ideling at start up and large amounts of bluish white smoke. The problem is the truck still smokes when started on a cold morning. The tech said GM told him to check the fuel for specific graviety and if it was under 38 that was the cause of the problem. My fuel tested at 32. So he said it was a fuel problem and could do no more. Problem is my brother's truck uses the same fuel with no problem. Any ideas.

[mackin]

ZAP


=>API Gravity

This is a measure of fuel

[DonG]

Zap,

#2 diesel is produced to a gravity spec. Some use Specific Gravity and other refiners use API Gravity. The 38 you mention is an API Gravity number. #2 diesel has a spec. range of about 30 API to 40 API Gravity. When GM manufactures an engine to use a certain fuel, it must be able to use that fuel if the fuel is within the required specification for that fuel. Unfortunately, each state can set their own limits on fuel specifications. You will need to know if 32 API Gravity is legal for diesel fuel in your state.

In actual practice, 32 gravity is a lot heavier than 38 gravity, and it is more difficult to pump, and atomize. But that should not be a signifcant reason for the truck not to operate properly.

Good Luck, Don