Fuel Injectors & Pumps – Section 6.11 Black or Gray Smoke Problem

Section 6.11
Black or Gray Smoke Problem

To determine if an improper grade of fuel oil is causing excessive black or gray smoke, perform the following steps:‪

1. Acquire a fuel oil sample from the vehicle fuel tank(s).
2. Submit fuel oil sample for testing.
3. If evidence of improper grade fuel in system, follow these steps to resolve concern:
   1. Drain the fuel oil tanks; refer to OEM guidelines, and dispose of properly.
   2. Refill the fuel oil tanks with new fuel oil having a cetane number greater than 45.
   3. Test operation.

A faulty fuel injector, such as a blown or plugged nozzle, can cause black smoke. Follow procedures in testing section and in Series 60 service manual (6SE483) or Series 50 service manual (6SE50) to check.‪