Speedometer not working is due to the vehicle speed sensor. With the 4.6 engine, this is located on the transaxle at the rear of the engine. On the 4.9, it's on the right front of the engine.
You need to get all of the diesel out of the fuel system before flushing. Drop the tank and drain it, disconnect the fuel line before the fuel filter and hot wire the fuel pump. Something like that. THEN you can use the fuel system cleaner to clean out the injectors.
Monday, February 6th, 2012 AT 6:48 PM