SUPPORT AS 4416187 - Caterpillar

Using the 2P-8278 FUEL FLOW TUBE
Normally, No. 2 Diesel Fuel contains about 10% air in solution, although the air is not visible. When the amount of dissolved air exceeds 10%, fuel rate and power output are reduced. This instruction describes the use of the 2P-8278 Fuel Flow Tube to observe the fuel flow and determine engine power loss due to excessive air in the fuel.1. Install the 2P-8278 Fuel Flow Tube 2 in the fuel transfer pump inlet line. Start and warm up the engine. Bleed the fuel system at the filter housing. The bleed valve permits air to purge itself out of the filter housing; however, the observer should remember that the bleed valve can create a venturi effect through the threads in the valve and pass some air out the bleed line. Thus, there appears to be excessive air in the system when air is merely being drawn through the bleed valve.Observe the fuel flow when the engine is idled and accelerated under load. Normally, the fuel is clear as indicated above, and all air is in solution. If the engine has a priming pump and it is suspected to be leaking air into the fuel system, install