Fuel Pump Inlet/Outlet Check Valve Test
The Fuel Pump Inlet/Outlet Check Valve Test should be performed if the fuel system did operate as
described in the Throttle Valve (Needle Block) and Fuel Pump Test.
Ensure the fuel injector line has been reconnected.
With impact hammer standing upright, ensure the fuel tank plug/vent valves and fuel
return shutoff valve are open. Fully close the fuel pump feed shutoff valve. Also ensure
the hydraulic hose from the remote throttle is connected to the throttle valve (needle
block) whip line on the impact hammer (labeled "THROTTLE CONNECTION").
Close the pressure relief valve on the remote throttle and pump the remote throttle to
550 psi (38 bar). This should cause the throttle valve (needle block) to close fully and
prevent fuel from flowing, via gravity, in the fuel return line from the fuel tank to the fuel
Disconnect the fuel line from the bottom of the fuel filter assembly (outlet) and drain any
remaining fuel. Use a suitable container to catch the fuel.
Only a small amount of fuel should flow out.
Release the remote throttle pressure (0 psi). The needle in the throttle valve (needle
block) should be fully open allowing fuel to flow from the fuel tank, through the throttle
valve (needle block), and to the outlet of the fuel pump.
If the inlet and outlet check valves of the fuel pump are operating correctly, there should
not be any fuel flowing out of the disconnected fuel line.
If the fuel flows out of the disconnected fuel line, the problem is the fuel pump.
If the fuel does not flow out of the disconnected fuel line, the problem is the fuel
Reconnect the fuel line to the bottom of the fuel filter assembly (outlet).
Cylinder Compression Test
The Cylinder Compression Test should be performed if the troubleshooting steps in the Hammer Trip
System, Fuel System, Fuel Pump, Throttle Valve (Needle Block), Remote Throttle, and Fuel Injector
sections of Table K-5 have not determined the problem.
Ensure impact hammer is installed on lead tower and the weight of the impact hammer
is resting fully on a pile (or pile adapter).
The lifting pawl of the hammer trip assembly will not be able to engage
with the lifting collar of piston unless the weight of the impact hammer is
fully resting on a pile or pile adapter.