FMC M12-HD, Operation & Maintenance Manual, Page: 17 / 20

17
Trouble-shooting Guide
No flow from pump
Tank is empty
Inlet valve is closed
Inlet strainer is clogged with debris
Crankshaft is not turning
Insufficient pressure from pump ONLY
Pump speed is too slow
Relief valve improperly adjusted and by-passing fluid
Oversize or worn nozzle on equipment
Worn pump valves
Excessive leakage from pump seals
Insufficient flow from pump ONLY
Pump speed is too slow
Relief valve improperly adjusted and by-passing fluid
Worn pump valves
Excessive leakage from pump seals
Insufficient flow OR pressure AND rough operation
Valve Problem:
Pump valve stuck in open or closed position
Valve assembly is damaged or unseated
Valve seat is washed out
All pump cylinders not primed
nlet strainer is clogged with debris
Excessive gas in liquid due to:
Air leaks in suction line or fittings
High spots in suction line that allow formation of gas pockets
Vortex in tank near inlet pipe opening
Pump is cavitating due to:
Insufficient NPSHa (tank head or charge pressure)
Fluid viscosity is too high
Inlet line is too long and/or too small diameter
Pump runs rough, knocks, or vibrates ONLY
Loose piston assembly
Valve assembly is damaged or has unseated
Pump is cavitating due to:
Insufficient NPSHa (tank head or charge pressure)
Fluid viscosity is too high
Inlet line is too long and/or too small diameter
Worn or damaged power frame components
Pump is sucking air across worn piston cups
Suction pressure fluctuates rapidly
Pump is cavitating
Fluid leaking from pump
Piston cups are wearing and about to fail
Fluid cylinder bolts are not properly tightened
Fluid cylinder o-rings (or gaskets) are damaged
Piston assembly o-rings are damaged