U-JOINT 9N8660 - Caterpillar

Symptom Based Troubleshooting
Use the following possible cause scenarios and corrective actions to evaluate the root issue that is being experienced on the fast fill fuel system.Possible Cause Scenarios
Immediate Shutoff (No Fill)
Under Fill of Fuel Tank
Intermittent Shutoff During Refueling
Overfill of Fuel Tank.
Fuel Leaks at Nozzle During Fill-up
Table 1
Symptom Possible Cause Possible Component Corrective Action
Immediate Shutoff (No Fill) Fuel inlet valve will not open Check if fuel inlet valve orifice to signal line is obstructed
Check if fuel inlet valve is stuck
Check if orifice on inlet valve is plugged
Check if vent is blocked or clogged
Signal line indicates full Check if float is stuck in the open position
Check signal line for kink or obstruction
Underfill Nozzle shut off pressure set too low Weak nozzle seals Rebuild nozzle
Each component has a normal pressure restriction. Look for severe restrictions which may cause problems.
System pressure exceeds shut off set point pressure (check each item) Receiver Check for proper receiver
Vent Outlet restricted Check vent outlet and ensure that the vent operates freely
Check if the overflow tube is not kinked or bent
Signal line restriction Clean signal line with compressed air if needed
Check for kinks in signal line
Check for debris on shut off valve strainer orifice
Check for debris inside the shut off valve
Optional filter element restriction causing back pressure Check and clean or remove the filter
Shut off valve restricted or shut Check valve for proper operation
Actuate valve plunger to verify the valve moves freely.
Float lifts too soon Vehicle is being filled on side slope Fill on a level surface
Float sits too low in the fuel tank Check for float stuck in up position.
Sporadic filling Sticky Valve Check shut off valve for sticky operation
Plugged vent Check vent for debris
Check optional vent hose for restriction or obstruction.
Overfill Nozzle not shutting off properly Nozzle spring set too high Check or rebuild nozzle
Signal line not pressurizing Leak in signal line Check signal line for leaks
Check for leaks at back of valve housing
Check for leaks at base of float housing
Check for leaks at O-Rings on signal lines
Float not lifting Check for cracks in the float housing
Check for float operation by tilting back and forth
Check if the machine is on a side slope
Check if the float is installed at an angle
Check if the float is stuck in the down position
Valve not closing Check for stuck valve
Check for broken or torn diaphragm within the shutoff valve assembly
Check signal line operation
Fuel leaks at nozzle during filling Nozzle worn or damaged Nozzle Clean and rebuild nozzle or replace nozzle
Receiver worn or damaged Receiver assembly Replace receiver assembly Component Testing
The following component tests may be used as part of troubleshooting:
Inlet valve operational test
Float Operation (LVCA)
Shuttle Valve Operation (Dual fill)Inlet Valve Operational Test
Remove the float (LVCA) assembly from the top of the fuel tank and disconnect the signal line from the float (LVCA) assembly.
Carefully have another person commence fuel filling of the tank and verify that fuel flow is present from the signal line.
During fuel filling, block the fuel flow at the disconnected end of the