Fuel Pump Pressure

Purpose:
To determine if there is sufficient fuel pressure for starting.

Recommended Procedure:
Connect Rotunda High Fuel Pressure Adapter 014-00931-3 or equivalent to the Schrader valve mounted in the fuel regulator block. Connect a line for a 160 psi gauge to the adapter. Crank engine at 100 rpm minimum and measure maximum fuel pressure.

Possible Causes:

  • A fuel filter could cause high restriction and low fuel pressure because of dirt or fuel jelling in cold ambient temperatures. Change filter and retest. (Note: It may take a couple of crank cycles to purge the air out of the fuel system.)
  • Debris in the fuel regulator valve will cause low fuel pressure. Disassemble, inspect and clean.
  • A kinked or severely bent fuel supply line or blockage at the pickup tube could cause restriction and therefore low fuel pressure.
  • A loose fuel line on the suction side of the fuel system could cause air to be ingested into the system and cause low fuel pressure.
  • The fuel pump could have internal damage, e.g., ruptured diaphragm, seized plunger or leaking check valves.

Tools Required:
0 to 160 psi fuel pressure gauge.
Rotunda High Fuel Pressure Adapter 014-00931-3 or equivalent line with 1/4-inch NPT fitting.