The gauge needle should initially read 28--41 kPa
(0.28--0.41 bar) (4--6 psi), then return to "0" very
slowly. This indicates that the outlet valve and
diaphragm are in good condition. Supply pump is
operating properly and should be reinstalled on
Fuel Supply Pump--Specification
Pressure ....................................................... 28--41 kPa (0.28--0.41 bar)
If the gauge needle initially reads same value as
above and then returns immediately back to "0", the
pump is defective and must be replaced.
The leakage test should be performed if a supply pump
suspected of leaking fuel externally, or internally into the
1. Install an air line on inlet side of pump (C) and apply
140 kPa (1.4 bar) (20 psi) pressure.
2. Hold finger over outlet side of pump (B) or install a
plug. Submerge pump into a container of clean diesel
If air bubbles occur around banded connection
B--Outlet Side of Pump
holding the two halves of pump together (indicating
C--Inlet Side of Pump
leakage), replace pump.
If the diaphragm is bad, there will be leakage
through vent holes (if equipped) and around the
rocker arm. Replace pump as necessary.