186
FUEL SYSTEM
FUEL COMPONENT TESTS
High pressure
• Suspect restricted filter or fuel return fitting of
vapor sperator, damaged pressure regulator in
vapor separator, or restricted fuel return mani-
fold.
Low pressure
• Check fuel supply to fuel lift pump. Refer to Lift
Pump Vacuum Test on p. 187. Higher vacuum
readings indicate restrictions in the fuel supply.
Repair or replace as needed.
• Restricted fuel filter/water seperator assembly.
• Lift pump not supplying adequate fuel to vapor
separator. Refer to Lift Pump Pressure Test
on p. 187.
• If the above requirements are met and vapor
separator remains full of fuel, suspect damaged
circulation pump. Replace vapor separator
assembly.
No pressure
• Check electrical circuit and ground connections
for circulation pump.
• Voltage present and pump does not run. Repair
connection or replace vapor separator assem-
bly.
•
Pressure Regulator Test
Refer to Vapor Separator on p. 191 to remove
vapor separator.
Make sure filter is not clogged. Clean or replace
as needed.
Apply oil to valve and connect pressure pump and
hose to the fuel return fitting of vapor separator.
Apply pressure to check regulator operation. The
pressure should open check valve at approxi-
mately 15 psi (103 kPa).
1. Filter
2. Fuel return fitting
3. Pressure regulator
000249r
2
13
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