TRUCK SERVICE MANUAL
FUEL SYSTEM
PT (type D) Injector Trouble Shooting The following list
(c) Close the hydraulic valve while the load cell is
of problems is of importance when trouble shooting PT
clamped in position and turn the timing wheel
(type D) injectors:
slowly by hand.
(d) If the load cell indicates more than 50 lbs. [22.7
kg] increase above the clamping load, the cam
Check 1 - Unable To Get Correct Plunger To Cup
and/or shaft and/or cam follower must be
Alignment
replaced.
Cause
Correction
Test cup spray pattern on ST-668. Clean, inspect and
Defective or dirty cup.
repair. Assemble with correct tools and procedure.
Clean and inspect.
Improper assembly techniques.
Clean, inspect and repair.
Defective plunger.
If damaged areas cannot be cleaned up, replace part.
Defective barrel face surfaces.
Check cup to plunger alignment.
Damaged retainer cup seating shoulder or threads.
Improper interpretation of cup alignment.
Correction
Install new gasket each time barrel is removed from
Check 2 - Defective Barrel To Adapter Seal
adapter on 5/16 inch [7.94 mm] type injectors. All 3/8
inch [9.52 mm] type injectors built after January, 1969 do
Cause
not require gasket. Lap surface.
Inspect and replace if interference occurs.
Gasket, when required, torn or creased at time of
assembly.
Correction
Inspect and replace with barrel plunger assembly.
Adapter or barrel face damaged.
Stake plugs with punch.
Roll pins or spiral pins damaged, preventing barrel and
Lap surface.
gasket from seating properly.
Correction
Check 3 - Fuel Leaking Around Retainer
Assemble correctly.
Cause
Barrel cracked.
Leaking barrel plugs.
Defective barrel to cup seal.
Check 4 - Plunger Sticks Or Scuffed
Cause
Cup to plunger misalignment.
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