Mack E7 Service Manual page 277

5-101.bk Page 5 Friday, March 17, 2006 11:05 AM
Possible Cause
1. Air in fuel system.
2. Accelerator linkage loose or out of adjustment.
3. Restricted fuel lines or stuck overflow valve.
4. High idle adjustment set too high.
5. Chassis equipped with MACK Maxi-Miser: Air
leaks in the air supply line or defective control
valve.
6. Fuel injection pump calibration incorrect.
7. Internal fuel pump governor wear.
Possible Cause
1. Loose vibration damper hub nut bolt.
2. Defective or damaged vibration damper.
3. Fan blade not balanced.
4. Engine supports loose, worn or defective.
5. Engine misfiring or running rough.
Possible Cause
1. Insufficient air for combustion.
2. Excessive exhaust back pressure.
3. Improper grade of fuel.
4. Faulty fuel injection nozzle.
5. Improper injection pump-to-engine timing.
200 TROUBLESHOOTING
ENGINE WILL NOT ACHIEVE NO-LOAD GOVERNED RPM
1. Check system for air leaks and correct as required. Air will
generally enter the fuel system on the suction side of the fuel
transfer pump.
2. Check linkage. Make necessary adjustments.
3. Check flow in fuel lines. Check overflow valve for defects, improper
setting, sticking, or defective spring.
4. Check high idle adjustments. Adjust as required.
5. Leaks in the air supply line to the transmission, or from the
transmission to the fuel injection pump governor, will restrict
maximum engine rpm in all gears. Check all lines and connections
for leaks and repair as required. Replace control valve if
necessary.
6. Remove injection pump and nozzle assemblies from the engine.
Send the pump to an authorized MACK Fuel Injection System
Repair facility for repair and recalibration. Then reinstall the pump.
7. Remove the injection pump. Send the pump to an authorized MACK
Fuel Injection System Repair facility for repair and recalibration.
Then reinstall the pump.
EXCESSIVE ENGINE VIBRATION
1. Check condition of mounting. Make necessary repairs and
retorque.
2. Replace damper if it is verified as damaged or defective.
3. Loosen or remove fan belts. Run the engine for a short period of
time at the rpm where the vibration was most noticeable. If the
vibration disappears, replace the fan assembly.
4. Tighten all mounting bolts, or replace components as required.
5. Check items listed in ENGINE MISFIRES in this section.
EXCESSIVE BLACK OR GRAY SMOKE
1. Check air cleaner for restrictions. Check inlet manifold pressure,
and inspect the turbocharger for proper operation. Repair
or replace as required.
2. Check for faulty exhaust piping or restrictions in the muffler. Repair
or replace as required.
3. Drain fuel from tank(s). Replace fuel filters and fill tank(s) with
MACK-specified diesel fuel.
4. Isolate faulty nozzle and replace. Refer to item 7 in ENGINE
MISFIRES in this section.
5. Check timing and adjust as required.
Correction
Correction
Correction
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