36. Compressor head gasket
Restricted discharge line.
A. Clear restriction or replace line.
Loose head bolts.
B. Tighten evenly to a torque of 25-30 foot
Faulty compressor or head
C. Check for rough or poorly machined
head or block surfaces. Replace necessary
Either too much fuel or not enough fuel for
combustion can be the cause of a problem in the fuel
Many times work is done on the fuel system when
the problem is really with some other part of the engine.
The source of the problem is difficult to find, especially
when smoke comes from the exhaust. Smoke that
comes from the exhaust can be caused by a bad fuel
injection valve, but it can also be caused by one or more
of the reasons that follow:
Not enough air for good combustion.
An overload at high altitude.
Oil. leakage into combustion chamber.
Not enough compression.
FUEL SYSTEM INSPECTION
A problem with the components that send fuel to the
engine can cause low fuel pressure. This can decrease
Check the fuel level in the fuel tank. Look at the
cap for the fuel tank to make sure the vent is not
filled with dirt.
Check the fuel lines for fuel leakage. Be sure
the fuel supply line does not have a restriction
or a bad bend.
Install a new fuel filter. Clean the fuel screen
located in the inlet valve of the fuel transfer
Remove any air that may be in the fuel system.
If there is air in the fuel system, use the priming
pump and loosen the nuts holding the fuel lines
to the outside of the cylinder head, one at a
time. Do this until fuel, without air, comes from
the fuel line connection.
CHECK ENGINE CYLINDERS SEPARATELY
An easy check can be made to find the cylinder that
runs rough (misfires) and causes black smoke to come
out of the exhaust pipe.
Run the engine at the speed that is the roughest.
Loosen the fuel line nut at a fuel injection pump. This
will stop the flow of fuel to that cylinder. Do this for
each cylinder until a loosened fuel line is found that
makes no difference in engine performance. Be sure to
tighten each fuel line nut after the test before the next
fuel line nut is loosened. Check each cylinder by this
method. When a cylinder is found where the loosened
fuel line nut does not make a difference in engine
performance, test the injection pump and fuel injection
nozzle for that cylinder.
Temperature of an exhaust manifold port, when the
engine runs at low idle speed, can also be an indication
of the condition of a fuel injection nozzle. Low
temperature at an exhaust manifold port is an indication
of no fuel to the cylinder. This can possibly be an
indication of a nozzle with a defect. Extra high
temperature at an exhaust manifold port can be an
indication of too much fuel to the cylinder, also caused
by a nozzle with a defect.
The most common defects found with the fuel
injection valves are:
Carbon on tip of the nozzle or in the nozzle
Do not test or disassemble nozzles unless
you have the correct service tools.
NOTE: Do not disassemble fuel nozzles before they
have been tested. See TESTING PENCIL TYPE FUEL