FUEL SYSTEM - TM-5-3895-349-14-P0420

FUEL SYSTEM

TESTING AND ADJUSTMENT

FUEL SYSTEM

Either too much fuel or not enough fuel for combustion

6. Check the fuel pressure in the fuel system. Fuel

can be the cause of a problem in the fuel system.

pressure at FULL LOAD must be 30 5 psi (2.1 0.4

kgcm2 ).

Many times work is done on the fuel system when the

To check fuel pressure, remove plug (1) that is just

problem is really with some other part of the engine.

behind the fuel shut-off solenoid on the top cover of the

Finding the source of the problem is difficult, especially

fuel pump housing. Install the necessary fittings and a

when smoke is coming from the exhaust. Smoke coming

gauge to check fuel pressure.

from the exhaust can be caused by a bad fuel injection

nozzle, but it can also be caused by the following:

TESTING 9L6969 FUEL INJECTION NOZZLES

a. Not enough air for good combustion.

Tools Needed: 8S2242 Nozzle Testing Group.

8S2245 Injector Cleaning Tool Group.

b. An overload at high altitude.

987354 Torque Wrench.

98S3093 Adapter.

Burning of too much oil.

8H8505 Combination Wrench.

8H85602 Combination Wrench.

d. Not enough compression.

8S2274 Socket.

8S1589 Socket.

FUEL SYSTEM INSPECTION

9S5031 Socket.

Spanner-type screwdriver.

1. Check the fuel level in the fuel tank. Look at the cap for

5/64" Hex Wrench.

the fuel tank to make sure the vent is not filled with dirt.

An easy check can be made to find the cylinder that is

2. Check the fuel lines for leakage. Be sure the fuel

misfiring, or running rough, and causing black smoke to

supply line does not have a restriction or a bad bend.

come out of the exhaust pipe.

3. Install a new fuel filter. Clean the primary fuel filter if

Run the engine at the speed that gives misfiring.

the machine is so equipped.

Loosen the fuel line nut at a fuel injection pump. This will

stop the flow of fuel to that cylinder. Do this for each

4. Remove any air that may be in the fuel system.

cylinder until a loosened fuel line is found that makes no

difference in engine running. Be sure to tighten each fuel

5. Check the flow of fuel from the constant bleed valve.

line nut after the test before the next fuel line nut is

The flow must be a minimum of 1 pint (0.47 liters) in one

loosened. Check each cylinder by this method. When a

minute at full load speed.

cylinder is found where the loosened fuel line nut does not

make a difference in engine running, test the injection

pump and injection nozzle for that cylinder.

Temperature of an exhaust manifold port, when the

engine is running at low idle speed, can 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, caused by a nozzle with a defect.

CAUTION: Do not test or disassemble nozzles unless you

have the correct service tools.

Before testing a fuel injection nozzle, remove any loose

carbon from the tip of the nozzle with the 8S2258 Brass

LOCATION OF PLUG

Wire Brush. Remove the carbon seal dam. Clean the

1. Plug.

groove for the carbon seal dam and the body of the nozzle

below the groove with