Craftsman 143.991200 Specifications download pdf (Page 43)

TESTING PROCEDURE

STARTING CIRCUIT

1. Check the power source using an electrical tester and following the tester's recommended procedure.

Make sure the battery meets the minimum battery voltage requirements found in the original equipment

manufacturer's service manual.

2. Check the electric starter terminal for the required voltage (12v D.C. or 120v A.C.) using a voltmeter.

CAUTION: FOLLOW ALL SAFETY PRECAUTIONS WHEN TESTING FOR A.C. VOLTAGE, ELECTRIC

SHOCK CAN KILL.

3. Check wiring, connections, fuses, ignition or starter switch, safety switches, or solenoid for continuity

using a ohmmeter or a continuity light. Repair or replace as necessary.

4. Remove all equipment loads from the engine. Take off all drive belts, chains, and couplers to isolate

the engine from the equipment it is powering.

5. Try to turn the engine over using the recoil assembly if equipped. If the engine doesnt turn over, a

mechanical binding may be the cause. Check for proper lubrication (oil level and viscosity) and check

for electric starter gear and flywheel ring gear interference. If no problem is discovered, the problem is

an internal failure.

6. If the engine binds only on the compression stroke, check the engine valve clearance per the

specification table in Chapter 10. If the valve clearance is within the specifications, the camshaft

(compression release failure) may require replacement. Valve clearance not within the listed

specifications will require resetting the rocker arms to obtain the proper clearance.

7. If the engine turns over freely, the electric starter should be replaced or disassembled and checked.

See "Service" in this chapter. 120 volt starters labeled UL Listed/CSA Approved can be serviced;

however, starters labeled CSA must only be replaced. If the preceding steps fail to correct the problem,

the engine will require to be disassembled to find the mechanical failure. See Chapter 9 under

"Disassembly Procedure".

CHARGING CIRCUIT

The following pages will show wiring diagrams of several Tecumseh charging systems. The charging system

used on the engine is best identified by obtaining the engine model number and the specification number on

the engine. Consult a Tecumseh dealer or a parts manual to identify the charging system. To make many of the

tests it is necessary to run the engine and measure alternator output with a voltmeter. When making voltage

tests with the engine running, it is not necessary to take readings at all the listed R.P.M.s. Checking at one of

the speeds is sufficient.

BATTERY GROUND (BL)

ELECTRIC STARTER

LEAD (ORG)

BLACK

RED

(-) ENGINE GROUND

(+) POSITIVE LEAD

MAGNETO GROUND

(GR)

D.C. OUTPUT

LEAD (RED)

In some cases an open circuit D.C. check cannot be

made. A SCR (Silicon Controlled Rectifier) is located

in the circuit which requires a minimum turn on

voltage to allow it to conduct. Without the battery in

the circuit this turn on voltage is not present. The

SCR senses this and there will be no D.C. output

from the regulator / rectifier.

Each charging system has its own testing procedure.

Test the charging system using the applicable

procedure found on the following pages.

350 Milliamp Charging System

CHECKING THE SYSTEM: The battery must be in

the circuit to perform the test properly. Set the

voltmeter to the 0 - 20 D.C. volt scale. Connect a

voltmeter across the battery. The voltmeter should

read the battery voltage. Start the engine. With the

engine running, there should be an increase in the

voltage reading. If there is no change in the voltage

reading, the alternator is defective and should be

replaced. See Chapter 9 for "Disassembly Procedure"

(diag. 7).

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Craftsman 143.991200 Specifications Page 43

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