Section 13: Troubleshooting - Generac Power Systems GN190H Service And Repair Manual

SECTION 13: TROUBLESHOOTING

PROBLEM SOLVING
INTRODUCTION:
Problems that affect engine operation may be classified as
one of, or a combination of two or more of the following:
• Engine will not start.
• Engine starts with difficulty.
• Engine lacks power.
• Engine vibrates.
• Engine overheats.
• Engine burns oil.
In many cases, the cause of a problem will be readily appar-
ent. If this is not the case, check engine compression, as well
as the ignition and fuel systems. Such a check can be per-
formed quickly and is the best method of finding the cause
of a failure. In addition, such a check may provide early
detection of future failures.
CHECK COMPRESSION:
To check engine compression, remove the spark plug. Insert
an automotive type compression gauge into the spark plug
hole. Crank the engine until there is no further increase in
pressure. The highest reading obtained is the engine com-
pression pressure.
MINIMUM ALLOWABLE COMPRESSION PRESSURE
COLD ENGINE
GN-190, GN-191, GN-220
60 psi
If compression is poor, look for one or more of the follow-
ing causes:
Loose cylinder head bolts.
Failed cylinder head gasket.
Burned valves or valve seats.
Insufficient valve clearance.
Warped cylinder head.
Warped valve stem.
Worn or broken piston ring(s).
Worn or damaged cylinder bore.
Broken connecting rod.
Worn valve seats or valves.
Worn valve guides.
CHECK IGNITION SYSTEM:
See "Testing the Ignition System" in Section 8 (Page 31).
CHECK FUEL SYSTEM:
Make sure the fuel tank has been properly filled with the
correct fuel. If the engine is equipped with a fuel shutoff valve,
make sure the valve is open. Make sure fuel is flowing through
the fuel line and to the carburetor. Adjust the carburetor as
needed. Make sure the choke closes all the way. If engine
still will not start, remove and inspect the spark plug.
If the plug is WET, look for the following:
1. Overchoking.
2. Dirty air cleaner.
3. Excessively rich fuel-air mixture.
4. Water in the fuel.
5. Fuel leaking past the carburetor float needle.
If the plug is DRY, look for the following:
1. Carburetor mounting gasket leaks.
2. Dirt or gum in carburetor or fuel line.
3. Carburetor float needle stuck closed.
4. Inoperative fuel pump (if so equipped).
5. Clogged fuel filter (if so equipped).
One way to determine if fuel is reaching the engine com-
bustion chamber is to remove the spark plug and pour a small
amount of gasoline into the spark plug hole. Reinstall the spark
plug and crank the engine. If engine fires a few times then
quits, check for the same conditions as a dry plug.
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