Generac Power Systems NP-40G - Manual (Page 113)

Section 7.2- ENGINE DC CONTROL SYSTEM
3. If there is no DC output from the circuit board
to Wire 14, replace the Engine Controller circuit
board.
Test 22-Test Automatic Choke
DtSCUSSION:
Refer to Section 3.5, "AUTOMATIC CHOKE“.
TEST PROCEDURE:
See Section 3.5.
RESULTS:
1. Adjust or repair choke system as necessary.
2. If choke is good, go to Test 23.
Test 23- Check Carburetion
DISCUSSION:
If the engine won’t start or if it starts hard and
runs rough, one possible cause of the problem is
carburetion.
PROCEDURE:
Before making a carburetion check, make sure
the fuel tank has an ample supply of clean fresh
gasoline (gasoline fuel systems) or gaseous fuel.
The Installer may have Installed a gas or gasoline
shutoff valve in the fuel supply system. Make sure
all shutoff valves are open.
Adjust the carburetor as outlined on Page 3.4-2.
Make sure the automatic choke is working properly
and that the choke closes completely.
If the engine will not start, remove the spark plug
and Inspect it. If the plug is WET, look for the
following:
□ Overchoking.
□ Water in fuel.
□ Excessively rich fuel mixture.
□ Intake valve stuck open.
If the spark plug is DRY, look for the following:
□ Carburetor gasket(s) leaking.
□ Fuel line plugged or shutoff valve not opening.
□ Intake valve stuck closed.
□ Inoperative fuel pump.
□ Clogged fuel filter.
RESULTS:
Adjust or repair carburetor or fuel system as
necessary.
Test 24- Check Engine
DISCUSSION:
An engine that will not start or one that starts
hard and runs rough may be caused by a failure In
the engine’s mechanical system.
PROCEDURE:
The first step In checking for an engine problem
Is to perform a compression check. To check en­
gine compression, proceed as follows:
1. Remove the spark plug.
2. Insert an automotive type compression gauge
into the spark plug hole.
3. Crank the engine until there Is no further In­
crease in pressure. The highest reading obtained
Is the engine’s compression pressure.
ENGINE COMPRESSION PRESSURE
NOMINAL PRESSURE:- 60 psi
MINIMUM ALLOWABLE:- 55 psi
NOTE: Full compression pressure cannot be ob­
tained at cranking speeds, due to the action of a
compression release mechanism.
RESULTS:
If compression is poor, look for one or more of
the following possible causes:
1. Loose cylinder head bolts.
2. Failed cylinder head gasket.
3. Burned valves or valve seals.
4. Insufficient valve clearance.
5. Warped cylinder head.
6. Warped valve stem.
7. Worn or broken piston ring(s).
8. Worn or damaged cylinder bore.
9. Broken connecting rod.
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