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5

STARTING THE ENGINE

1.  Open the fuel shut-off valve, (if equipped).
2.  Move choke control to Choke or Start position.
3.  Push throttle to Fast position (if equipped). Operate the engine 

with the throttle in Fast position.

4.  Turn key to Start position (hold until engine starts, but not 

more than 5 seconds). To prevent damage to starter, allow 

starter to cool for one minute between attempting to restart.

5.  A) If the engine FAILS TO START, go to Step 6.
 

B) If the engine STARTS, go to Step 7.

6.  Push the choke lever to the HALF CHOKE POSITION. Repeat 

step 4.

• If the engine STILL FAILS TO START, repeat Steps 1-5.

7.  Move the choke lever to the Off POSITION by pushing it in or 

move choke control to Run position.  Allow engine to warm 

up for two minutes.

NOTE:

For cold weather starting: make sure the proper engine oil is 

being used.

STOPPING THE ENGINE

1.  Remove load from engine.
2.  Move throttle to SLOW position.
3.  While still running, allow engine to cool for two minutes.
4.  Turn key to OFF position.
5.  Close fuel shut-off valve (if equipped).

LOW OIL PRESSURE SYSTEM

The engine is equipped with a low oil pressure switch that closes 

if the pressure drops below 8 psi. This switch will function in a 

variety of ways dependant on the application and manufacturer.
• The oil pressure switch could be connected to a light or an 

alarm to notify the operator that the oil pressure is low. The 

engine will not shut down.

WINTER/SUMMER INTAKE AIR 
CONTROL (IF SO EQUIPPED)

Under certain weather conditions (temperatures below 40° F (4° 

C) and a high dew point), the engine may experience icing of the 

carburetor and/or the crankcase breather system. To eliminate this 

problem, this engine may be fitted with a winter/summer valve 

(Figure 4). This directs hot air into the carburetor during cold 

weather operation. Always make sure the winter/summer valve is 

in the correct location relative to the weather conditions.

Figure 4 — Winter/Summer Valve

GENERAL MAINTENANCE 
RECOMMENDATIONS

PERFORMING SCHEDULED MAINTENANCE

It is important to perform service as specified in the Maintenance 

Schedule for proper engine operation, and to ensure that the 

engine complies with the applicable emission standards for the 

duration of its useful life. Service and repairs may be performed 

by any capable person or repair shop. Additionally, emissions criti-

cal maintenance must be performed as scheduled in order for the 

Emissions Warranty to be valid. Emissions critical maintenance 

consists of servicing the air filter and spark plugs in accordance 

with the Maintenance Schedule.

CHECKING THE OIL LEVEL

See the "BEFORE STARTING THE ENGINE" section for information 

on checking the oil level. The oil level should be checked before 

each use, or at least every eight (8) hours of operation. Keep the 

oil level maintained.

CHANGING THE OIL AND OIL FILTER

The engine is equipped with an oil filter. Change the oil and filter 

after the 

first eight (8) hours

 of operation. Change the oil and oil 

filter 

every 100 hours

 thereafter. If using this engine under dirty 

or dusty conditions, or in extremely hot weather, change the oil 

more often.
Use the following instructions to change the oil while the engine 

is still warm:
1.  Clean the area around the oil drain plug, remove the plug and 

drain the oil completely into a suitable container (Figure 5).

2.  When the oil is drained, install and tighten the oil drain plug.

Operation

Summary of Contents for GTH - 990

Page 1: ...Owner s Manual GTH 990 33 HP www generac com SAVE this Manual Provide this manual to any operator of the engine...

Page 2: ...Pressure System 5 Winter Summer Intake Air Control If So Equipped 5 Maintenance 5 General Maintenance Recommendations 5 Perfoming Scheduled Maintenance 5 Checking the Oil Level 5 Changing the Oil and...

Page 3: ...h the OWNER S MANUAL and with the engine The engine can operate safely efficiently and reliably only if it is properly operated and maintained Many accidents are caused by failing to follow simple and...

Page 4: ...e is running Never work on this engine or handle any electrical device while standing in water while barefoot or while hands or feet are wet DANGEROUS ELECTRIC SHOCK will result Allow muffler engine c...

Page 5: ...st eight 8 hours of operation Thereafter change oil and filter every 100 hours of operation Change oil more often if engine is operated in dirty or dusty condi tions or if engine is operated under hea...

Page 6: ...ice Proper maintenance and care of the engine assures a minimum number of problems and keeps operating expenses at a minimum See an authorized dealer distributor for service aids and acces sories BEFO...

Page 7: ...d or the crankcase breather system To eliminate this problem this engine may be fitted with a winter summer valve Figure 4 This directs hot air into the carburetor during cold weather operation Always...

Page 8: ...ake Screen Oil Cooler Fins SERVICING THE AIR CLEANER The equipment s air cleaner system is one of the most important items to maintain The engine will not run properly and may be damaged if it is run...

Page 9: ...st have a spark arrestor The spark arrestor must be maintained in good condition by the owner operator Clean and inspect the spark arrestor screen as follows Inspect the screen and replace if it is to...

Page 10: ...The piston is at TDC when it is at its highest point of travel Loosen the rocker jam nut Figure 11 Use a 10mm allen wrench to turn the pivot ball stud while checking clearance between the rocker arm...

Page 11: ...about five 5 minutes to warm it NOTE Alcohol blended fuel or gasohol attracts moisture which can lead to the separation and formation of acids during storage This acidic gas can damage internal engin...

Page 12: ...ve stuck open or closed 11 Engine has lost compression 1 Clean or replace air cleaner 2 Fill fuel tank 3 Drain fuel tank and carburetor fill with fresh fuel 4 Connect wire to spark plug 5 Replace spar...

Page 13: ...11 Notes...

Page 14: ...r equipment but Generac cannot deny warranty solely due to the lack of receipts You should be aware that Generac may deny any and or all warranty coverage or responsibility if your equipment or a part...

Page 15: ...replacement as required maintenance in the Owner s Manual shall be warranted for the period of time prior to first scheduled replacement point for that part If the part fails prior to the first schedu...

Page 16: ...placement to perform well This warranty will not cover repair when normal use has exhausted the life of a part s or engine Failures caused by any external cause or act of God such as collision theft v...

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