Generac Power Systems 75, 55, 65 manual TEST 36 - CHECK CARBURETION, TEST 37 - CHECK CHOKE SOLENOID

Section 7

DIAGNOSTIC TESTS

Figure 7-42 – Tightening the Jam Nut

INSTALL ROCKER ARM COVER

1.Use a new rocker arm cover gasket. Install the rocker arm cover and retain with four screws.

RESULTS:

Adjust valves to specification and retest. If problem continues, go to Test 38.

TEST 36 - CHECK CARBURETION

DISCUSSION:

If the engine cranks but will not start, one possible cause of the problem might be the carburetion system.

PROCEDURE:

Before making a carburetion check, be sure the fuel sup- ply tank has an ample supply of fresh, clean gasoline. Check that all shutoff valves are open and fuel flows freely through the fuel line.

Make sure the automatic choke operates properly.

If the engine will not start, remove and inspect the spark plug. If the spark plug is wet, look for the following:

❏Overchoking.

❏Excessively rich fuel mixture.

❏Water in fuel.

❏Intake valve stuck open.

❏Needle/float stuck open.

If the spark plug is dry look for the following:

❏Leaking carburetor mounting gaskets.

❏Intake valve stuck closed.

❏Inoperative fuel pump.

❏Plugged fuel filter(s).

❏Varnished carburetor

If the engine starts hard or will not start, look for the following:

❏Physical damage to the AC generator. Check the Rotor for contact with the Stator.

❏Starting under load. Make sure all loads are discon- nected or turned off before attempting to crank and start the engine.

❏Check that the automatic choke is working properly.

RESULTS:

If problem has not been solved, go to Test 37. If car- buretor is varnished, clean or replace.

1.Remove fuel line at carburetor and ensure that there is an ade- quate amount of fuel entering the carburetor.

2.Remove the float bowl and check to see if there is any foreign matter in bottom of carburetor bowl.

3.The float is plastic and can be removed for access to the nee- dle so it can be cleaned.

4.With all of this removed carburetor cleaner can be used to clean the rest of the carburetor before reassembly.

5.After cleaning carburetor with an approved carburetor cleaner, blow dry with compressed air and reassemble.

Shelf life on gasoline is 30 days. Proper procedures need to be taken for carburetors so that the fuel doesn’t varnish over time. A fuel stabilizer must be used at all times in order to ensure that the fuel is fresh at all times.

TEST 37 - CHECK CHOKE SOLENOID

DISCUSSION:

The automatic choke is active only during cranking. When the Start-Stop Switch is held at “START”, a crank relay on the Engine Controller circuit board is energized closed to (a) crank the engine and (b) deliver a cyclic voltage to the Choke Solenoid via Wire 90. The Choke Solenoid will be pulled in for about two seconds, then deactivate for about two seconds. This cyclic choking action will continue as long as the engine is being cranked.

PROCEDURE:

1.Operational Check: Crank the engine. While cranking, the choke solenoid should pull in about every 2 seconds (2 sec- onds ON, 2 seconds OFF). If the choke solenoid does not pull in, try adjusting the choke as follows.

2.Pre-Choke Adjustment: With the CHOKE SOLENOID not actu- ated, the carburetor CHOKE PLATE should be approximately 1/8 Inch from its full open position. Verify choke is completely open once engine is warmed up. If not, power will be down and emissions will be up. Adjust position of BI-METAL HEATER ASSEMBLY by loosening screws until unit starts when cold and the choke closes when engine is up to temperature. Tighten the screws to complete the adjustment.

3.Choke Solenoid Adjustment: Loosen the screws that retain the CHOKE SOLENOID to its bracket. Slide the CHOKE SOLE- NOID in the slotted holes of the bracket to adjust axial move-

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