Generac 3500iO Engine

Tools: socket, feelers/gauges

1. Verify the piston is at top dead center (TDC) of its compression stroke (both valves closed).
2. Remove four (4) screws from rocker cover.
3. Remove rocker cover and rocker cover gasket.
4. Loosen rocker arm jam nut. Turn adjustment screw in to decrease clearance or out to increase clearance.
5. Hold socket steady and tighten lock nut to specification; check clearance and make minor adjustments.
6. After tightening jam nut, recheck valve clearance to make sure it did not change.
7. Install rocker cover, gasket and four screws; tighten to specifications.

Tools: non-metallic feeler gauge

1. Install or replace trigger pickup; ensure routing of wires is correct and not pinched.
2. With rotor in place, set gap to 0.20-0.30mm using the oval holes in the pickup bracket.
3. Align trigger point on rotor outside surface in-line with sensor and check/adjust gap with a non-metallic feeler gauge.
4. Tighten mounting screws to specification and check gap; adjust if necessary.

Tools: compression gauge

1. Remove spark plug.
2. Insert an automotive type compression gauge into spark plug hole.
3. Crank engine until there is no further increase in pressure; record highest reading.

Tools: Small engine tachometer or inductive tachometer

1. With engine running, connect engine tachometer per manufacturer instructions and record the engine RPM.
2. If engine rpm is within rated specs refer to flow chart; if outside range go to Problem 7 flowchart.

⚠ Explosion and Fire. Fuel and vapors are extremely flammable and explosive. Add fuel in a well ventilated area. Keep fire and spark away.

Tools: suitable fuel container

1. Open side panel to expose carburetor (A) and fuel pump (B).
2. Carefully remove fuel line from filter on inlet side of carburetor.
3. Using a suitable container, slowly pull on recoil cord and turn engine over; fuel should flow from fuel line.
4. If fuel does not flow, verify fuel is available to pump; inspect fuel filter and pulse line.
5. If fuel does not flow, replace fuel pump.

Tools: spark tester

1. Disconnect spark plug lead from spark plug.
2. Attach high tension lead to spark tester terminal.
3. Ground spark tester clamp by attaching to cylinder head.
4. Attempt to pull start engine; if spark jumps tester gap, ignition system is working properly.

⚠ Explosion and Fire. Fuel and vapors are extremely flammable and explosive. Add fuel in a well ventilated area. Keep fire and spark away.

Tools: DMM

1. Stop engine and drain fuel from tank.
2. Remove electrical box assembly, back window, and upper enclosure half.
3. Take out C4 connector (do not remove harness of control panel).
4. Set DMM to measure resistance.
5. On female side of C4, connect one lead to Pin 1 and the other to Pin 4; measure and record resistance.
6. If within specified values refer to flow chart; if outside tolerance replace stator.

⚠ Allow engine to cool before draining oil

⚠ Disconnect spark plug wires when working on unit

Tools: funnel

1. Place generator on a level surface
2. Disconnect spark plug wire from spark plug
3. Clean area around oil fill and oil drain plug
4. Remove oil fill cap and wipe dipstick clean
5. Tip unit and drain oil completely into a suitable container
6. Tip unit back to level position
7. Insert funnel into oil fill opening, add recommended engine oil
8. Check oil level with dipstick, adjust to safe operating range
9. Replace oil fill cap and hand-tighten
10. Wipe up spilled oil
11. Dispose of oil properly

⚠ Do not touch hot surfaces

1. Remove clamp to remove retainer
2. Slide spark arrestor screens out from the muffler outlet tube
3. Inspect screens, replace if torn, perforated, or damaged; clean with commercial solvent if not damaged
4. Replace screens and retainer, secure with clamp

1. With enclosure and air duct removed, access fuel filter and fuel pump.
2. Assemble connection lines to proper location.
3. Perform 'Test with Enclosure OFF' to verify operation and no leaks.

1. Place generator on a level surface
2. Clean area around oil fill and oil drain plug
3. Remove oil fill cap and wipe dipstick clean
4. Insert dipstick into oil filler neck without screwing it in
5. Remove dipstick and verify oil level is within safe operating range
6. Add recommended engine oil as necessary
7. Replace oil fill cap and hand-tighten

⚠ Eye protection required to avoid spray from spark plug hole when cranking engine

⚠ Store fuel in a well ventilated area, away from fire and sparks

1. Add fuel stabilizer, run engine 10-15 minutes to circulate stabilizer (fuel can then be stored up to 24 months)
2. If not stabilized, drain fuel into approved container, run engine until it stops from lack of fuel
3. Change engine oil
4. Remove spark plug
5. Pour tablespoon (5-10cc) of clean engine oil or spray fogging agent into cylinder
6. Pull starter recoil several times to distribute oil
7. Install spark plug
8. Pull recoil slowly until resistance is felt, then gently release