Why generators show "voltage drops under heavy load": 19 documented causes and brand-specific fixes, compiled across 8 manufacturers.
Engine lacks power. Poor compression. Faulty carburetion. Dirty carburetor air cleaner. Choke. Carbon in cylinders or in carburetor venturi. Restricted exhaust line.
2 brands- Cummins/Onan: Tighten cylinder heads and spark plugs. If still not corrected grind the valves. Replace pistons if necessary. Check the fuel system. Clean, adjust or repair as needed. Clean. Refill with proper oil. Choke plate must be wide open at operating temperature. ' Remove carbon. Clean or increase the size.
- D.W.Onan: Tighten cylinder heads and spark plugs. If still not corrected grind the valves. Replace pistons if necessary. Check the fuel system. Clean, adjust or repair as needed. Clean. Refill with proper oil. Choke plate must be wide open at operating temperature. ' Remove carbon. Clean or increase the size.
Engine lacks power, Poor compression.
2 brands- Cummins/Onan: See remedies under 'Engine Misfires at Heavy Load'. Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace piston rings if necessary.; Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace piston rings if necessary.
- Onan Electric: Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace piston rings if necessary.
Engine lacks power. Poor compression. Faulty carburetion. Dirty carburetor air cleaner. Choke partly closed. Carbon in cylinders or in carburetor venturi. Restricted exhaust line. improper governor adjustment.
2 brands- Cummins/Onan: See remedies under ‘'Ea- gine Misfires at Heavy Load”.
- Prestolite: See remedies under ‘'Ea- gine Misfires at Heavy Load”.
Engine lacks power. Poor compression.
2 brands- Garretson: Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace pistons if necessary.
- NEC: Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace pistons if necessary.
Engine lacks power. Poor compression. Faulty carburetion. Carburetor air cleaner. Choke. Carbon in cylinder. Restricted exhaust line.
1 brand- Cummins/Onan: See remedies for engine missing under heavy load. Tighten cylinder head and spark plug. If still not corrected, grind the valves. Replace piston rings, if necessary. Clean, adjust or replace parts necessary. Clean. See that it opens wide enough. Remove carbon. Clean or increase the size.
Engine lacks power. Poor compression. Faulty carburetion. Restricted air cleaner. Excessive choking. Carbon in cylinders. Restricted exhaust line.
1 brand- Cummins/Onan: See remedies for engine missing under heavy load. Tighten cylinder head and spark plugs. If still not corrected, grind the valves. Replace piston rings, if necessary. Check the fuel system. Clean, adjust or replace parts necessary. Clean and refill. See that choke opens properly. Remove carbon. Clean or increase the size.
Engine lacks power. Poor compression. Faulty carburetion. Dirty air cleaner. Restricted exhaust line. Choke partially closed.
1 brand- Cummins/Onan: See remedies for engine misfires under heavy toad Tighten cylinder head & spark plugs Clean the tuch syatern Clean, adjust or replace parts necessary Clean, Clean or increase the size See that itepen. tully
Poor compression. Faulty injection. Dirty air cleaner. Restricted exbaust line.
1 brand- Cummins/Onan: Tighten cylinder head and spark plug. If still not corrected, grind the valves. Replace piston rings, if necessary. Check the fuel system. Clean, adjust or replace parts necessary. Clean.
Engine lacks power, Poor compression, Faulty injection, Dirty air cleaner, Restricted exhaust line
1 brand- Cummins/Onan: See remedies for engine misfires, Tighten cylinder head and glow plug. If still not corrected, grind the valves. Replace piston rings, if necessary., Check the fuel system. Clean, adjust or replace parts necessary, Clean
Faulty carburetion
1 brand- generatorpartspro: Carburetor air cleaner: Check the fuel system, clean adjust or replace parts necessary Choke partially closed: See that it opens wide Carbon in cylinders: Remove carbon Restricted exhaust line: Clean
Engine lacks power. Poor compression. Faulty carburetion. Dirty carburetor air cleaner. Choke partially closed. Carbon in cylinders or in carburetor venturi. Restricted exhaust line. Improper governor adjustment.
1 brand- Cummins/Onan: Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace piston rings if necessary. Check the fuel system. Clean, adjust or repair as needed. Choke plate must be wide open at operating temperature. Remove carbon. Clean or increase the size. Refer to ADJUSTMENTS.
Engine lacks power, Poor compression, Faulty carburetion, Dirty air cleaner, Choke partially closed
1 brand- Cummins/Onan: See remedies for engine misfires under heavy load, Tighten cylinder head and spark plug. If still not corrected, grind the valves, Replace piston rings if necessary, Check fuel system, Clean, adjust or replace parts necessary, Clean air cleaner, See that choke opens wide
Engine lacks power. Poor compression. Faulty carburetion.
1 brand- Cummins/Onan: See remedies for engine misfires under heavy load. Tighten cylinder head & spark plugs. Clean the fuel system.
Engine lacks power. See remedies for engine mising under heavy load. Poor compression. Tighten cylinder head and spark Plugs. If still not corrected, grind the valves. Replace piston rings, if necessary.
1 brand- Cummins/Onan: See MAINTENANCE AND REPAIR.
Engine lacks power, Poor compression, Faulty carburetion, Dirty carburetor air cleaner, Choke, Carbon in cylinders or in carburetor venturi, Restricted exhaust line.
1 brand- Cummins/Onan: See remedies under 'ENGINE MISFIRES AT HEAVY LOAD'. Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace piston rings if necessary. Clean, adjust, or repair as needed. Clean. Refill with proper oil. Choke plate must be wide open at operating temperature. Clean. Remove carbon. Clean or increase the size.