Generac — Cylinder Balance Test
Testing & diagnosis · Ignition / cylinders
From a Generac service manual covering: 0D3358, 0D7675, 0D9033, 0D9708, 0E0038, 0E3342, EVT-04174-0, EVT-04198-0, EVT-04629-0, EVT-04629-1, EVT-04630-0, EVT-04712-0…. Check it applies to your exact model before use.
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Procedure
- Attach an ignition tester (Generac P/N 0C5969) between the spark plug lead and each spark plug
- Start and run engine at top no load speed and note spark at ignition testers; equal spark means problem is not ignition related
- Note RPM of engine
- Ground out one cylinder by contacting ignition tester and a good ground on engine, and note RPM loss
- Ground out the other spark plug and note the RPM loss
- If the difference between the two cylinders does not exceed 75 RPM, the amount of work the two cylinders are doing should be considered equal
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Two cylinders equal if RPM difference does not exceed 75 RPM
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.