HOW TO DIAGNOSE A CARBURETTOR PROBLEM AT HOME

The Three Classic Carburettor Symptoms

Most carburettor problems show up as one of three things: hard or no starting, rough idle, or dying under load. Each has different causes, but the carburettor is involved in all three.

• Hard or no starting: Fuel isn't getting to the engine, or the mixture is wrong
• Rough idle or hunting: Idle circuit is blocked or air/fuel mixture screw is out of adjustment
• Dies under load: Main jet is partially blocked; enough fuel to idle but not enough when the engine is under demand

Simple Home Checks First

Before assuming it's the carby, rule these out:

• Fuel age: If the fuel is more than 4–6 weeks old (especially mixed with ethanol), drain and replace it first
• Spark plug: Pull it and check. If it's black and sooty, the engine is running rich. If it's white, lean. A normal plug is light tan to grey.
• Air filter: A clogged filter causes rich running — the engine gets too much fuel for the restricted air. Clean or replace before anything else.

If It's Still Playing Up — It's Probably the Carby

The giveaway is fuel varnish. Pull the carburettor bowl (or the carby itself on a diaphragm-type unit). If you see brown or yellow residue, sticky deposits, or a film inside the passages, that's old fuel gum. It only needs one small jet blocked to cause all of the symptoms above.

A carburettor service at Gotcha Mowers starts from $65. We strip it, clean it ultrasonically, inspect all jets and the float valve, replace gaskets and O-rings, and set idle and mixture correctly. Most jobs are done in 1–2 days.

When to Replace Instead of Rebuild

Some carburettors are beyond economical repair — particularly cheap pattern carbs on budget machines, or anything that's been run on water-contaminated fuel for a long period. We'll tell you which situation you're in and give you the cost difference before proceeding.