Specifications

Compression Test a Weed Eater Engine

If a Weed eater has trouble starting and all the usual troubleshooting routes

have been explored then the issue may be poor engine compression pressure.

The usual non-start routes include gas, fuel lines, carburetor, air filter and

spark plug. The piston in the weed eater engine has piston rings that prevent

the combustion chamber pressure from escaping past the piston and into the

crankcase. Furthermore if the engine cylinder’s valve is not seating correctly

then air may be passing by the valve and into the carburetor. A simple check

with the aid of a compression tester can determine if the weed eater is not

starting due to poor pressure. For weed eaters the compression pressure must

be greater than 60 lb. per square inch or PSI. If the pressure is less than 60

psi then the cylinder is loosing pressure and the engine will not start. If this is

the case then the engine will only ever work again if it is reconditioned

replacing piston rings, valves and valve seats.

Unfortunately it is cheaper to buy a new weed eater then reconditioning your

existing trimmer engine. However a compression test conducted by yourself

is a very cheap and effective way to troubleshoot the problem and save you

time and money replacing other parts thinking you have a traditional non-start

problem. At the very least you can eliminate the possibility that you have poor

compression pressure.

Follow the listed steps below to conduct a compression test on a Weed eater

Engine:

Safety: Do not forget to use safety glasses and gloves

1. Ensure that the weed eater is off and not running.

2. Remove the spark plug cap located on the engine.

3. Remove the spark plug with the aid of a spark plug socket wrench.

4. Purchase a compression tester or borrow one from someone else.

5. Push the free end of the compression tester hose into the recess that the