Small Engines (Lawn Mowers, etc.): Tecumseh 5 hp, twin cylinder engines, fuel air mixture

Question
I have a tec 5 hp motor on a go cart that is giving me trouble starting.  It is roughly a year old.  It will start with starter fluid and continue to run after that.  It doesn't idle smooth and surges while running.  Do you think I need to put a needle and seat in and give the carb a good cleaning to fix the problem?  I haven't checked compression but do not have any reason to think that is an issue - no smoke.
Thank you for your thoughts.

Answer
Micky

The reasons for an engine to be hard to start can be caused by a wide variety of individual or combination's of concurrent problems and the best place to begin is to do a quick check of the engine:

   * Is the tank full of fresh gasoline?
   * Does the air filter need to be cleaned or replaced?
   * Check the condition of the spark plug.
   * Is the fuel valve turned on?
   * Is the On/Off switch turned ON?
   * Is the choke in the correct position or the primer functioning?
   * Check the oil for correct fill level and quality. *(see note below)

If the problem isn't located or resolved during the quick check procedure, you'll need to check for the following problems:

   * Improper fuel/air mixture reaching the carb
   * Weak spark
   * Improper timing
   * Low Compression
   * Not turning fast enough to start
Engine surging can best be described as the condition where the engine RPM fluctuates repeatedly from high to low during operation. More often than not, this type of problem will be caused by a dirty fuel system or intermittent ignition spark.

Here are some general guidelines that may help in the troubleshooting process:

Engine Surges at ALL Speed Ranges

Common Causes:

   * Dirty air filter.
   * Water or trash in the fuel system.
   * Breaks in the spark plug wire, loose or corroded terminal connections causing an intermittent failure. (Very common for twin cylinder engines.)
   * Misadjusted or malfunctioning governor. (see note below)


Engine Surges at Idle Speeds or Top No Load Speeds

A common cause for this situation is an incorrect fuel mixture or blockage affecting the idle circuit of the carb. Most carburetors on small engines operate on the idle circuit of the carb at all speed ranges except when the engine is under a work load so you might try adjusting the idle mixture screw on the carb as a possible solution.

Engine Surges Only While Under A Work Load:

A common cause for this situation is an incorrect fuel mixture or blockage affecting the main circuit of the carb. The main circuit of the carb is used primarily when the engine is under a work load, so if you have an adjustable carb, you might try adjusting the main mixture screw as a possible solution.