Craftsman 18.5 hard start this season

12 years ago

Have a Craftsman 18.5 with the Briggs & Straton motor.

Broke the plug wire while attempting to replace the plug.

Had to buy a new magneto, cause it's hard wired.

Have the new, replaced the plug and set the mag to .30mm, not the .25mm recommended.

Why you ask?

It's what I have around.

Set it tight, hoping to make up the difference.

Non start....

Is that .05mm really making the difference?

If so, I'm out to buy a new set of gauges.

Sort by:Oldest

Comments (3)

bluemower
12 years ago
The .25 - .30mm is the correct adjustment for most of the briggs. You have not provided very much information, but here are some ideas.

1. disconnect the shut off wire that is attached to the ignition coil Perform a spark test. (ask if you are not familiar with this). you may need to test in a dark garage.

2. If there is no spark, examine the coil to see if it was installed upside down. Also examine the screw post for corrosion. Corrosion could provide resistance and prevent the spark.

3. Examine the new coil to see if it it blew out when the ignition key was turned. Using an anolog meter, look for signs of voltage on the kill wire when the key is turned. If voltage is present, this must be corrected.

4. If the ignition system is ok, look for problems with the fuel system. Low compression or mistiming could be a problem
olddawg
Original Author
12 years ago
Thank you for the response.

I did check for spark, good

Magneto only goes one way and did clean the mount before install

Your third I'm uncertain about.
Would there be any power in a magneto before the head turns?

I've been leaning towards the mis-timing, but being a single cylinder, magneto arrangement, I assume the piston alines as the head passes the magneto.
Each turn of the head equals a full cycle of the piston.. No?

I'm getting a popping sound, being the gas burning.
I drained the tank and added fresh fuel.
I went as far as adding fuel stabilizer (what I do in the snowblower when it's hard to start).
bluemower
12 years ago
your comment
"Your third I'm uncertain about."
============================================
I was referring to the possibility of a failed new ignition coil. The magneto ignition coil should never receive voltage from a battery source. Sometimes, the ignition switch fails - and sends battery voltage to the coil. This burns the coil out instantly.

The reference to timing concerns a failed flywheel key. In this situation, the position of the flywheel shifts in relation to the crankshaft. On a magnatron ignition, the coil will still fire - just at the wrong time.

If the ignition system is working and the flywheel key is ok, your problem is probably related to low compression or the fuel system or old fuel. The after fire solenoid (if equipped) should also be checked. Did you examine the choke for adjustment?