String Trimmer won't start

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  #1  
Old 06-24-03, 11:30 AM
kylej
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Question Weedeater Stihl FS 52: won't start

I've put new gasket and new piston rings in my weedeater. It's about 10 yrs. old. I've put a new CJ8 spark plug in it with a .20 gap in it; still it won't start. I'm ready to choke it. Sparkplug, compression, new gas with a 40:1 ration---what else can I do???????? Thanks Kyle J.
 
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  #2  
Old 06-24-03, 01:13 PM
Joe_F
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If you squirt some fuel in the chamber will it fire and run?

Have you made sure the muffler isn't stuffed with carbon?
 
  #3  
Old 06-24-03, 02:05 PM
kylej
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I have squirted carb and choke cleaner in the top of the piston (I took the spark plug out). It will not fire, not even turn over. The muffler is not stuffed with carbon. Kyle
 
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Old 06-24-03, 10:04 PM
Ron Hatinger
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With the spark plug out but still attached to the sparkplug wire, pull the rope and see if you are getting spark. Have had new plugs that were bad or the wire that kills the spark running from the stop switch to the coil could be shorted to groud.

BE CAREFULL No FUEL or GAS is SPILLED when checking for Spark in this manner.

Keep is up to date on your findings.

Ron H.
 
  #5  
Old 06-24-03, 11:49 PM
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Hello kylej!

It wont turn over? As in you can't pull the pull rope? Or do you mean it won't try to start? If it turns over fine, then I agree that you should check for spark.
 
  #6  
Old 06-25-03, 08:24 PM
kylej
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Yes, I can pull the rope.....no, it won't fire.....I'll pull the spark plug and check for a spark like Ron said to do
 
  #7  
Old 06-28-03, 08:33 PM
kylej
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Hey Ron....or to anybody else.....If I do have fire at the spark plug, then what should I look for???? If I don't have fire in the spark plug.....then what should I do??? Thanks Kyle
 
  #8  
Old 06-28-03, 11:11 PM
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If you do have spark, it should run with a squirt of gas in the plug hole, unless the compression is bad or the muffler is clogged, which you say is not the case. If you don't have spark, you need to check the kill circuit to the coil.
 
  #9  
Old 07-04-03, 07:11 AM
kylej
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I didn't see any spark when I pulled the spark plug and then pulled the cord.......but I did feel the spark when I pulled it? Now what do I need to do??? I'll probably put a little carb and choke cleaner in the top of the piston and see what happens... I'm about ready to give up on this. KyleJ
 
  #10  
Old 07-04-03, 08:03 AM
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Originally posted by kylej

"but I did feel the spark when I pulled it?"

kyle. Question to you to help us out.

Kindly explain what you mean by "feel the spark?"

You mean as in a shock of current to your self? You felt current?

If so, than there is a spark. May not be highly visable in bright sunlight etc. The point here is to simply determine if there is a spark or not.

TIP:
May need to again change the plug, increase the gap to .30 or .35 from .20 for the test.

You asked: Now what do I need to do???

You need to use the 2 cycle fuel in the test to determine if the engine will start. Carb & or choke cleaner not a good method. Use fuel in the cyclinder, re install the plug and retest.

Than post back the results.

Engine diagnostics is a step by step process to help determine the cause. Many factors must be considered. A few are below.

Compression is a must, insuring fuel is getting out of the tank and to the carb and than out of the carb. There is spark to the plug. The kill switch is not grounded. The plug is wet with fuel when removed after testing by cranking the engine, etc. etc.

You stated: I'm about ready to give up on this.

Stick with it and do so in a step by stpe method as suggested by the pros in the forum. One step at a time and post back the results each time. Together we can resolve the problem...

Regards & Good Luck.
Web Site Host & Small Engine Forum Moderator. "Accurate Power Equipment." Small Engine Diagnostics Services & Repair.
 
  #11  
Old 07-04-03, 11:43 AM
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I agree with Sharp Advice.

Also, it is possible to feel the current, but still not have spark if the coil is weak, plug is bad, etc...

You need to have a visible spark. If you don't... there is the problem. Make sure the metal of the spark plug is touching metal on the engine when checking for spark.
 
  #12  
Old 07-07-03, 08:31 PM
kylej
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I pulled in the dark.........no visible fire....I'll go from .02 to about 30 thousandths and then hopefully will be able to see a spark.
I don't know if the kill switch is grounded or not. Also, I feel the current, but still not have spark....how do I know if the coil is weak, plug is bad, etc...
Why does the metal of the spark plug have to touch the metal on the engine when checking for spark? Can't I just look for a spark where the electrode is and see a little spark between the gap?????? Thanks KyleJ
 
  #13  
Old 07-07-03, 10:30 PM
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No, you can't. That's the reason I said it has to touch the metal of the engine. The magnetic field that develops in the coil when the magnet on the flywheel goes by collapses electronically at a certain time. When this happens, the energy is sent out the coil wire to the spark plug. This energy will go nowhere unless it has a path to ground...in other words, a complete circuit. The engine is the negative isde of this current, the coil holds the positive side of the current. when the plug is touching metal, the electrode of the plug becomes the negative side of the circuit. The anode of the plug is the positive side. When current is sent through this circuit, it is enough current that it jumps through the air in the plug gap to the negative side. If there is no negative side near enough, it can't jump, so it goes nowhere. Just like you can't connect a light bulb to one wire from a battery....you have to have positive AND negative wire for the bulb to light.

The plug must be touching the metal to see any spark at all. Whe you hold the plug and feel the current, the positive side of the coil is using you for a path to ground instead of the metal on the engine.
 
  #14  
Old 07-08-03, 12:37 PM
kylej
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Hey cheese........I do have fire......so now it must me the carb...it probably needs cleaning.....or a new diafram--diaphram (however you spell it). kylej
 
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