# Briggs & Stratton 18.5HP- no start



## snyperj (May 27, 2006)

Hi- I just found this forum today and hoping I can get some help.

I have a Murray garden tractor (46570x8A) with an 18.5HP Briggs & Stratton engine(42A707). The engine will crank but won't start.

Here is what I have attempted so far:
Two new plugs, gapped to mfg specs
New air filter
New fuel filter

In the Murray troubleshooting chart it says to take the spark plugs out, try to crank the engine a few time and then re-install the spark plugs. It didn't change anything but I did notice that the engine seemed to crank exactly the same way without the plugs as it does with the plugs. I am wondering if that means that there is no spark? But I don't really know (or how to test to see if there is). 

I could really use some advice. Thanks!


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## truenorth777 (Mar 28, 2006)

The best way to see if there is any spark on an engine is to remove the plugs and ground them to the engine (metal) make sure that you ground it because you could cause damage to the ignition if it has points.

Next thing to check is for gas on the plugs after cranking the engine over if the plugs are wet with gas than the problem is probibly electronics.. but if they arent wet it is a gas problem.

If you have a gas problem than do a rebuild on the carb and go from there.

Hope this helps.


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## truenorth777 (Mar 28, 2006)

Oopse looks like two posts went in accidentily.


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## bugman (Aug 12, 2004)

Yes, check for spark like given above. No spark? pull the kill wire on the coil.... if you get spark, then you have a bad kill switch. If you still get no spark (if the engine was made after 83 it has no points) its probablly the coil.


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## snyperj (May 27, 2006)

Help me out with this:
"The best way to see if there is any spark on an engine is to remove the plugs and ground them to the engine (metal) "

I can remove them, easy enough, but can you give me more detail on how to ground them? Then what, cranl the engine and look for a spark? 
(I have never done this before)


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## kbalona (Apr 27, 2006)

just touch the tip of the plug against any metal part on the engine. When you crank it over, you should see a spark jumping from the round center electrode in the plug to the side electrode. (the curved part).


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## kollinsb (Jul 25, 2005)

If it were me I'd spray some carb cleaner down in to the carb and then try and turn it over... If it starts and then quits it's a fuel issue and the carb should be rebuilt...


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## truenorth777 (Mar 28, 2006)

1).if you have a two cylander model remove both or the engine can and will start up.

2.after removing the plugs place the back of the plug into the boot (where it originally plugs into) 

3.have a friend or family member crank the engine over for you so you can see if there is any spark between the plug and the electrode (in the gap)

4. you should also hear a distinct snap when cranking it over but make sure you dont touch the metal of the plug or you will get a good zap which feels really weird.

Picture of plug here for more clearness

http://www.aa1car.com/library/sprkplg2.htm

If you need anymore help just post.


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