backfiring but no start

lilyduck

Cadet
Joined
May 11, 2005
Messages
11
69' 25hp Rude...Solved the problem of getting the gas into the float...replaced fuel filter...Plugs fuel lines and kill switch...Has began to backfire now...Replaced a plastic peice on the underside of the recoil that rotates the flywheel...Question is that after I have pulled a few times the recoil seems to freeze up like itsx to hard to pull...Is that the compression is covering up the hole making it almost impossible to pull...Is the reason that its not firing is becasue the carbs need to be cleaned? or is there something that I'm missing...Anythgin is greatly appreciated, sorry if I havent explained anything correclty I'm new to this.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: backfiring but no start

Loud backfire through the exhaust indicates timing waaaaay of. Often it is because the plug wires are on the wrong plugs. Sometimes it is because the flywheel key has sheared. It is not uncommon that the wires on the wrong plugs will cause the key to shear.<br /><br />That sudden resistance you feel on the cord is probably the engine trying to start backward.<br /><br />Good luck. :)
 

DHPMARINE

Captain
Joined
Dec 16, 2003
Messages
3,688
Re: backfiring but no start

Also if the key is sheared,and you replace it without torquing the flywheel nut to spec,you'll have to keep buying more keys.<br /><br />DHP
 

lilyduck

Cadet
Joined
May 11, 2005
Messages
11
Re: backfiring but no start

the guy I got it from said that he took the flywheel off and tightened with a air compressor torque wrnech...Would this be causin that ...You talk about a flywheel key sheared where is this? what doe it look like...I have ordered a OMC book to try to do the work myself is timing somethign that is hard to do?<br /><br />Thanks IN advance
 

lilyduck

Cadet
Joined
May 11, 2005
Messages
11
Re: backfiring but no start

How do I stop the engine from trying to start backward???hahaha...I'm sorry just a novice at this and want to get this thing running...IF it would help should I take pics.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: backfiring but no start

Wait for your manual, duck. Do not mess with it until you read the manual.<br /><br />After that we can help you with specific questions.<br /><br />Good luck. :)
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: backfiring but no start

The flywheel key is squarish shaped piece that sits in a groove in the crankshaft and a corresponding groove in the flywheel. It physically locks the flywheel to the crankshaft. A sheared or partially sheared key means the ignition timing is upset and the engine will either not run, run poorly, or backfire depending on the how much the flywheel has moved. You will find it quickly in your manual when it arrives.
 

Brew2

Chief Petty Officer
Joined
Jan 12, 2004
Messages
427
Re: backfiring but no start

Like JB said....check the plug wires....good chance that they are on the wrong plugs.<br /><br />Good luck!
 
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