Not Sure where to start trouble shooting

Mudboy68

Cadet
Joined
Apr 25, 2006
Messages
18
Hello All,<br /><br />I hope someone may have had this problem before because I'm stumped.<br /><br />I Have a 1970 115 Evinrude electic shift on a 16ft canbar bowrider.<br /><br />I tuned it up in the driveway uning a 45 gallon drum (found cups jut don't do it)and it ran great after setting the link and sync and adjusting the timing advance.<br /><br />Took it out on the lake sunday started great but when I put it in gear it's like 2 cylinders stop working and if I throttle it up too fast it will stall but if I open it up slowly, About half throttle all 4 cylinders kick in and away it goes and it runs great until you throttle it back. If you throttle back too fast it stalls if you throttle back gradually it slows down and at half throtle again it's like it is running on 2 cylinders again if you shift into neutral it Idles and throtles up just fine.<br /><br />I'm at a loss any input would be great.<br />Thanks <br />Brad
 

dc in ms

Seaman Apprentice
Joined
Jan 6, 2006
Messages
41
Re: Not Sure where to start trouble shooting

It sounds to me like midrange jets in carb are clogged ( if it has mid range jets) or maybe it's flooding for some reason at that throttle range. Maybe your choke valve is activating when it shouldn't. Possibly loose wiring causing short??? <br /><br />Good luck
 

Walker

Captain
Joined
Jun 15, 2002
Messages
3,085
Re: Not Sure where to start trouble shooting

I guess carbs too. Tear them down and give them a thorough cleaning. Do a search on carb cleaning
 

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: Not Sure where to start trouble shooting

See if you can recreate the symptoms with it running in the barrel. If so, then pull the spark plug wires one at a time (use a plug wire tool or somebody you don't like too much, to avoid getting shocked). If the RPMs don't change when you pull the wire, that's your problem cylinder. Before disassembling the carb, I'd check for spark - no spark, it's an ignition problem.
 
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