79 70hp Johnson- dying at idle speed

cmorin

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Mar 28, 2004
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I can't seem to solve this nagging problem. Motor:79 70hp Johnson Seahorse. <br /><br />Description of Prob: Starts fine and idles in neutral fine. Runs at full speed great but it bogs and stalls sometimes if you go straight to full throttle. The real nagging problem is encountered at the lowest idle speed in gear. It will idle for a short time and then slowly die out. Sometimes it dies in several seconds and sometimes it goes a minute or so before choking out. <br />What's been don so far: Mechanic changed plugs and cleaned carbs, checked compression, spark, etc. and thought he found prob with pieces of rubber from fuel line in carbs- cleaned carbs and replaced lines, but problem still persisted when I took it out. I brought it back and he researched it further- said dealer told him this vintage had carb problems that came out in a service letter/recall in early 80s where something in carbs vibrated loose and Johsnon recalled carbs. Dealer told him changing the timing or vacuum (I'm not technical but he showed me that he moved the small white wheel back off the linkage about 1/2 inch) slightly smoothed out the problem and was a cheaper alternative to 3 new carbs. So, he made this adjustment but it didn't seem to solve prob. Another mechanic suggested bad thermostats.<br /><br />Help? DO I need new carbs? Can you even find them for this motor? Fuel pump possibly? timing sticking? <br /><br />Coud it be something that's been overlooked? Any technical thoughts would be VERY MUCH appreciated. Thanks in advance!
 
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