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Discussion Starter · #1 ·
70 Hp Johnson runs perfect wide open, couldnt ask for a better motor for a 1976 boat. Only issue im having is at idle it will eventually spit and cut off, When trolling with the boat just bumped in gear and idleing down the lake it will run a little while, then spit and cut off, crank it back, it will run, then spit and cut off, I expect it is fouling the plugs, is there something i can do to clear it up where it will idle fine.
 

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try turning the idle screw up just a half turn run wide open for a min then try to idle it down again let me know if that dont fix it dont sound like plug issue as it would run like crap on start up to i would think
:wink:
 

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Well you have the right plugs and you have the good carbs. Look on the side down at the bottom of the carb and you should see a big like brass screw that is hex head and also has a slot in it. Take it out and run you a little piece of wire up through it to see if you have any obstruction in it and also run some sea foam through the system als. You more then likely have a low idle sneeze which sounds like a spit and can be cause from the throttle plates setting open while at idle. When was the last time you did a sink and link on it and has the carbs ever been rebuilt.

One of the first basic things that need to be done here is a spark test and a compression test.
 

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Discussion Starter · #8 ·
Well you have the right plugs and you have the good carbs. Look on the side down at the bottom of the carb and you should see a big like brass screw that is hex head and also has a slot in it. Take it out and run you a little piece of wire up through it to see if you have any obstruction in it and also run some sea foam through the system als. You more then likely have a low idle sneeze which sounds like a spit and can be cause from the throttle plates setting open while at idle. When was the last time you did a sink and link on it and has the carbs ever been rebuilt.

One of the first basic things that need to be done here is a spark test and a compression test.

OK is the brass screw at the bottom of each carb, or at the bottom of the whole setup, run seafoam through the system als? whats als? and the low idle sneeze you described sounds to be exactly what its doing. What is a sink and link? and i believe the carbs were rebuilt 3yrs ago, just before i bought it. I appreciate you guys help.
 

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Hunter, a link and sync is like the timing for an automotive engine. You really need a manual for your motor to do this type stuff. If you have a public library close to you, they may have the manual and you can get the pages you will need xeroxed. I hate to say carbs should be rebuilt at a certain element of time, as time has very little to do with the dirt and gum that's inside them. It may be that three years is okay on yours, it may be they are on the verge of being dirty.
 

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Time has everything to do with it, if gas was left in the carbs.

If not, then the carbs may never have been properly adjusted. It could be as simple as that.

They need to be adjusted on the water, in gear. unrestained, and at idle speed.

Start by screwing in one of the adjustment screws, and "COUNT" how many turns it takes to lightly seat it. It should be near 1 1/2 turns. It could be 2 1/2 on some models to seat it. All 3 should be near the same.

Now preset them ( counter clockwise)all to the same settings + 1/8 turn. Put it in the water, in gear, and start to adjust, one carb at a time Start by screwing the air bleed adjustment screw clockwise, 1/8 turn at a time. Wait 15 seconds, then do it again. Soon you'll notice the sneeze/cough condition. Now back it out until you get the engine to smooth out, then go to the next carb and do the same.

Did I say you'll need someone to drive the boat while you do this?
 
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