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2001 Johnson 70 (3 Cylinder) Dropping Cylinders While Running?

C

captb

Contributing Member
I had this issue last year and ended up replacing a coil (just got lucky that was what it was when i swapped it) and now I'm having the same problem again. Is it possible that another has went bad? Or, should I start looking else where, like the stater or power packs?

I don't remember there being any visible issue with the coil, so I know I can't just look at 'em and see which one it is. I have, on another motor, be able to "see" which power pack was bad, because of signs of heat.

Thoughts? The symptoms this time, similar to last year, running on plain, maybe 3500 rpm, it'll just die. It'll still push you along, but there's definitely a reduction is umf and the motor sound changes. (this is on my skiff so I don't have a tachometer. I'm just guessing at the rpm's and can't tell you what it's actually dropping to) It'll pick back up in a minute or so and run fine for a while, maybe the rest of the trip. When it does pick back up, it'll throw you in the bottom of the boat!

Thanks, B
 
The ignition stuff is quite reliable.---------------Is the motor running hot and the " SLOW " system kicking in to protect the motor.-------Done a compression test ?-----Run a timing light to see if one cylinder has a problem or all 3.
 
I don't think its running hot. Water pump's less than a year old, and tell tale is strong. No compression test yet. I don't have a timing light.

Any chance it's a carb issue?
 
Done a complete check of fuel system / fittings for leaks ?-----Verified that VRO system is working properly ?------------Water in the fuel ?------------What happens when the manual fuel pump is operated ( primer bulb ) on the hose.--------You can always look into carburetor throats ( strong flashlight ) at full throttle and compare amounts of fuel coming up the main jets when motor falters.
 
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No on the complete fuel system check, but new fuel lines from tank (new tank too) to motor last spring. VRO is disconnected, had it done at a dealer several years ago. No water in the fuel, fuel doesn't set around long enough with me.

Have not tried the primer bulb, but will the next time it does it. I will also look into the carbs next time.

thanks for the ideas.
 
Manual choke stuck in the choked position appears to have been the problem. Nice, cheap fix.


Now I'm wondering why there's an electric choke and manual choke. I understand it, but the electric choke should be reliable enough.

Either way, thanks for all the advice.
 
If the battery was totally dead the electric primer does not work.-------------So you operate the primer on manual mode, and pull the motor over with a rope to start it.------Well thought out design / set-up.
 
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