70 hp johnson stalls when put in gear

tgaither

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Feb 19, 2017
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I have a 2000 70 hp Johnson runs great in yard but when I put n lake it dies when I put in gear.I have new fuel lines and carbs rebuilt
 

flyingscott

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You need to do a compression and spark test or cylinder drop test. Spark needs to jump 7/16" of a gap.
 

racerone

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Ignition system was designed and built " at some expense " to be able to produce 40,000 volts or so.-------That is able to jump a gap of 7/16" in air.--------Not just the 0.040" of the sparkplug gap.--------That is why folks are asked to do the proper test.-----It seems hard for some to follow good advice.
 

flyingscott

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Your motor sounds like it is running on 1 or 2 cylinders. What is great compression? Try the cylinder drop test. Get a plastic pliers and pull the plug wires one at a time off while it is running. If all the cylinders are firing the idle should change as you pull the plugs off. If the idle doesn't change when you pull a plug wire off or you don't hear a snap from the spark. That cylinder is probably not firing.
 

phillnjack2

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compression on that motor needs to be around 140 to 150 psi. all the oval port motors average around 145 psi, some a touch higher and some down to 140.
anything lower than 135 psi is starting to get a bit worn on those engines.

Now first thing to do is get the flywheel off, these motors suffer with broken wires up under the flywheel., its where the wires bend and go into the stator.
the bend on the wires is terrible and drops a touch and then gets cut by moving parts, youl see it when you get flywheel off.
what I done was managed to join one of the wires with solder then melted some plastic onto it. the other wire I just melted plastic to cover it again.

I had thought it was loads of other things, powerpack rectifier all sorts. stripped carbs about 8 times because it seemed like a fuel problem.
But the broken stator wires is very common.
flywheel on these needs a harmonic balancer and a real good tug in the long bar to crack it free.
below is 2 different stators both suffering the same problem of cut wires.

on muffs the motor seemed absolutely 100% on the river it was a joke and would no way plane.

its worth checking the stator wires anyway. if they are not broke at least youl be able to warm them up and bend them back a touch before they get cut.
flywheel torque is 105 ft lbs. make sure the crank taper is ultra clean with NO oil or grease or lubricant when replacing.

hope this helps.
 

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tgaither

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been working late hours this week. Mechanic who rebuilt carbs said compression great haven't checked myself I intend to try all these suggestions come weekend. Spark plugs are ngk going to replace with champion not sure that will make a difference but I prefer oem parts. If no spark on cylinder does that mean bad coil or powerpack? thanx for the help
 

phillnjack2

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Big difference between NGK and the correct champion plugs. this is the correct plug for your motor Champion QL77JC4 .
you should never put the ngk plugs as they are not compatible with your motor , no matter what a shop tells you.
No spark can mean a few things, but first do check connections everywhere. !!!!
the spark gap jumping of 7/16ths for the plugs to jump is a good indication if the spark is strong enough.
you can easy make a spark jump tester or buy one for just a few dollars.
give the coil leads a good clean and undo the bolts and take the coils off then put back once cleaned around the bolt area's.
I did also do this with the complete plate that holds the coils and other electric's, only takes a small piece of dirt to stop a good ground connection.
and like said above sometimes these motors will run on just 2 cylinders and out of water will sound like plenty of power.
before replacing a coil swap it over with one of the others to double check its not bad connections .

Also do make sure none of the brown wires or black and white wires coming from the temp switch (top left when looking at cylinder head from the prop)
are not touching any spark plugs wires or coil wires, this can give interference in the signal and send the power pack into frenzy.

I had a few issues with my motor and it all was due to corrosion and broken wires, but it kept on seeming like a fuel problem.
.

this forum will definitely get you in the right place, loads of people are willing to help out because most of us also got some good tips and tricks from this very place.
 

kbait

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Nov 13, 2007
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If carb idle mixture screws were adjusted when motor was idling on muffs (no exhaust backpressure), the settings may be incorrect for motor idling in barrel or lake.. if spark/ compression etc is all good, you may just need to re-adjust the low speed mixture needles. Try opening (richer) each needle 1/8 turn or so and see if it helps. You may also have to increase low idle speed stop..
Good luck!
 

David Young

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If carb idle mixture screws were adjusted when motor was idling on muffs (no exhaust backpressure), the settings may be incorrect for motor idling in barrel or lake.. if spark/ compression etc is all good, you may just need to re-adjust the low speed mixture needles. Try opening (richer) each needle 1/8 turn or so and see if it helps. You may also have to increase low idle speed stop..
Good luck!

​I agree. My motor idles around 1100-1200 RPM in a barrel but, in the lake it idles at 600-700 RPM.
 

WIMUSKY

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been working late hours this week. Mechanic who rebuilt carbs said compression great haven't checked myself I intend to try all these suggestions come weekend. Spark plugs are ngk going to replace with champion not sure that will make a difference but I prefer oem parts. If no spark on cylinder does that mean bad coil or powerpack? thanx for the help

That's a good place to start, put in new plugs and see what happens. Could have a bad plug. Might as well do a compression test when you have them out. As far as NGK vs Champion, in all my small engines I use NGK. I don't use Champions in anything....
 

tgaither

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compression is 144,144 143 spark test was good ,pulled plug wires while running,no change when I pulled top plug wire so I removed coil and wires and cleaned all connections when I pull it now there is a difference in idle.did die in barrel when I first tried but after doing that and changing to champion ql77jc4 plugs it does run in gear in barrel now I just have to take it to lake and see what happens.Thanx for the help will let u know what happens.
 

WIMUSKY

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compression is 144,144 143 spark test was good ,pulled plug wires while running,no change when I pulled top plug wire so I removed coil and wires and cleaned all connections when I pull it now there is a difference in idle.did die in barrel when I first tried but after doing that and changing to champion ql77jc4 plugs it does run in gear in barrel now I just have to take it to lake and see what happens.Thanx for the help will let u know what happens.

Sounds like you're figuring it out. You were obviously running on only 2 cylinders. Did it die in the barrel before you cleaned the ignition wires? Then you cleaned the ignition wires "and" replaced plugs and it ran fine? I think that's what your saying.....
 

tgaither

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tried in barrel first before I did anything .Had to wait for plugs I ordered thru oreillys,bought ignition spark tester and borrowed gauge from mechanic at work to check compression.Gonna try to put in water tomorrow will let you all know how it goes.I think carbs will probly need some adjusting and should try to do that on water I think if I can
 

oldboat1

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If the boat is new to you and has a permanent tank, check for fuel contamination. (Use the primer bulb to pump some into a glass jar, and let it settle out -- water would be at the bottom.)
 

WIMUSKY

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tried in barrel first before I did anything .Had to wait for plugs I ordered thru oreillys,bought ignition spark tester and borrowed gauge from mechanic at work to check compression.Gonna try to put in water tomorrow will let you all know how it goes.I think carbs will probly need some adjusting and should try to do that on water I think if I can

That's what I thought. Probably had everything to do with the dead cylinder and not the plugs. Unless one plug looked different than the other 2. Even so it's good to change them, whether replaced with NGK or Champion.... Good luck.....
 
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