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1983 Johnson 50hp tiller - stalling?

R

rbecklund

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My 50hp is stalling when I put it under power in gear. If I slowly bring it up on rpms under load it will not stall but if I "gun it" it stalls. I cleaned the carbs and the carbs are sync-ed. There is no slop in the rod between the carbs. I cleaned the mesh filter in the fuel pump also. The primer is leaking when i hit the button so I ordered a new kit for that. Any other ideas? Thanks for your help
 
Welcome to the forum.
Since MN is shoving ethanol down our throats with mandates, perhaps it's gonna need a fuel system overhaul. Was it okay last year? Has it used ethanol fuel before? Maybe you already know what ethanol does to fuel.
 
I don't have a spark jump tool but I did pull the plugs and they had what looked to be good spark. I will try borrow a compression tester today to check that.

I just bought this boat and motor to redo it. I have no experience with this one altho I have a 35hp the same year on a smaller lund fishing boat and have worked on it many times. The fittings on the gas lines you can tell are seeping a little bit and the primer is spraying gas when I hit the primer button. I have ordered a kit for the primer and hopefully it will be here before the weekend. I don't know if the primer leaking would have anything to do with it stalling under power but I am sure it wouldn't help any. I cleaned the carbs (didn't put kits in them) and pulled the jets to make sure everything was clean. It has new gas and oil in the tank as well. I put premium in it, not knowing if that actually matters or not.
 
Did the carbs have signs of fuel residue or oxidation. Beware that some premium fuel HAS ethanol. State law requires that pure petrol (without ethanol) has to display a sticker on the pump.
 
Okay, so maybe it is clean. Boobie been around a long time, check the spark and compression. Always good to know anyway.
 
140 on the top cylinder and 75 in the bottom cylinder. Have not checked the spark jump yet. So when you have a difference like this is it normally head gasket or is it something worse?
 
Here's what happens. One carb partially plugs main jet....... receiving cylinder gets run dry/lean.....the "good" cylinder is "dragging" it around. Lean means lack of lubricating oil too. The motor will still seem to run "okay"......but the piston is "melting" and cylinder scoring. These motors are really susceptible to damage in this way. Ethanol is very destructive when carbs get "partially" plugged up from fuel that actually "invites" trouble. My guess is overhaul time. Be sure to clean that carb and open main jet to correct size. I use welding tip cleaning tool and CRC throttle body cleaner. It's very strong.....keep it off your skin and any painted surfaces.
Here in MN, ethanol is directly responsible for nearly half of all my repairs. Honestly......I cannot tell you how much destruction that oxygenated fuels have caused to older equipment, or seasonal tools and recreational equipment......including diesels......yes it's in diesel fuel too.
 
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took the head off a little bit ago. Head gasket was in pieces but no scratches or grooves in the cylinder. By the sounds of it I am very lucky.
 
I appreciate the advice on getting the head planed. It was very warped according to my machinist. He already had it done before noon which is nice.
 
Racer been around a long long time. Be sure to clean head bolts well and LIGHTLY nickel anti-seize the threads. Why? When assembled at the factory, the head bolts are NEW. That means they are zinc coated....they will resist rust and oxidation. When you remove them after all those years.....that protection is GONE. Use no sealant on head gasket and torque to specs working from the central bolts and alternating towards top and bottom....bringing up torque in small increments.
 
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