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1989 9.9 hp Johnson Fuel Issues

M

mtetreault10

New member
I have an 89' 9.9 Johnson that I've recently done a TON of work on to get back into shape. Now I'm having issues with keeping it running. Here's whats going on.

  • It runs but it needs to be choked
  • If you push the choke in, it dies after a few seconds
  • The Carb was taken apart and cleaned thoroughly
  • Fresh gas and oil (50:1)
  • The fuel line connections leaked a decent amount (due to 20-30 degree temps
)

I can keep the motor running as long as I want but it needs to be choked (1/2-1/3) and it's much easier to control at higher RPMs. I did this until it warmed up and no change.

Any suggestions?!?! Thanks!
 
Re: 1989 9.9 Johnson Fuel Issues

Fuel lines shouldn't leak at all. Fix them and if the problem still persists rebuild the fuel pump.
 
Re: 1989 9.9 Johnson Fuel Issues

If you need to choke a motor to keep it running there is a fuel issue.------------Did you replace the little rubber / plastic tube in the carburetor??---------------That tube can also interfere with operation of the float.-------------What else do you mean by " a ton of work "
 
Re: 1989 9.9 Johnson Fuel Issues

Well the carb was cleaned and reassembled but nothing was replaced. Everything looked to be in great shape. I did however do the modification to the plastic top adding a 6th screw for even pressure, but that shouldn't affect this. By ton of work I mean, redoing the lower unit (water pump, resurfacing water pump seating surface, cleaning etc), water jacket cleanout and new seals, new head gasket and bypass cover gasket. (compression ~95lbs each), new terminals on coils, new plugs, new plastic indicator elbow, new upper water tube grommet, and a couple other little things.
 
Re: 1989 9.9 Johnson Fuel Issues

Having to use the choke to keep it running indicates blockage in the carburetor.-----------------You did check the reed valves I hope.
 
Re: 1989 9.9 Johnson Fuel Issues

I do not remember checking the reed valves. Those are on the underside of the powerhead above the exhaust tube, Right?

I did notice a small puddle of fuel underneath the carb on that flat surface. Would this indicate anything?
 
Re: 1989 9.9 Johnson Fuel Issues

Sorry they are right behind the carburetor.---------Air going thru the carburetor goes thru them before going into the crankcase.
 
Re: 1989 9.9 Johnson Fuel Issues

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Here's a picture of one of the reed valves and what I believe is the problem. You can see the dents in the aluminum. It looks as if at some point a piece of metal took a few spins around inside of the top part of the crank case. Where those dents are in the pic the large one seems to have actually dented the metal in a micron or so. With the reeds on top and looking into the light you can tell it's gonna leak a lot more than the other. This coupled with the fact there was blowback gas below the carb it should be safe to assume this is the issue. And would cause the lack of fuel issue?
 
Re: 1989 9.9 Johnson Fuel Issues

You're overlooking something within the carburetor.

If the fuel pump or leaf plate valves were faulty, choking the carburetor would not result in having the engine continue to run.
 
Update:

I rebuilt the carburetor and the fuel pump. I also honed the surface of the reed plate and made sure the reeds were seating as well as possible. The motor seems to be running a bit better but when it comes to idling it's still not quite there. I can get the motor running and can sustain it without the use of the choke in neutral in the upper RPM's but when I try and bring it down to an idle it just dies without the choke and is pretty much impossible to bring to an idle with it being pretty sporadic near idle.

What else should I be looking at at this point?
 
Clearly there is an issue with fuel if you need to use choke.-------------Perhaps you need to look at spark / throttle synchronization.------------Many people mistakenly believe that throttle butterfy should be open at idle .---------Throttle should be CLOSED at idle.
 
Well I'm not quite sure what your referring to. But, when the throttle is set to start, the roller is dead center on the notch on the cam plate. If i throttle is down it separates and throttling up it begins to touch right before the middle of the roller lines up with the notch. So by that the plate would be closed at idle... if i could get there
 
After ample time for experimentation I was able to set the idle needle correctly and it will idle all day long. This has highlighted another problem... I can't turn it off. There's something wrong with the kill button but I'm fairly sure I have the two leads correctly wired. the black goes to the bolt between the two coils as a ground and the other one connects to the black/orange wire that should do the killing part. Any idea how to get the actual switch off to see if it has corroded leads or something?
 
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