Need help with 70hp Johnson not accelerating

[nim713]

I just got a 1999 70hp Johnson. Took it out for the first time today. I recently changed the plugs and when I go to start it fires right away. It idles around 1200rpm and when I go to throttle up I got nothing really. Rpm went to around 2200 and the boat did little. A couple times it tried to pick up speed but nothing. When I push the choke in it will accelerate and then stall out. Any ideas of what it might be?

 

[lmuss53]

Pinched fuel line, clogged vent? Try pumping the ball while you attempt to accelerate, if it takes off, suspect the fuel pump.You can also try a portable tank with a new hose and see if it does anything differently.

Take the cover off and with the kill switch pulled and the key off, roll the throttle all the way to the wide open position and see if the linkage is opening the throttle all the way.

 

[schematic]

Any alarm going off? Is it overheating? Is it possible its going into SLOW (safe mode)? Does idle remain at 1200 when warmed up?

 

[nim713]

The fuel line isnt pinched off and the bulb is good and solid. I do believe its going in "slow mode" but im not familiar with it. I have no alarms going off. It remains at 1200 rpms after it warms when i put it in gear and go full throttle it goes to around 2800 rpms but only goes about 10mph. I pulled the hood and could see gas sitting in the housing like it over flowed. I pulled the plugs and 2 of them seemed dry or very clean. When i held in the choke it would accel then stall. A couple times the engine tried to get up but then just went back to slow speed. Im just trying to ball park problems.

 

[schematic]

It remains at 1200 rpms after it warms when i put it in gear and go full throttle it goes to around 2800 rpms but only goes about 10mph.

Is this motor new to you? Did it ever run right when in your possession? I'm wondering if you have one dead cylinder and the idle has been maladjusted to compensate...
Best start with the basics and verify spark and compression.

 

[oldboat1]

you comfortable with a 1,200 rpm idle? would generally look for it to idle at about 700 rpms or thereabouts. If you can't get it to properly idle, would start troubleshooting there. Sounds like a user's guide might be useful -- maybe one online. May not be operating the choke, for example -- maybe a primer, and maybe flooding it.

 

[nim713]

It is new to me but ran it on the water the first time yesterday. It starts great and idles the same. Sadley I couldnt run it on a boat before I bought it. It has equal compression of 140 all the way down. The only thing I have done differently is changed out to new spark plugs and disconnected the VRO system because I prefer to mix. Now I will say i went off of what I was told to do to disconnect that be sepereating the 2 wire harnesses. I dont have a system check gauge yet, bought I bought all new controls and cables and wires. When I connected the horn, I dont get any sound at all when I turn the key, so Im not really sure if thats working properly. Dont I need a system check gauge for that to beep, or sound?I have one on order.