72 125 Jonny Shifts Hard???

jtwood12

Cadet
Joined
Apr 22, 2006
Messages
21
I have stated engine above. This is what is going on. When I'm out on the water and slide the control forward it pretty much slams when it shifts to forward same with reverse.Also when I start the engine it starts in forward till I hit the elec. choke....... Any ideas.... Thanks in advance you guys are great.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 72 125 Jonny Shifts Hard???

how fast are your idle rpms? you probably have and electric shift. they default to forward gear. until started.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,786
Re: 72 125 Jonny Shifts Hard???

I had one for several years; bought new, so it's been awhile.<br /><br />Failsafe on the engine is forward gear so that is the now power to the lower unit position.<br /><br />It's electrically shifted. Sounds like you are loosing power to the lower unit in N. Might get a manual and follow the wiring. May be in your control box as your lower unit knows not that you hit the elec choke.....check for bad grounds (corroded) among other things. The switches that control the solenoids in the lower unit are probably in the remote control and are physically activated by detents on the shift handle...hence how else would it know which one is to be energized. <br /><br />This is why I suggested checking grounds. The two circuits mentioned are independent of one another.....except I'd bet they share a common ground......the case of the remote controller.<br /><br />Should be O ohms, or no more than 0.5 (not counting your meter's lead resistance)to the case of the engine....or the place on the engine where the battery - power cable is connected. All connections need to be clean, shiny, and tight. Take wires off to clean, don't just clean the top. A little vaseline over the terminals and all after you finish will help to keep water out and reduce future events. Don't lube up till after assembly; you don't want grease or oil between the electrical contacts.<br /><br />On clunking, is your prop nut loose? Or are you trying to shift with the fast idle, fast idling? Either will produce clunking....course with a ss prop some clunking should be expected; not like your auto tranny in your car.<br /><br />Best I can do from here.<br /><br />Mark
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,786
Re: 72 125 Jonny Shifts Hard???

Second line error.....now is a typo. Should be NO power to the lower unit in Forward gear.<br /><br />Sorry,<br /><br />Mark
 

jtwood12

Cadet
Joined
Apr 22, 2006
Messages
21
Re: 72 125 Jonny Shifts Hard???

Ok heres were I'm at. I tracked the wires while looking at the wire diagram in the manual and found that the shift diodes on the engine were wired to the terminal wrong so I switched it back to the way the diagram showed. The question is could this cause the motor to start in gear and when I kill it not jump in gear? Also someone said idle to high? dont have a clue the rpm gauge not working at the moment is that also caused by the diode? Also sometimes I will be at WOT and the thing just dies the funny thing is I hit the key and bam there it is again. <br /><br />This motor runs like a champ at full throttle the problem is getting it there with no problems ie. the slamming and starting in gear.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: 72 125 Jonny Shifts Hard???

That motor shifts by hydraulic oil pressure. The solenoids simply divert the oil to different paths. <br /><br />With the motor not running it will always be in forward. Even with the key on and power to one or both solenoids. When the motor runs the driveshaft will operate the hydraulic pump in the lower unit which creates the oil pressure. When you start the motor in neutral one solenoid will have power. That opens a path for the oil pressure to move the clutch dog back from forward and into the neutral position. <br /><br />When in reverse both solenoids will have power to them and the dog will be pushed back to the reverse gear.<br /><br />When you select forward no power will be to either solenoid and the dog will engage the forward gear.<br /><br />If it isn't shifting smoothly the rpm's, as mentioned, could be too high. Or the plunger in the pump could be sticking. Or you could have the wrong fluid in the case.
 
Top