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Tohatsu 115A2 rough idle, etc.

C

consie67

New member
OK New here. Just picked up a nice 2005 Tohatsu 115 A2 2-stroke. Motor was stored on it's side for 6 months so I primed the F/W separator with pre-mix fuel in case the pump was dry. Fired right up & sounded good but after I shut it off and fired it again motor starts but has big rough hitch to the idle and won't take throttle. Is it in "get home" mode or did I foul it with the pre-mix? Changed the plugs - same deal. Any tips much appreciated.
thanks CC
 
Could be a lot of things. Running the 50:1 in the fuel didn't hurt anything. Get a Factory service manual from any dealer (including me), and start diagnosing, paying particular attention to the fuel system.
 
OK. drained carbs & flushed fuel filter & lines. Fresh gas direct to carbs-same deal. BTW multi function tach wiil flick on when cranking but goes off when motor starts. This unit may not be hooked up correctly. Will this cause the motor to be in "safety" mode?
 
It could cause a lot of things by feeding back to the motor, but it probably just has a poor connection. Is it a Tohatsu tach?
 
Yes, Tohatsu multi-gauge tach. We have all of the obvious push-on connectors tightly together but there are couple of random wires remaining loose. ( we are trying to rig & run this motor after others removed it from another boat) Trim working fine, motor starts right up but goes into this jerky idle mode and will not take throttle.
thanks for any ideas.
CC
 
Start at the beginning. Grab that Factory service manual, and go through the entire rig, confirming everything is properly connected. If the tach is not running, either it's broken, or something else is wrong. That may well be the cause of your poor running as well.
 
thanks Paul. Is it true that the motor "wants" the tach & warnings to be on? The tach does flash on when cranking & then goes out when she starts. Part the trouble is that there are some "non-factory" wires from previous riggers. The tach may not be grounded right or some such.
CC
 
Tach or not, the motor should run fine. d/l a copy of your owner's manual at http://www.tohatsu.com/tech_info/own_man_pdfs/Toh115A2.pdf and verify the rig by using the schematic at the end of the manual. A poor ground could indeed lead to your symptoms, especially since you did have it running properly once. That might well be why you have tach issues too. Could even be a bad connection at the RC box. Likewise, some garbage in the fuel system may have been pushed into the carbs, leading to similar problems. If the motor is in "limp in" mode, you should see or hear a warning lamp and/or buzzer, triggered by either low oil, overheat, or over-rpm indication.
 
I got the service manual. I has a proceedure to test the low rev mode and the warning alarms. The problem is that I still have a couple of wires, (red, black) that I'm not sure where they should go. I'll run the tests.
 
I found the warning buzzer in a box that has red & orange leads with black stripes on them. I plugged this into the O/R lead and a red. Now when I turn the key, the buzzer chrips and the tach comes on & holds at 00. It has gotten dark out now so I will try & start it tommorrow. More than a bit hopeful now.
 
You will need to verify the entire wiring schematic to make sure you are rigged correctly. A pain, I know, but you need a solid foundation to continue any meaningful troubleshooting.
 
OK. Igot it. After testing all of the sensors per the manual, it looked like the CDI was bad. When I took out the CD, I found that the orange/red wire had been crimped and was nearly separated.Spliced the wire and boom, started right up.
Now for the sea trial problems:
1). Motor won't shut off when I turn the ign. key off, (tach goes out & idle goes up a little), I have to pull the clip to shut it down.
2). 3 hours later, motor stared up but shut down like out of fuel after 2 min. I managed to keep it running by pushing in the choke/primer just when it was about to stall. After 2-3 mins it like warmed up and ran OK. Air temp 72, water temp, 64. What's that?
Thank for all the great tips.
Cons
 
If the key won't kill the ignition, there is either a problem with the actual key switch (occasionally happens), or (still) a wiring problem (likely), or a bad CD box (not as common).

Did you run the ohm meter tests on the CD, using a good Analog meter of no more than 3v?
 
Thanks Paul. Yeah, the wiring is still a bit untidy. I'll pull off the lanyard for now. Did not test the CD, as motor runs so well. Installed the right pitch prop today, 5800 RPM trimmed up.
Cons.
 
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