Hoping someone can help me out on this, I have an early '90s vintage 50hp Mariner 4-stroke. I'm having an issue with excessively high idle (>2000RPM).
The symptoms:
- On cold start, or left idling for a while, will sometimes sit at 1200-1500.
- After running under load and slowing to idle, idle will "stick" at up to 3000rpm. After a minute or two, often drifts down to ~2000rpm
- Restarting the engine can cause idle to come back down to maybe ~1200-1500 when it is stuck excessively high. Sometimes i will just strobe the key between off and on to bring revs down so I can shift into gear
Circumstances around issue developing:
- Motor previously idled great. Rock solid at ~900RPM
- Recently, the voltage regulator failed, causing voltage to go up to ~18+ volts.
- Idle issue developed at same time as voltage regulator failure. Problem has existed ever since, despite installing new voltage regulator and correcting this issue.
What I've tried:
- I've tried adjusting idle screws and inspecting linkages, etc.
- I've adusted the idle screw. This helped by bringing the idle from ~3500 to ~1500-2000. I can turn it down slightly more (its basically backed out all the way as is) but then the motor stalls (theres no middle ground between stalling as soon as you put in gear and 2000rpm in terms of idle adjustment)
I suspect this may be some sort of ignition timing or electronic component issue. I don't think it has a mechanical cause seeing as it developed at same time as a voltage spike and mechanically everything seems fine.
The symptoms:
- On cold start, or left idling for a while, will sometimes sit at 1200-1500.
- After running under load and slowing to idle, idle will "stick" at up to 3000rpm. After a minute or two, often drifts down to ~2000rpm
- Restarting the engine can cause idle to come back down to maybe ~1200-1500 when it is stuck excessively high. Sometimes i will just strobe the key between off and on to bring revs down so I can shift into gear
Circumstances around issue developing:
- Motor previously idled great. Rock solid at ~900RPM
- Recently, the voltage regulator failed, causing voltage to go up to ~18+ volts.
- Idle issue developed at same time as voltage regulator failure. Problem has existed ever since, despite installing new voltage regulator and correcting this issue.
What I've tried:
- I've tried adjusting idle screws and inspecting linkages, etc.
- I've adusted the idle screw. This helped by bringing the idle from ~3500 to ~1500-2000. I can turn it down slightly more (its basically backed out all the way as is) but then the motor stalls (theres no middle ground between stalling as soon as you put in gear and 2000rpm in terms of idle adjustment)
I suspect this may be some sort of ignition timing or electronic component issue. I don't think it has a mechanical cause seeing as it developed at same time as a voltage spike and mechanically everything seems fine.