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1997 200HP Ocean Pro - erratic idle RPM

D

dingbat

Member
I fished on Sunday and the boat ran well. I had no complaints at all. Went out Monday morning to flush the motor and it would not idle right. Start it up, it would idle at 1400-1500 RPM then drop down to it's normal 1100-1200 when Quick Start dropped out. After 5-10 seconds, it would jump back up to 1400-1500 rpm and stay there for 15-20 seconds then drop back to 1100-1200 rpm again. Sometimes it will would miss right before the transition from high to low idle, sometimes not.

All fuel connections are tight. Primer bulb stays relatively hard. The Racor fuel filter is fairly new. Maybe 300 gallons of fuel run thru it. The bouncing back and forth between “quick start” speed and idle speed has me thinking it’s electric, not a fuel problem

FWIW: This motor had never idled reliability below 850 RPM. Anything lower than 850 rpm and its hit and miss if it will stay running for any length of time.
 
Re: 97 200HP Ocean Pro - erratic idle RPM

Hi dingbat...
I have a friend over on Iboats who goes by mikesea that has the same issue. You might want to PM him to compare notes.

Anyway, the idle speed on these loopers is set/controlled by changing the ignition timing. Spec says the idle timing should be around 4* ATDC at normal idle speed. So, if it were me, in order to pin down a possible cause, I would put a timing light on the engine at idle. Watch carefully. See if you can get a timing reading when it is idling just the way you want it to idle. Then watch carefully to see if the timing jumps toward some BTDC value as the idle speeds up on you. If the timing is jumping around as you watch the light, there are three main possibilities.

1. Bad timer base.
2. Bad power pack.
3. Bad port temp sensor.

If the port temp sensor is bad, it can be tested by simply disconnecting the white/black wire to the pack.

Another related but unlikely problem cound be the yellow/red wire from the starter solenoid to the pack. If it is getting intermittent +12v on it from a defective key switch or other short, it may confuse the pack and cause erratic idle. I will see if I can re-create this on my boat today and let you know.

I hope this helps, and if you find the problem, please let mikesea know what you found.
 
Re: 97 200HP Ocean Pro - erratic idle RPM

These are the steps I would take -------#1 a compression test-------#2 verify that ignition is firing on all 6 and at the correct time ( make your own timing marks if you have to ) they do not have to be exact----------#3 carburetors are absolutely clean----------#4 verify that sealing rings on the crankshaft are not broken and in good condition ( crankcase compression )
 
Re: 97 200HP Ocean Pro - erratic idle RPM

how is the other,rpm operation----slow,sluggish?...i have the exact same eng,..there is a timer ring problem w/them,...on the flywheel...it comes -un-glued--...and spins,throwing timing off,..mine,..WAS in fact loose.....
 
Re: 97 200HP Ocean Pro - erratic idle RPM

Good point on the timer base magnet ring on the flywheel...
It should still show up as jumping timing when using a timing light.
 
Re: 97 200HP Ocean Pro - erratic idle RPM

Outside of this issue that just popped up, the motor has been running good and strong. I let it idle at the dock maybe 5-10 minuted before I put it on the trailer and the idle was steady as can be. Either this problem doesn't manifest itself in the water or something happened between then and now.
I'll check the flywheel and throw a timing light over the weekend and get back with you.
 
I don't remember if the Fast Start feature, once disengaged, can be engaged again without shutting the engine down or not. If not, disregard the following.

Assuming this problem only takes place when running on a flushette......... When this occurs, does the temperature of the cylinder heads change drastically? (Hands On)

Hose water pressure should be full blast. Thermostats or bypass valves weakened? Water pump drawing air?
 
Could not identifiy the miss with spark tester. Changed plugs. A little better but not perfect. Played around a bit with the idle and got it fairly stable. Still bounces around a bit but only by 50-75 RPM
 
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