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2004 OX66 Intermittent issue

captchad

New member
Hello all! I have searched numerous other forums regarding this issue, and have replaced all which was recommended to me, yet my problem still exists.

I have an 04 OX66, 200hp. The engine will start within 1/2 a revolution in the morning. It will idle at the dock for 10-15 minutes while I wait for everyone to gather their things and board the boat. Ill get out of the no wake zone, get up on plane, and run for about 20 seconds (1/4 to 1/2 throttle), and the engine will fall on its face. Most times it will restart immediately and run as if it was a brand new engine for the rest of the day.

This morning, boat was idling for about 10 minutes, then killed. Took about 20 minutes to get it to start again. Got up on plane, engine killed about 20 seconds later. Took another few minutes to re-start, got on plane, then killed again. Another several minutes getting it to re-start, and I fished for 6 hours after with no issues the rest of the day. Get to a spot, kill the engine, it would restart immediately, then run to my next spot, kill, re-start, run to next spot, etc.

I have replaced spark plugs, low pressure fuel pumps, O2 sensor, New VST filter and gasket for tank, new primer bulb, drained and re-fueled the main tank, added ring-free to fuel, and tried yamalube and I'm now on Penzoil synthetic. Not sure if I may have an ignition or fuel related problem. Just trying to avoid the $125 an hour on an intermittent issue at the repair facility. Any help is greatly appreciated!

Thanks,

Chad
 
Try diagnosing it before replacing more parts. The typical reasons for your issues are:

-lean fuel mixture
-low compression
-weak spark
-electrical issue

Is the cranking battery healthy, and are the terminal connections tight and free of corrosion?

Are there any leaks near the air intake manifold? Spray some brake cleaner or starting fluid near the manifold to see if the idle speed changes.

Remove all the spark plugs. Do the tips all look the same? Can you tell if it's running lean or rich? Look for pictures online to compare yours to.

Get a compression gauge, and test all the cylinders to make sure they're within spec. Warm up the engine, shut it down, remove all the spark plugs, fully open the throttle, remove the safety lanyard, and crank the engine after screwing in the gauge. Get the service manual to tell you what the spec is.

Get a spark tester, and test all the plug wires immediately after the issue occurs. Make sure they all produce good spark.

If none of those tests reveal anything unusual, then it's probably worth taking in to a tech.
 
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