1995, 115 horse Johnson

[tsubaki]

Got a carbed 1995 Ocean Runner that starts cutting out after about 30 minutes of warm up time at full throtle.
It acts and sounds like it is either losing gas or spark and breaking down when trying to apply load after idle and/or when running at full throttle.
The problem is most evident AFTER it has warmed up.
We have;
replaced the fuel cell and all hoses and filters from the tank to the motor and the one in/under the cowl
replaced both coils
replaced the spark plugs as to the book gap/specs
cleaned/rebuilt carbs

It runs, idles and purrs like a dream for the first 30 minutes and then starts acting up.

Any ideas????

[macojoe]

power supply, been there done that, just need to figure out which one? Most say charge both at the same time. I did one at the time as I was too poor for two.

[spareparts]

run on a portable tank, when it acts up. squeeze the bulb, if it doesn't get any better, then its probably the power pack

[tsubaki]

Thanks guys!
Also failed to mention it's a 60 degree looper, fuel mix motor, wires cut off at the oil pump and using (new) Champion plugs. This problem most likely existed with the prior owner. The book has the plug types for the '95 and '96 to be different, yet the specs on those engines look the same. It originally had the type for a '96 in it, we replaced with the ones suggested for a '95.
The next target is the crankshaft position sensor then the powerpack, we also did the remote tank test (different hose and bubble) but not actively pumping the bubble (need to back up and try again).
This motor performs great when attached to a hose and the first 30 minutes of running. After it has warmed up, it (intermittently) idles like crap, acts as if it either loses spark or fuel when put under a load or when at wide open throttle.
Any other ideas, keep them coming.
THANKS

[nymack66]

I am not sure if this engine is equipped with the SLOW feature , if the engine is overheating it will activate and shut off firing on some cylinders..Remove the T-stats as test ..
This year also has a diode in the harness..
Test for SLOW
Engine will not rev beyond 2500 RPM:
1. Use a temperature probe and verify that the engine is not overheating.
2. Disconnect the tan temperature wire from the pack and retest. If the engine now performs properly, replace the
temperature switch.
3. Make sure the tan temperature switch wire is not located next to a spark plug wire.

Simply test also hook four of these in line and run the engine gives you a CLEAR visual if you firing intermittently or not during the symptoms
http://www.harborfreight.com/cpi/cta...temnumber=4424

[tsubaki]

Thanks ny.
No indications of overheating or oil deprivation from sensors or the like.
This is an intermittent pause of engine rpms much like loosing fuel very quickly or an ignition breakdown, but only after completely warmed up. No dropping to low rpms as if overheating or low oil like the SLOW system was intended.

[THEFERMANATOR]

60 degree loopers didn't have many powerpack problems with them, but the optical sensor is known to cause issues. Also be certain to get the cover back on the flywheel for the optic sensor as any light WILL cause false readings in it. It's also not a good idea to run these engines with the cowling off due to the optic sensor getting falso readings from light that gets under the cover. Do you have a PRV meter? If so I would check the stator when it is acting up. Also get you a timing light and make sure to mark the flywheel for TDC on each cylinder on it. When it acts up take your test light and connect it to each wire and see which one is losing spark or jumping time. If it is all of them I would say it is the optic sensor.

[tsubaki]

THANKS Ferm!
I'm assuming the optic sensor is the crank position sensor (gotta help me out here, if not, let me know).
Only 1 run was attempted without the cowl on, the transducer sprayed water, that defeated that. Haven't removed the cover to the sensor over the flywheel (waiting for the part to arrive).
How in the Devil is it light impulsed?? I figured it would be magnetic.
And what in the world is a PRV meter, man, I've been out of the loop a while!
Do have a timing light though!

We are about to the stage of just replacing parts till it stops acting up.

[THEFERMANATOR]

Yep the crank sensor is an optical style instead of magnetic like older engines were. It reads a light signal which has deviation across the RPM range than magnetic sensor's do. PRV= peak reading volt meter. You need one to properly diagnose a magneto as they produce large power spikes and you want to read the highest part of the peak.

[tsubaki]

Thanks FERM!