50 hp misses at 20mph

[dcmaker100]

ihave a 94 50 hp evinrude 2cyl 2 cycle with oil injection.motor starts idle trolls forever at 2 mph and runs perfectly on both cylinders all the way up to until 19mph.then when you push the throttle one more fraction of an inch it begins to skip.I can repeat this many times and it does it every time.I have replaced the spark control module already.it runs perfectly otherwise.

[boats.net]

At what RPM's does the motor miss?

[dcmaker100]

I dont know but i suspect its around that 2500 mark.Im suspecting the slow is the problem but thats why i purchased the control module.

[boats.net]

Start by varifying that you are loosing spark. If you are loosing spark, you can start testing the ignition system. You will need a service manual.

[dcmaker100]

I have a service manual-SELOC.How do i test for the loss of spark while it is running and what cylinders are affected whan the slow activates if it is that.I will systematically check if you can explain what to do.I performed some tests according to the manual but did not have a peak dvom.I then purchased a coil then a powerpack.thanks for youre help.

[boats.net]

You can check spark with a spark tester or by removing the spark plug wire, if you loose RPM then that plug is firing. If no change then that is a dead cylinder.

[dcmaker100]

both cylinders have spark.it runs perfectly on both cylinders all the time right up untill the time you try to exceed 19mph.

[boats.net]

Need to check each cylinder with a timing light to see if can see a miss on light, probably will need to run a voltage output test on ignition components with a peak reading voltmeter.

[dcmaker100]

s.l.o.w. problem solved

ok the problem in my case was that the new power pak i bought was defective.I replaced it and my poor performance problem that i described at 19 miles an hour went away and the motor runs perfect.now the rest of this post is just personal opinnion.thanks to every one who responded to try and help me with this problem and i love forums like this one that help me solve all kinds of mechanical problems i have with cars,boats etc.but, it seems to me that no one with any real knowledge about outboards is willing to say anything beyond the standard which is buy a manual,purchase testing equipment and try to follow the highly technical electrical directions to bench test every circuit on the motor.while this is the best course of action if you were an actual technition and posessed all the tools and training to carry out theese procedures,i would like to suggest an alternative for those of us who are good novice machanics that have successfully repaired all types of mechanical and electrical issues on cars lawnmowers etc.try to list the most likely possible causes and rank them by probability.for example in my case i described pretty well what i thought was a s.l.o.w. problem.lets face it what other pro blem could occour at such a specific rpm range and be so totally absent at slower speeds?19mph-prefect,20mph-problem.if someone had said there are only three things that will cause the slow circuit to initiate and these are the most likely culprits i would have chose the most inexpensive and worked my way to the most expensive.ther is nothing wrong with an educated guess.and i would rather spend 300 dollars on parts before fixing the right one instead of paying 300 in labor and then pay double for the part that caused the problem.thanx again.