2006 Yamaha 150 2 stroke

[Ed99651955]

6g4 x 1013735 n at top 150txrd

[Ed99651955]

I am letting you how its going .I took gas tank out of boat had it clean. I have new gas line new pump all Yamaha. I reset all the spark plugs to .35 I clean the filter on the motor. The boat started out running great ran for 5 miles stop and fish when I crank back up ran fine another mile fish for hour or two when I crank up it like it did not have the power to get the boat on a plane

[Ed99651955]

After waiting a few min the boat crank up and ran fine back to the landing

[rodbolt17]

TXRD should be an 05 model.
that system used 2 pulsers and a crank position sensor to generate 6 sparks.
lose an ign coil and you lose a cyl.
lose a CPS and you lose 2 cyl's.
lose a pulser and you lose 4 cyl's.
the plug caps are also resistive,if one or more fails that ECU can get stupid.
however
I have been working on Yamaha motors mostly exclusively since 1998,started as the only tech at salty dawg and we had over 300 Yamaha's of various sizes.
in 2005 I went to Joe's marine and we have almost 400 Yamaha's of various sizes plus the boats that come in on trailers.
that being said.
I could take all the ign coils,ECU's, CDI's and CPS units that I have replaced since 1998 and place them all in a shopping bag and walk away with it.
first you must understand how and why the system works.
then a systematic trouble shooting must be done.
some years back I made up an "octopus" harness. I soldered six paper clips onto six wires so I could insert them in the coil bullet connectors or back probe any other connector.
I would start by testing CDI output at the point of failure. all six should be about the same.
if they are all in spec your done testing the ign system other than plug caps.
see how easy this stuff can be?

[Ed99651955]

Ok thanks this motor kicking my but

[Ed99651955]

I ran a compression check on my motor and I have one cylinder that has about 30 pounds less compression could that be my problem with my motor dropping a cylinder once in a while if I put a hotter plug in that cylinder would that help

[99yam40]

different plug will not help low compression

[Ed99651955]

You did not answer my ? Do you think 30 pounds off of the one cylinder could be the problem took my boat out today it ran great I did take crank sensor off and clean it

[TownsendsFJR1300]

What is the compression in ALL the cylinders please..

[99yam40]

30 psi difference is bad.
they should be within 10% of each other

that cylinder is on the way out, need to find out why it has low compression
carbon sticking ring can be fixed, but scored cylinder,melted piston, broke ring can go down hill fast

[Ed99651955]

100 on all but one it has 70

[Ed99651955]

Look like this motor has been repaired before I got it used

[Ed99651955]

Do you think I need to take the head off and take a look at the cylinder

[99yam40]

bore scope down the plug hole may help see what the cylinder and top of piston look like,
or pull the head

[zenoahphobic]

Do you think I need to take the head off and take a look at the cylinder

Yes borescope first.
But I don't think a damaged cylinder would cause quite the symptoms you describe; it would not come good again. Even a sticking ring would be unlikely as they rarely occur in isolation, and a borescope is unlikely to show you this.
Prima facea the symptoms are fuel or ignition related, but that is not to say that the internal parts of the engine are worn and need attention.