1993 Yamaha 150 HP Alarm issue and runs rough.

[bluewaterDevil]

I am stumped seems like an electrical issue!

Motor Runs great good compression, but when I run wide opened the:

1. Alarm goes off
2. The motor runs like crap and it starts running like your running a ground (really rough almost like only 3 cylinders are running).
3. Water temp is good, newer impeller, water flows great.
4. Motor starts first crank after it?s warmed up, but on the initial start up she needs to be choked.

I know one of my batteries cell is dead and I am thinking it could possible be a volt issue.

Any insight would be greatly appreciated.

 

[jeffersondodson561]

Re: 1993 Yamaha 150 HP Alarm issue and runs rough.

Check spark on each cylinder, Yamaha spark is really hard to see. I know people are you going to argue me on this, but if you take the plug and hold it against the block and crank over the engine and witness spark you you have spark. I know you are supposed to use a spark checker but you pretty much need to be in shaded area to see Yamaha spark. You will probably need to invest in a DVA to test ignition components. Once you get it check the primary voltage at the coil (put black wire of dva on black wire and red on the other), should be around 110-150 volts if you see this you know you have adaquate primary voltage, put your timing light on the cylinder (running) if it flashes you have mutual induction...spark.

 

[Rapson]

Re: 1993 Yamaha 150 HP Alarm issue and runs rough.

I am asuming this is the same as mine (1987 140Hp). When the alarm goes off the computer puts the engine in a sort of safety mode, dropping the RMP to below 2000rmp amd makes the engine sound like crap.
How are you measuring the water temp? If it is by the tell tale, this water hasnt been through the head yet and will be cool. What about the temp of the head, after the alarm goes off try the 3 second test, that is can you put your hand on the head for 3 seconds with out burning your self.

I have had an overheating issue, check the thread here for a few other things to check. http://forums.iboats.com/showthread.php?t=456050

 

[bluewaterDevil]

Re: 1993 Yamaha 150 HP Alarm issue and runs rough.

Sorry Guys thanks for the help, I figured it out it was the poppet valve.

 

[Rapson]

Re: 1993 Yamaha 150 HP Alarm issue and runs rough.

Thats great that you sorted it out and was an easy fix, hope mine is the same thing!

 

[bluewaterDevil]

Re: 1993 Yamaha 150 HP Alarm issue and runs rough.

Bad news guys I still am having alarm and rev limiter issues. Could the problem be my pressure gauge on my dash?

 

[Rapson]

Re: 1993 Yamaha 150 HP Alarm issue and runs rough.

Have you had a look at my post? There is everything under the sun to check there which I have done and I am still getting over heating issues. Have you put your hand on the head when the alarm sounds to confirm that it is actually over heating and not a faulty alarm?