2006 YAM 90hp 4 Stroke surging

[bilj]

Engine surges while throttle is up. About every second the RPMS jump back and forth.
Example - while Runnin 4k RPMs, engine dropped to 1.5k RPMs for 1 second then wen back to 4k. Lowerd RPMs to 3k, same thing.

Worked fine through all ranges, all day.
Idles fine.

 

[justintime]

Re: 2006 YAM 90 4 Stroke surging

sounds like fuel pump

 

[bilj]

Re: 2006 YAM 90 4 Stroke surging

sounds like fuel pump

Any method for trouble shooting that?

 

[justintime]

Re: 2006 YAM 90 4 Stroke surging

pump primer bulb up when running it and see if she picks up rpm's

 

[bilj]

Re: 2006 YAM 90 4 Stroke surging

pump primer bulb up when running it and see if she picks up rpm's

Thanks for the troubleshooting tip.
I tried it and nothing happened - bulb was tight already.

I am thinking that the problem is electrical in nature. The RPMs move quickly and lead me to beleive it is not a fuel problem.

Got any more suggestions or troubleshooting tips?

 

[justintime]

Re: 2006 YAM 90 4 Stroke surging

test spark and look at plugs

 

[bilj]

Re: 2006 YAM 90 4 Stroke surging

test spark and look at plugs

Are any of you aware of any aftermarket plug wire manufacturers that make plug wires that are not $35 a piece for this motor?

 

[justintime]

Re: 2006 YAM 90 4 Stroke surging

nope, you need to buy the coil!