Logo
FULL SITE MENU

Throttle issues related to spark plugs?

N

Newboatowner123

New member
Recently bought a 1996 Larson fish and ski 17' with a 3.0 l Volvo penta in it. Previous owner said it ran great ( of course), but he did seem pretty honest. Had it out on a local dam, starts like a dream and sounds really smooth no misses. But could only get up to 20 mph and roughly 2500 rmp. Pulled it out so we could take it out when we had more time, through it out on the lake, same issues but this time it would only go to 1500 rmp and sub 10 mph. Took the cover off in the water and throttled up by hand while not engaged, couldn't get it over 3500 rmp, thought throttle cable issue was at play so took the handle off checked cable and adjusted the tension screw slightly, took it out 2 more times ran nice, 4000 rpm , 33 ish mph, thought that was the issue, wrong! Must have been a fluke, had it out sunday and couldn't get it over 2500 rmp. Manually move throttle, still 2500. Took it to marine repair, he says spark plug gap issue and wrong plugs, and that when he had it out prior to replacing plugs was at 3500 rpm but definitely had more. Could this be the issue? Why would it get worse from the previous owner to us?

Never owned a boat before
 
I am not sure how to start a post or if i can but i have a similar problem with plugs,,, working on a inline 6 cyl mercury 2 stroke, first time i have encountered this and hope someone has experienced this before. When number 2 or 5 are removed while the engine is running it appears to increase in rpm's. I am thinking that there is an internal problem with the engine. Any comments greatly appreciated. thanks
 
Last edited:
If it starts and idles like a dream I doubt it's spark plugs. Does it have electronic ignition?

dakotaoutboard; there is a mercury outboard forum board if you go to the main forum page. This is for 4 cycle sterndrives. You might have better luck over there.
 
Back
Top