89' 100 GT Johnson - Power/Torque Loss

[tommy.noble]

Hello,
I have a 1989 Stratos 266 Fish and Ski. It has an 89' 100 GT Johnson. I purchased this boat in March and have had it out about a dozen times. The motor has ran great since I have purchased it. However, over the last couple of trips I have noticed a small decrease in overall power. At first it was nothing too noticeable. At first I could run at max capacity (4 poeple) and plane out with no problems. Gradually With max load it was having trouble getting it to plane and need someone to hop up front to get the nose down. Once it planes it runs fine. Last week I put in some sea foam as well as changed the plugs in attemps to get its power back. once I got to the lake I noticed that it idled smoother and the shifting into drive was also smoother. Once I passed the no wake zone I punched it.....the initial thrust seemed good...But I could not get it to plane. Once again I needed someone to jump up front to get it to plane. Once we were planed it seem to me that I had more top end speed prior to changing the plugs even thought it didnt have the initial torque to get me out of the water assistance free. At one point in the day it was only my friend in the boat and me on a tube behind....The boat would not plane with one person in the boat!!!! As the day continued to progress, the boat began dieing while it was idling. after dieing it would not fire up as easily as it always does. Can anyone please tell me where to start trouble shooting? Also, I am not very mechanically inclined so please explain to me as if I were 5 (lol) what needs to be done. Thank you!!!

P.S. For the first couple of month I used quicksilver oil as instructed by the person who sold it to me...After talking to my father he told me the oil has little contribution to the performance so I changed to a genaric oil and have now used just under one gallon of this genaric oil. This is the only other change I have made to the boat since it was purchased.

 

[tashasdaddy]

Re: 89' 100 GT Johnson - Power/Torque Loss

start with compression and a spark check with a tester. also be sure your boat is not holding any unwanted water in the foam, under the deck.

another item could be.
Ethanol and fuel lines
replace all fuel line with Alcohol resistant lines. Ethanol deteriorates, the rubber lines, then they start to sluff off on the inside, going directly to the carbs. Settling to the bottom of the bowl. Contaminating the carbs high speed jets. clean a rebuild carbs, flushing fuel line before connecting to carbs.

 

[tommy.noble]

Re: 89' 100 GT Johnson - Power/Torque Loss

I ended up disconnecting my fuel line from the gas tank and sticking the fuel line into a bottle of sea foam. pumped the fuel ball to draw in straight seam foam and just ran it on that for about 5 minutes...smoked like crazy but seemed to do the trick the next day....gave me my power back and had no problem planeing....you mentioned unwanted water in the foam under the deck...how can I look to see if there is water in the foam? If there is water...how do i get rid of it? Thank you.

Also, does the type of oil I use make a significant difference in overall performance?