94 Mercury 125 ELPTO on Baja 17' Islander

[bakerderek0]

I recently purchased a 1994 Baja 170 Islander. It has the 94 Mercury 125 ELPTO. (2 STROKE FOUR CYLINDER CARB). I changed all four spark plugs; changed fuel filter, and put a bottle of seafoam in with a 15 gal tank of gas. It has a 13x19 prop. Acceleration is sluggish, the engine will die if I give it too much throttle. At 5000rpms (WOT), Top Speed is 30mph. Any Ideas on what I need to do? I believe this boat was sitting for awhile before I purchased it. The compression test is 135 on the top two cylinders and 140 on the bottom two cylinders. Should I take the carbs off and clean them? I'm really at a loss here, any suggestions are welcome.

 

[bakerderek0]

Re: 94 Mercury 125 ELPTO on Baja 17' Islander

I just got back from a trip out today. I sat at the dock for an hour and did "Dunk's Seafoam Shock". I did two of the 15 minute treatments. It seemed to help alot on acceleration, it will accelerate smoothly.But no gains on top speed. Except now WOT is 4500rpms at 30mph. So I've called around and found a place that will do a full carb inspect & clean this week. So, I guess that's gonna be my answer.

 

[pigeon laker]

Re: 94 Mercury 125 ELPTO on Baja 17' Islander

Make sure your speedo and tach are accurate before spending any money.I don't know how to check the tach,but,use a GPS or mobile phone with a GPS app.to check your speed.I have a 17' bowrider with a 115 and run a 17" prop at about 5000rpms and 42mph.I am now trying to fix my motor because I used to get 5000rpm's and 50mph with a 19" prop.

 

[ClassyGlassy]

Re: 94 Mercury 125 ELPTO on Baja 17' Islander

Make sure your speedo and tach are accurate before spending any money.I don't know how to check the tach,but,use a GPS or mobile phone with a GPS app.to check your speed.I have a 17' bowrider with a 115 and run a 17" prop at about 5000rpms and 42mph.I am now trying to fix my motor because I used to get 5000rpm's and 50mph with a 19" prop.

You should be getting higher RPM and lower MPH by going down on pitch!

You both should read up on how pitch effects your RPM and top speed......

 

[bakerderek0]

Re: 94 Mercury 125 ELPTO on Baja 17' Islander

Make sure your speedo and tach are accurate before spending any money.I don't know how to check the tach,but,use a GPS or mobile phone with a GPS app.to check your speed.I have a 17' bowrider with a 115 and run a 17" prop at about 5000rpms and 42mph.I am now trying to fix my motor because I used to get 5000rpm's and 50mph with a 19" prop.

I did verify speed with a GPS unit. I haven't verified rpms yet, but I haven't seen a real reason too. I should have a high top speed with this prop, but I'm no where near 50mph. I really think it's in my carbs. We will find out soon. Thanks for the advice

 

[pigeon laker]

Re: 94 Mercury 125 ELPTO on Baja 17' Islander

I know that I should be getting higher rpm's and less speed(that seems OK,50 down to 42}.That's my problem,a reliable mechanic checked it out after I lost 400 rpm's with the 19"prop,told me nothing is wrong.Compression,spark and fuel delivery are all good.I switched to the 17" to prevent lugging the motor.I have rebuilt the carbs,fuel pump and put a new primer bulb on it,ran seafoam through it and still it doesn't perform the way it did when I first got it new.I am now replacing the exhaust divider plate gasket and hopefully that will solve the problem.