New motor test

[HTHM]

Well, I put the 20 hp on Lure Laundry, and on GPS I am doing 20 MPH at wide open throttle. Not too bad I think! However............when I try to go 1/2 throttle the motor will not run very smoothly, and when I try to troll it stalls out all the time. Any ideas as to why this is?

This was done with me on the tiller, and my 175 pound son in the front. The rate of speed was the same when positions were reversed. The motor is a 81 (?) Johnson seahorse.

[modny]

that seems slow to me , even at WOT

 

my old merc 20 could push me, my dad and my 17 foot sylvan at close to 30 mph

 

has the motor had a carb clean? or adjustment? might have to do with the floats. could be running rich and chokin out maybe.

[HTHM]

It was just bought from Bay city marine, and they indicated that the motor was fully serviced and tuned up. My boat is a 14' fiberglass.

[nancur373]

have the carb and jets cleaned. If problem still persists try taking a compression reading.

[modny]

bay city on hester is a pretty solid place/

 

i'd call them up and see what they say...especially if u just bought it

[HTHM]

bay city on hester is a pretty solid place/

 

i'd call them up and see what they say...especially if u just bought it

I agree, it took me a year before I finally pulled the trigger on a deal there, and Clarence seems like a decent fellow. I asked him prior to the purchase if the motor had been serviced, listened to it run, and felt confident walking out the door.

I will talk to him on Monday.

[Greencoachdog]

Pull the spark plugs and see what they look like.

 

What gas/oil mix ratio were you using? Was it fresh?

 

How old is you fuel line?

[BillM]

If you just bought it, take it back. Make the dealer worry about it.

[nancur373]

Also the choke may be sticking a little.

[glen]

20mph top speed is about right for that (boat 400lbs or so) plus people.

 

I aint sure what is wrong with it. But if the fuel line is old and the rubber is hard i would buy a new one.

[forrest]

Obvious issues with a new purchase? Call the dealer.

 

20MPH.....nothing wrong with 20MPH as long as 20MPH is normal for that boat, engine, prop set up. Ask the dealer about that too.

 

forrest

[blehst]

my dad has a 14.5 foot boat. with a 30 and he only does 32mph. so id say your right around ball park

Edited July 6, 2008 by blehst

[Zamboni]

that seems slow to me , even at WOT

 

my old merc 20 could push me, my dad and my 17 foot sylvan at close to 30 mph

 

His reading was by gps-guessing your reading was the boats dreemometer?

[modny]

His reading was by gps-guessing your reading was the boats dreemometer?

 

 

i'm not even lying about this at all.

 

mind you it was like 16 years ago when i weighed 150 lbs less, and my old man atleast 50

 

hahah

[sturgman]

Just a thought... I am experiencing the same problems as you with my 9.9 after installing a new propeller.. Maybe your prop pitch is incorrect as I have discovered mine is..

[FinS]

that seems slow to me , even at WOT

 

my old merc 20 could push me, my dad and my 17 foot sylvan at close to 30 mph

 

has the motor had a carb clean? or adjustment? might have to do with the floats. could be running rich and chokin out maybe.

 

 

id like to see that on video

[HTHM]

Pull the spark plugs and see what they look like.

 

What gas/oil mix ratio were you using? Was it fresh?

 

How old is you fuel line?

Plugs are brand new, (dealer has indicated that the motor was just tuned up, with new points and condenser and he says the coil is good)

Gas is 50 - 1 approximately 2 months old with stabilizer in it.

My fuel line is max one year old, looks brand new.

[HTHM]

Just a thought... I am experiencing the same problems as you with my 9.9 after installing a new propeller.. Maybe your prop pitch is incorrect as I have discovered mine is..

original prop as I understand it

[Fish4Eyes]

My 40hp evinrude does not like to troll either, but when on the throttle it goes smooth.

[Randy]

....... when I try to troll it stalls out all the time.......

 

I agree with other posters, this would lead me to believe that the carburetor would need cleaning. Since you just bought it, take it back to the dealer and get him to fix it.

[Zamboni]

i'm not even lying about this at all.

 

mind you it was like 16 years ago when i weighed 150 lbs less, and my old man atleast 50

 

hahah

 

Didn't mean to offend-boats speedometers were generally innacurate and most people are suprised at their actual speed when a gps is used. Those GPS units must be very heavy as they cause many boats to go 5-10mph slower

[HTHM]

Well, I just looked over the motor, and yes the plugs are new, the fuel lines appear to be sound, however I am missing the lean rich adjustment knob at the center of the motor. Could it be that the motor is running too rich or too lean??

[forrest]

Well, I just looked over the motor, and yes the plugs are new, the fuel lines appear to be sound, however I am missing the lean rich adjustment knob at the center of the motor. Could it be that the motor is running too rich or too lean??

 

Anything is possible, fuel systems are tricky.....a service manual is your motors second best friend.

 

There is almost nothing worse than a man made problem, if its free, before anything gets messed up worse ask the dealer.

 

forrest

[modny]

Didn't mean to offend-boats speedometers were generally innacurate and most people are suprised at their actual speed when a gps is used. Those GPS units must be very heavy as they cause many boats to go 5-10mph slower

 

 

well im just going by another boats speedo so it def could have been inaccurate

[bigbuck]

I'd give them a call and let them know that they owe you a lean adjustment knob, you may be running either too rich or too lean and that's why she doesn't like trolling or part throttle.