Re: 1992 johnson 120hp idling problem
Ok,put boat in water today ,and may I remind that this engine was removed from another boat and has had this problem since I installed it on my boat, my boat originally uses a 20 inch shaft engine,this one is a 25 inch on a jack plate,meaning that the possibility of it being set to low or to high out of the water, may be effecting back pressure, manifesting in low idle problems,with that being said. Here are the results, first of all the RPM and TIMING with engine at idle and newtral was 1200 RPM 8 degree ATDC, with engine at idle in foward gear was 900 to 950 RPM 8 degree ATDC, after this I proceeded to perform the step by step IDLE TIMMING adjustment,went through it several times to make sure I got it right, onece done proceeded to adjust timing for increase or decrease of idle rpm,the book recomends to stay between 8 degrees decreasing no more than 4 degrees ATDC to reaise idle, and to increas it no more than 10 to 12 degrees ATDC to lwer idle, I took it to 12 degrees ATDC and the results were as follows, idle in newtral 990 to 1010 RPM, idle in foward gear 850 to 900 RPM, Idle could not be lowered to less than 850 RPM in any case, the recommended rpm in gear is 575 to 700 RPM. Ater this I removed the air box and did the tooth pick test,really dint make any difference in idle, then with air box still removed I noticed that problem developed just when butterflies start to open on carbs, and if you keep going a little more it levels out. I must say though that the idle adjustment improved the situation about a good 70 %, at this point it is at least alot more better to deal with, but it really is not perfect yet, I really nam not sure if I have a lean or a ritch mixure problem,I did chech the cold start selanoid and made sure it dint leak into combustion chamber, one thing I have not done is adjust the engine height, I noyiced that out of water with muffs on rpm's are higher,maybe lowering engine down a little will encrease the back pressure and eliminate the lean sneeze, I will try to do this adjustment tommorrow when I get out of church, will let you know how it works out. thanks to all again
Ok,put boat in water today ,and may I remind that this engine was removed from another boat and has had this problem since I installed it on my boat, my boat originally uses a 20 inch shaft engine,this one is a 25 inch on a jack plate,meaning that the possibility of it being set to low or to high out of the water, may be effecting back pressure, manifesting in low idle problems,with that being said. Here are the results, first of all the RPM and TIMING with engine at idle and newtral was 1200 RPM 8 degree ATDC, with engine at idle in foward gear was 900 to 950 RPM 8 degree ATDC, after this I proceeded to perform the step by step IDLE TIMMING adjustment,went through it several times to make sure I got it right, onece done proceeded to adjust timing for increase or decrease of idle rpm,the book recomends to stay between 8 degrees decreasing no more than 4 degrees ATDC to reaise idle, and to increas it no more than 10 to 12 degrees ATDC to lwer idle, I took it to 12 degrees ATDC and the results were as follows, idle in newtral 990 to 1010 RPM, idle in foward gear 850 to 900 RPM, Idle could not be lowered to less than 850 RPM in any case, the recommended rpm in gear is 575 to 700 RPM. Ater this I removed the air box and did the tooth pick test,really dint make any difference in idle, then with air box still removed I noticed that problem developed just when butterflies start to open on carbs, and if you keep going a little more it levels out. I must say though that the idle adjustment improved the situation about a good 70 %, at this point it is at least alot more better to deal with, but it really is not perfect yet, I really nam not sure if I have a lean or a ritch mixure problem,I did chech the cold start selanoid and made sure it dint leak into combustion chamber, one thing I have not done is adjust the engine height, I noyiced that out of water with muffs on rpm's are higher,maybe lowering engine down a little will encrease the back pressure and eliminate the lean sneeze, I will try to do this adjustment tommorrow when I get out of church, will let you know how it works out. thanks to all again