MarineEngine.com does not offer troubleshooting assistance or repair advice by email or by telephone.
You are invited to join our public Boat Repair Forum to seek assistance from other members.
You may also visit the Boat Motor Manuals section of our site to obtain a service manual.
It should idle down nicely.----Perhaps throttle plate is opening too early.----What other trouble shooting / inspection have you done.-----It is not always a " carburetor " issue.[/QUOTE
The throttle plate doesn't start to open until the roller gets slightly past the two notches on the throttle cam....so at idle, the roller is probably 3/4" to the right of the two notches....(if you are facing the motor from carburetor side) So it's retarded good...all my fuel lines are zip tied. The motor was converted from a 20 to a 25 hp via carb, intake manifold, throttle cam, and timing adjustment, but even as a 20 hp, it idled the same. Once i get the idle down to 1000 rpm, it gradually idles down on it's own over 30 seconds or so, but it gets rougher, and bucks more, and once it hits like 880 or so, it cuts out entirely....Not sure what more to do....Could it be an ignition issue?
Does spark fire across a gap of 3/8" or more , yes or no ?----Have you checked the flywheel key, yes or no ?----What are the compression reading on this motor ?
I was having issues like this last year on my 1985 20hp.I would hit the same rpms and it would want to stall.I had multiple issues, some due to old age of motor.I had a lead plug on top of carb come out/loose for slow speed circuit and was sucking air.Also, I found the fuel pump to block gasket(all appeared original and screws were tight) was sucking air and it was running lean and the pistons showed it.Think I also found air being sucked in from one of the small fuel lines(zip tied) going to carb or manfold or manual fuel primer, I can't remember which it was now.After I got things sealed up properly and the lead plug fixed and a good carb. clean also it ran and idled like new and I could drop the idle way down and put a tach on it for fun.Needle is set at 1.5 turns out, base plate is fully retarded, if i go much beyond a quarter turn in or out on the needle, it kills it. My question is, will it hurt the motor to idle at this rpm range??....It runs awesome other than that, and it'll troll down to 2.7 mph(good enough for me) Just wondering if there is something im missing, or an adjustment/carb cleaning needs to be done??
I was having issues like this last year on my 1985 20hp.I would hit the same rpms and it would want to stall.I had multiple issues, some due to old age of motor.I had a lead plug on top of carb come out/loose for slow speed circuit and was sucking air.Also, I found the fuel pump to block gasket(all appeared original and screws were tight) was sucking air and it was running lean and the pistons showed it.Think I also found air being sucked in from one of the small fuel lines(zip tied) going to carb or manfold or manual fuel primer, I can't remember which it was now.After I got things sealed up properly and the lead plug fixed and a good carb. clean also it ran and idled like new and I could drop the idle way down and put a tach on it for fun.
