bergsofafeather
Cadet
- Joined
- Aug 2, 2003
- Messages
- 27
Good afternoon to all. This is my first visit (and post) to this site, and please pardon my ignorance of motors in advance. Also, I will be ordering a manual today! I own a 1975 Mercury 85hp, s/n: 4722152. Two years ago, I had a local boat shop do a spring tune up: spark=good, compression=125 all cylinders, replaced water pump, fuel fitting, fuel lines, rebuilt carbs and fuel pump, ran engine tuner thru motor to clean out carbon, to the tune of $1100. The first day out it started and idled great, but when I tried to accelerate it would die....to make a long, horrible day short 
, we eventually got back to shore and the boat shop adjusted a jet to properly function under load. Today, the nightmare began again, it started great, with full choke, but as I eased the choke back, it would die, if I pushed it back up it would rev again, or if I pushed the little button next to the choke handle. I also tried to leave the choke all the way up and put the motor in gear, but it would die immediately. I will assume (probably incorrectly) that the "low speed idle jet is set too lean" (I just read about this in someone's post earlier today). I removed the front covers from the motor and am apparently looking at the intake manifold, six 1" dia. "cones" with two carbs behind the manifold, one at the top and one at the bottom behind the manifold plate. Each carb looks to have two screws accessible from this point: the one on the left is brass, says .072 on it and has a hole through it, it is tightened down. The one on the right is steel, no hole, and appears to be 1-1/2 turns out. Can anyone tell me if one of this sounds like the same problem, and if so, am I in the right place for adjusting jets, and finally, which one and how much? Again, I am terribly sorry for my lack of knowledge, and will have a manual soon, but I want to go salmon fishing today!! Also, I am running 87 octane, 50:1 with Johnson Evinrude XD25 Formula, and have just put in fresh plugs.
, we eventually got back to shore and the boat shop adjusted a jet to properly function under load. Today, the nightmare began again, it started great, with full choke, but as I eased the choke back, it would die, if I pushed it back up it would rev again, or if I pushed the little button next to the choke handle. I also tried to leave the choke all the way up and put the motor in gear, but it would die immediately. I will assume (probably incorrectly) that the "low speed idle jet is set too lean" (I just read about this in someone's post earlier today). I removed the front covers from the motor and am apparently looking at the intake manifold, six 1" dia. "cones" with two carbs behind the manifold, one at the top and one at the bottom behind the manifold plate. Each carb looks to have two screws accessible from this point: the one on the left is brass, says .072 on it and has a hole through it, it is tightened down. The one on the right is steel, no hole, and appears to be 1-1/2 turns out. Can anyone tell me if one of this sounds like the same problem, and if so, am I in the right place for adjusting jets, and finally, which one and how much? Again, I am terribly sorry for my lack of knowledge, and will have a manual soon, but I want to go salmon fishing today!! Also, I am running 87 octane, 50:1 with Johnson Evinrude XD25 Formula, and have just put in fresh plugs.