No matter what I do I can't get my 1981 Johnson 115HP (J115TLCIM) to run smooth consistently. It's usually great at the high RPM but hesitant at low. Feels like one cylinder might not be firing.
I do my I own work on the motor because I like mechanical stuff and can't really afford to hire a pro anyway (although with 20/20 hindsight I'd probably be ahead in the long run). I pay the price for my lack of knowledge though in that I usually will replace a part vs. troubleshooting it thoroughly. My rationale is that it's a very old motor with the original parts so I'm avoiding future problems. I've replaced every component in the ignition system all the way from the plugs to the stator (plugs, plug wires, coil assembly, power pack, rectifier, timer base, and stator). I've also gone through the carburetor.
That background brings me to my latest problem that I can't figure out. I finally bit the bullet and just replaced the stator (P/N 0581987) and timer base (P/N 0582014) with ones from CDI. The parts installation went smoothly but the timing and synchronization have me stumped. Here are the steps I've taken and the problems I've encountered.
1. Assured the timing pointer read TDC when #1 cylinder was at TDC
2. Assured that there is no play in the linkage between the cam follower and the throttle valves.
3. Assured that the cam follower aligns with the top mark on the cam at the initial point of contact.
This step was unclear to me:
4. The instructions I was following said to adjust the throttle cable adjustment wheel until the idle adjustment screw contacts the idle stop if it doesn't already touch. This seems to assume that the idle screw is positioned where it should be. It probably isn't because I tweaked it many times trying to get the engine to work better at idle so consider these messed up.
Here's where I'm really stuck:
5. The next step is to synchronize the throttle and timer linkage. You are supposed to attach a timing light to cylinder #1, start the engine, and slowly open the throttle with the control box warmup lever until the timing reads 4-6 degrees BTDC. Then, leaving the throttle in this position, you shut the engine off. Then you're supposed to adjust the throttle cam yoke as required to align with the top (short) mark on the throttle cam with the center of the cam roller.
My problem is that the timing light indicates the engine is idling about 20-25 degrees AFTER TDC (to the right of TDC on the flywheel)! I thought I might have a sheared key on the flywheel so I pulled it and the key is intact and in the slot.
I could really use your help on this ASAP. I'm taking the boat on vacation Jul 21-31. Unless I can get this fixed before Sunday it looks like the trolling motor will have to do all the work. I apologize in advance for any delays in responding to your questions after Sunday. The campsite is without cell phone access but we usually manage to escape for our daily "data fix" at some time each day. I'll be taking my tools!
Compression Readings:
#1: 95
#2: 100
#3: 90
#4: 97
Spark strong after stator replacement. Will jump 1/2" gap.
I do my I own work on the motor because I like mechanical stuff and can't really afford to hire a pro anyway (although with 20/20 hindsight I'd probably be ahead in the long run). I pay the price for my lack of knowledge though in that I usually will replace a part vs. troubleshooting it thoroughly. My rationale is that it's a very old motor with the original parts so I'm avoiding future problems. I've replaced every component in the ignition system all the way from the plugs to the stator (plugs, plug wires, coil assembly, power pack, rectifier, timer base, and stator). I've also gone through the carburetor.
That background brings me to my latest problem that I can't figure out. I finally bit the bullet and just replaced the stator (P/N 0581987) and timer base (P/N 0582014) with ones from CDI. The parts installation went smoothly but the timing and synchronization have me stumped. Here are the steps I've taken and the problems I've encountered.
1. Assured the timing pointer read TDC when #1 cylinder was at TDC
2. Assured that there is no play in the linkage between the cam follower and the throttle valves.
3. Assured that the cam follower aligns with the top mark on the cam at the initial point of contact.
This step was unclear to me:
4. The instructions I was following said to adjust the throttle cable adjustment wheel until the idle adjustment screw contacts the idle stop if it doesn't already touch. This seems to assume that the idle screw is positioned where it should be. It probably isn't because I tweaked it many times trying to get the engine to work better at idle so consider these messed up.
Here's where I'm really stuck:
5. The next step is to synchronize the throttle and timer linkage. You are supposed to attach a timing light to cylinder #1, start the engine, and slowly open the throttle with the control box warmup lever until the timing reads 4-6 degrees BTDC. Then, leaving the throttle in this position, you shut the engine off. Then you're supposed to adjust the throttle cam yoke as required to align with the top (short) mark on the throttle cam with the center of the cam roller.
My problem is that the timing light indicates the engine is idling about 20-25 degrees AFTER TDC (to the right of TDC on the flywheel)! I thought I might have a sheared key on the flywheel so I pulled it and the key is intact and in the slot.
I could really use your help on this ASAP. I'm taking the boat on vacation Jul 21-31. Unless I can get this fixed before Sunday it looks like the trolling motor will have to do all the work. I apologize in advance for any delays in responding to your questions after Sunday. The campsite is without cell phone access but we usually manage to escape for our daily "data fix" at some time each day. I'll be taking my tools!
Compression Readings:
#1: 95
#2: 100
#3: 90
#4: 97
Spark strong after stator replacement. Will jump 1/2" gap.
