I have a 1993 40HP Evinrude. The motor starts up easy, other than needing to press the primer every few seconds when its a cold start for 15 seconds or it will die again. It seems to run good at WOT and moderate RPMs, with a smooth feel and sound.
However, I do notice a few things that through all my work, have not gone away. First, when running at a slow idle, the motor will kick every few seconds (3-10) more than just normal vibration. Running on muffs out of water, you can "see" the kick jolt the motor. It also sounds like there could be a slight miss during idle, and I suspect that might be related to the kick. But overall, idle sounds smooth. The miss becomes more apparent sometimes during a slow rev-up from idle. For example, I've had this happen a few times on the water where I'm running at high speed, slow down for a few seconds then slowly pickup speed to a moderate level. There might be a miss, almost like a harmonic response it sounds like "pop pop pop pop" where it sounds normal in-between the pops. To get rid of it, I slow back down to idle and speed up again. Usually a second time fixes it. The rough idle at the lowest idle can kill the motor while under load.
Here is the maintenance I've done in the past year that hasn't fixed the issue.
Carbs removed and cleaned, jets cleaned, new gaskets.
New fuel hoses from the carbs to the pump.
New plugs.
Disconnected all electrical connections made on the terminal block near the CDI.
When I cleaned the electrical connections near the cdi, I noticed one of the yellow wire connections on the terminal bar had the screw stripping out the plastic. Basically, whoever last assembled it torqued that screw too much and it augured out some plastic. It isn't as strong of connection as it should be. I used a light coating of dielectric grease to help prevent further corrosion.
I also did a link and sync per my Clymers book after cleaning the carbs. Long story short, it ran horrible after following the procedure. The carbs are in sync, but basically the timing on the boat is advanced significantly in my opinion to obtain a decent idle.
I've run the motor with one plug at a time disconnected to see if I could tell which cylinder was missing, but the motor seemed to run ok with either cylinder disconnected.
Does any one else have any ideas as to what may be the cause of these issues, and are they related?
I was thinking the electrical system may be suspect. Is there a way to test the power pack and stator? Maybe the timing advance to obtain a good idle is causing the miss at higher RPMs? I have a tinytach as well that monitors one of the plug wires, it too seems to jump around (500-750) like there is a miss during idle, but it isn't designed for that, its just a digital tach.
TIA.
However, I do notice a few things that through all my work, have not gone away. First, when running at a slow idle, the motor will kick every few seconds (3-10) more than just normal vibration. Running on muffs out of water, you can "see" the kick jolt the motor. It also sounds like there could be a slight miss during idle, and I suspect that might be related to the kick. But overall, idle sounds smooth. The miss becomes more apparent sometimes during a slow rev-up from idle. For example, I've had this happen a few times on the water where I'm running at high speed, slow down for a few seconds then slowly pickup speed to a moderate level. There might be a miss, almost like a harmonic response it sounds like "pop pop pop pop" where it sounds normal in-between the pops. To get rid of it, I slow back down to idle and speed up again. Usually a second time fixes it. The rough idle at the lowest idle can kill the motor while under load.
Here is the maintenance I've done in the past year that hasn't fixed the issue.
Carbs removed and cleaned, jets cleaned, new gaskets.
New fuel hoses from the carbs to the pump.
New plugs.
Disconnected all electrical connections made on the terminal block near the CDI.
When I cleaned the electrical connections near the cdi, I noticed one of the yellow wire connections on the terminal bar had the screw stripping out the plastic. Basically, whoever last assembled it torqued that screw too much and it augured out some plastic. It isn't as strong of connection as it should be. I used a light coating of dielectric grease to help prevent further corrosion.
I also did a link and sync per my Clymers book after cleaning the carbs. Long story short, it ran horrible after following the procedure. The carbs are in sync, but basically the timing on the boat is advanced significantly in my opinion to obtain a decent idle.
I've run the motor with one plug at a time disconnected to see if I could tell which cylinder was missing, but the motor seemed to run ok with either cylinder disconnected.
Does any one else have any ideas as to what may be the cause of these issues, and are they related?
I was thinking the electrical system may be suspect. Is there a way to test the power pack and stator? Maybe the timing advance to obtain a good idle is causing the miss at higher RPMs? I have a tinytach as well that monitors one of the plug wires, it too seems to jump around (500-750) like there is a miss during idle, but it isn't designed for that, its just a digital tach.
TIA.
