crackedglass
Petty Officer 2nd Class
- Joined
- Jan 4, 2009
- Messages
- 199
I have a strange issue with a 1989 Evinrude 110hp, (E110MLCEM), it runs fine, starts easy and has 145-145-146-147 compression. The motor appears to have very little use and looks nearly new. The problem I'm having is that while underway the RPM creeps up, I at first thought it was the controls but what I found is that the engine gains RPM with running time.
It's not running hot, (new w/p and t-stat), and its not missing. I even tried disconnecting the enrichment solenoid with no change.
What happens is that I start out say 3/4 throttle at about 3800 rpm on a steady cruise, then I begain gaining speed and RPM, if I keep going, I end up with the throttle pulled nearly completely back to neutral running at over 4,000 RPM. If I stop, turn off the motor and restart, all if fine and I can continue for a few miles before it starts again.
I've gone so far as to run with the cover off and to watch the throttle linkage, and it don't move, yet the engine gains RPM. When I stop, put the boat in neutral the motor will no idle down, unless I kill the ignition and restart, and like magic, it's all better. The timing plate and linkage is good, all of the linkage is fine, (I even replaced the control box and cables thinking that they were part of the problem at first). When it acts up it still runs fine and will accelerate just fine to full throttle, but the idle keeps climbing. I had figured it had to be linkage or maybe a vacuum leak but it can be reset to normal buy simple stopping and restarting the engine.
One shop told me that maybe there's a crankcase leak causing this, maybe a bad seal or a crack somewhere but again, turning the engine off and right back on ends the problem for often several miles or so.
When it's acting up, I can close the throttle plates and the engine is still racing at nearly 4,000 rpm. kill the switch, let the engine stop, then restart and it's fine. It seems to be getting worse with cold weather, but I'm not sure how much that has to do with it. It never fails to start, never is hard to start, fuel usage hasn't changed, oil usage is normal as well, (VRO is still installed although a new VRO pump was installed at the time of overhaul several years ago as a precaution).
I'm open to suggestions here, so far this thing has me stumped.
It's not running hot, (new w/p and t-stat), and its not missing. I even tried disconnecting the enrichment solenoid with no change.
What happens is that I start out say 3/4 throttle at about 3800 rpm on a steady cruise, then I begain gaining speed and RPM, if I keep going, I end up with the throttle pulled nearly completely back to neutral running at over 4,000 RPM. If I stop, turn off the motor and restart, all if fine and I can continue for a few miles before it starts again.
I've gone so far as to run with the cover off and to watch the throttle linkage, and it don't move, yet the engine gains RPM. When I stop, put the boat in neutral the motor will no idle down, unless I kill the ignition and restart, and like magic, it's all better. The timing plate and linkage is good, all of the linkage is fine, (I even replaced the control box and cables thinking that they were part of the problem at first). When it acts up it still runs fine and will accelerate just fine to full throttle, but the idle keeps climbing. I had figured it had to be linkage or maybe a vacuum leak but it can be reset to normal buy simple stopping and restarting the engine.
One shop told me that maybe there's a crankcase leak causing this, maybe a bad seal or a crack somewhere but again, turning the engine off and right back on ends the problem for often several miles or so.
When it's acting up, I can close the throttle plates and the engine is still racing at nearly 4,000 rpm. kill the switch, let the engine stop, then restart and it's fine. It seems to be getting worse with cold weather, but I'm not sure how much that has to do with it. It never fails to start, never is hard to start, fuel usage hasn't changed, oil usage is normal as well, (VRO is still installed although a new VRO pump was installed at the time of overhaul several years ago as a precaution).
I'm open to suggestions here, so far this thing has me stumped.
