MajBach
Chief Petty Officer
- Joined
- Jun 21, 2003
- Messages
- 564
Hi everyone. Some time ago I posted an issue with my engine not running right after doing a carb rebuild. I am revisiting that issue. Here are the details:
Motor is 1999 with about 700 hrs on it. It sat for 3 years and when I used it again, two of the carbs were leaking gas at idle...it was a mess. So, I changed all the gaskets, jets, plugs and tubes. It ran fine hooked up to a garden hose except it coughed occasionally at low rpms or if I 'gunned' it. When I took it out on the water, it started giving me problems.
The motor sounds like it is running fine, and smooth. If I advance the throttle up to about 85%, behavior is normal and boat accelerates, (although it seems to have less pep). If however at any point I push the throttle to 90% or above, you can hear what sounds like a cylinder drop (there is no coughing or sputtering so I don't think it's a fuel supply problem). If I back off the throttle, the cylinder fires again but if I leave it advanced the motor will slowly accelerate. At about 4300 rpm, the motor still sounds normal but it's running out of energy. It may reach 4500 or so and pull 32 knots (on a 16 1/2 foot aluminum). I used to top out at 5600 rpm at 42 knots.
Interestingly, I couldn't reproduce the symptoms with the boat on the trailer and backed into the water; I could only do it while moving. when I went WOT at the launch, the motor still ran on all 4 cylinders, although it didn't rev very high and just sounded like it was lugging. So basically, the motor doesn't seem to develop the power it used to and, under high throttle, it sounds like it is running on three cylinders.
Last time I was here the consensus was I installed a high speed jet wrong or something. I guess this is because the problem started after putting the carbs back on. But recently, when asking for advice on a good local Honda mechanic, several people suggested it was a coil problem. It seems like I won't be able to get it into a shop for awhile so thinking about trying to determine if it is a coil problem and how to test it.
Thanks
Motor is 1999 with about 700 hrs on it. It sat for 3 years and when I used it again, two of the carbs were leaking gas at idle...it was a mess. So, I changed all the gaskets, jets, plugs and tubes. It ran fine hooked up to a garden hose except it coughed occasionally at low rpms or if I 'gunned' it. When I took it out on the water, it started giving me problems.
The motor sounds like it is running fine, and smooth. If I advance the throttle up to about 85%, behavior is normal and boat accelerates, (although it seems to have less pep). If however at any point I push the throttle to 90% or above, you can hear what sounds like a cylinder drop (there is no coughing or sputtering so I don't think it's a fuel supply problem). If I back off the throttle, the cylinder fires again but if I leave it advanced the motor will slowly accelerate. At about 4300 rpm, the motor still sounds normal but it's running out of energy. It may reach 4500 or so and pull 32 knots (on a 16 1/2 foot aluminum). I used to top out at 5600 rpm at 42 knots.
Interestingly, I couldn't reproduce the symptoms with the boat on the trailer and backed into the water; I could only do it while moving. when I went WOT at the launch, the motor still ran on all 4 cylinders, although it didn't rev very high and just sounded like it was lugging. So basically, the motor doesn't seem to develop the power it used to and, under high throttle, it sounds like it is running on three cylinders.
Last time I was here the consensus was I installed a high speed jet wrong or something. I guess this is because the problem started after putting the carbs back on. But recently, when asking for advice on a good local Honda mechanic, several people suggested it was a coil problem. It seems like I won't be able to get it into a shop for awhile so thinking about trying to determine if it is a coil problem and how to test it.
Thanks
