Hi All,
My Islander 34 with Atomic 4 is exhibiting a power loss problem similar to that seen by many others who are posting on the forum. However, the problem I am observing has a different wrinkle. We have been sailing the boat regularly about once a week for the last 18 months (we sail in the Southern California Channel Island area) . The engine ran perfectly (until 2 months ago) such that while motoring in the harbor under still conditions we could achieve a speed of 6.3 knots @ 1700 RPM (this speed was only maintained for a few seconds for testing purposes as we have a 5 knot speed limit in the harbor). At present the best we can do is 1500-1600 RPM with speed of about 4.6 knots. The 1500 RPM is reached with about 1/3 throttle and any increase in throttle beyond 1/3 does not produce any results, just a slight suffocating sound at the air intake. At an idle the RPM is not limited---engine revs to 3000 RPM very quickly. We probably have 3-4 hours on the motor with this power loss situation and recently developed the unusual wrinkle I mention earlier in this post------after motoring in from a sail the engine quit abruptly. In the instant state of panic I tried to restart the engine. Engine would not restart so I took about 2 minutes of deep breaths and tried again--engine fired up and we motored into the slip. Yesterday we were entering the harbor from a sail (had been motoring for about 5 minutes) when the engine quit---this time I immediately choked the engine and it fired up instantly. This allowed us to drop sail and motor in which took about 15 minutes with no engine problems other than the steady state power loss issue.
Here are items of interest in chronological order---NOTE: power loss started about 2 months ago:
1. The PO installed a rebuilt Zenith carb (new design) about 2 years ago. Engine running fine until 2 months ago.
2. Seven months ago I replaced the fuel tank sender unit.
3. Six months ago I replaced the water pump with MMI unit.
4. 2+ months ago I replaced the water separating fuel filter cartridge (Sierra unit) and the fuel line from the tank to the filter housing.
5. In the last two weeks I replaced the entire leaky exhaust system because I suspected that high back pressure may have been responsible for power loss---it looks like back pressure was not an issue. At the same time I also replaced the thermostat housing and we now run at a consistent 140 degrees. Also checked compression: #1=100psi, #2=85psi, #3=82psi, #4=100psi.
6. Checked the low oil pressure switch and noticed that it has been bypassed by PO so that it is not causing the engine to quit abruptly.
Note that I replaced the water separating fuel filter before the power loss issue was noticed (I think). I cannot be sure that we did not have the power loss before the filter was replaced nor can I be sure that the engine did not run OK for a few outings after the filter was replaced. The problem with my observations is that we usually only need about 1200-1400 RPM to get in and out of the harbor. The power loss was first noticed when bucking a head wind where we wanted to make some way in order to get back to the dock in a timely fashion.
The engine quitting whenever it feels like it is my greatest concern since it creates considerable unrest.
At this point I am not sure where to begin an analysis---maybe with the fuel filter? And how would I check the fuel filter issue?
Any and all suggestions on how to approach this problem would be greatly appreciated.
Thanks,
Bruce
My Islander 34 with Atomic 4 is exhibiting a power loss problem similar to that seen by many others who are posting on the forum. However, the problem I am observing has a different wrinkle. We have been sailing the boat regularly about once a week for the last 18 months (we sail in the Southern California Channel Island area) . The engine ran perfectly (until 2 months ago) such that while motoring in the harbor under still conditions we could achieve a speed of 6.3 knots @ 1700 RPM (this speed was only maintained for a few seconds for testing purposes as we have a 5 knot speed limit in the harbor). At present the best we can do is 1500-1600 RPM with speed of about 4.6 knots. The 1500 RPM is reached with about 1/3 throttle and any increase in throttle beyond 1/3 does not produce any results, just a slight suffocating sound at the air intake. At an idle the RPM is not limited---engine revs to 3000 RPM very quickly. We probably have 3-4 hours on the motor with this power loss situation and recently developed the unusual wrinkle I mention earlier in this post------after motoring in from a sail the engine quit abruptly. In the instant state of panic I tried to restart the engine. Engine would not restart so I took about 2 minutes of deep breaths and tried again--engine fired up and we motored into the slip. Yesterday we were entering the harbor from a sail (had been motoring for about 5 minutes) when the engine quit---this time I immediately choked the engine and it fired up instantly. This allowed us to drop sail and motor in which took about 15 minutes with no engine problems other than the steady state power loss issue.
Here are items of interest in chronological order---NOTE: power loss started about 2 months ago:
1. The PO installed a rebuilt Zenith carb (new design) about 2 years ago. Engine running fine until 2 months ago.
2. Seven months ago I replaced the fuel tank sender unit.
3. Six months ago I replaced the water pump with MMI unit.
4. 2+ months ago I replaced the water separating fuel filter cartridge (Sierra unit) and the fuel line from the tank to the filter housing.
5. In the last two weeks I replaced the entire leaky exhaust system because I suspected that high back pressure may have been responsible for power loss---it looks like back pressure was not an issue. At the same time I also replaced the thermostat housing and we now run at a consistent 140 degrees. Also checked compression: #1=100psi, #2=85psi, #3=82psi, #4=100psi.
6. Checked the low oil pressure switch and noticed that it has been bypassed by PO so that it is not causing the engine to quit abruptly.
Note that I replaced the water separating fuel filter before the power loss issue was noticed (I think). I cannot be sure that we did not have the power loss before the filter was replaced nor can I be sure that the engine did not run OK for a few outings after the filter was replaced. The problem with my observations is that we usually only need about 1200-1400 RPM to get in and out of the harbor. The power loss was first noticed when bucking a head wind where we wanted to make some way in order to get back to the dock in a timely fashion.
The engine quitting whenever it feels like it is my greatest concern since it creates considerable unrest.
At this point I am not sure where to begin an analysis---maybe with the fuel filter? And how would I check the fuel filter issue?
Any and all suggestions on how to approach this problem would be greatly appreciated.
Thanks,
Bruce
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