I've posted a couple of times in the forum about my lack of power issues and have tried everything I know to resolve this strange problem. Basically, the engine starts up immediately, idles great and runs pretty good up to about 1400 rpm. In neutral, if the throttle is advanced, I can't get over about 2,100 rpm. After that, additional throttle advance results in bogging and no additional rpm. No backfiring or other strange noises - just bogging. In gear, engine will throttle up to about 1400 rpm max - additional throttle advance makes no difference - just bogging, but never stalls. I've read everything in here on such subjects and my issue seems to defy logic. Here's what I have done to no avail:
1) New carburetor (no time on it yet except tests/adjustment at the dock)
2) New plug wires
3) New cap, rotor -- no avail. Pulled old distributor as I was concerned that I was not getting sufficient advance. Old distributor shaft had about an inch of play up and down. Didn't think that could be good and I thought I had found my smoking gun. Purchased rebuilt distributor and installed (electronic ignition). Timed engine. No change.
4) New wet exhaust (was concerned about backpressure issues and mine was original)
5) Pulled manifold and hot exhaust. No blockage. Carbon everywhere, but, hey, it's exhaust. Looked fine. Replaced exhaust manifold and flange with new gaskets.
6) Pulled plugs that were new approx. 10 hours (or less) of operating time ago. All fouled with lots of carbon evenly across all plugs (all looked just as dirty) - Not good so I replaced all plugs. No change in condition.
**Compression is 120-130 across all cylinders.
I'm at a loss. Any ideas out there. I'm tired of working on the engine and just want to go summer cruising. I'm about to pull the thing and have it completely rebuilt, but I know that's just out of frustration as with high compression values, easy starts and great idle like I have I can't see how the engine could need a rebuild. The engine has been very well maintained and looks showroom clean - no rust or annoying leaks.
I'm about to hire a mechanic to check things out cause I'm out of ideas. The only 2 additional thoughts I have are the following and I would appreciate any input on the likelihood of these causing my symptoms:
1) Possible elevated exhaust backpressure originating from the water lift muffler. Only problem with this idea is that there is great water flow out of the back of the boat - in neutral at about 1800 rpm water shoots about 10 feet behind the boat!
2) Valve clearances - could out of adjustment valve clearances cause these symptoms (fouling plugs and lack of power)? I know nothing about valve clearances or their symptoms. I have owned this engine for 1.5 years and never had issues until a few months ago. I just ignored the power loss symptoms as I usually just go sailing. It seems symptoms started shortly after a relatively long cruise (15+ hours of constant motoring each way), for whatever that's worth.
Thanks in advance for any advice! I'm glad to have new carb, distributor and wet exhaust (not to mention fresh water cooling) for peace of mind, but there are no more parts I can buy that I haven't already installed.
1) New carburetor (no time on it yet except tests/adjustment at the dock)
2) New plug wires
3) New cap, rotor -- no avail. Pulled old distributor as I was concerned that I was not getting sufficient advance. Old distributor shaft had about an inch of play up and down. Didn't think that could be good and I thought I had found my smoking gun. Purchased rebuilt distributor and installed (electronic ignition). Timed engine. No change.
4) New wet exhaust (was concerned about backpressure issues and mine was original)
5) Pulled manifold and hot exhaust. No blockage. Carbon everywhere, but, hey, it's exhaust. Looked fine. Replaced exhaust manifold and flange with new gaskets.
6) Pulled plugs that were new approx. 10 hours (or less) of operating time ago. All fouled with lots of carbon evenly across all plugs (all looked just as dirty) - Not good so I replaced all plugs. No change in condition.
**Compression is 120-130 across all cylinders.
I'm at a loss. Any ideas out there. I'm tired of working on the engine and just want to go summer cruising. I'm about to pull the thing and have it completely rebuilt, but I know that's just out of frustration as with high compression values, easy starts and great idle like I have I can't see how the engine could need a rebuild. The engine has been very well maintained and looks showroom clean - no rust or annoying leaks.
I'm about to hire a mechanic to check things out cause I'm out of ideas. The only 2 additional thoughts I have are the following and I would appreciate any input on the likelihood of these causing my symptoms:
1) Possible elevated exhaust backpressure originating from the water lift muffler. Only problem with this idea is that there is great water flow out of the back of the boat - in neutral at about 1800 rpm water shoots about 10 feet behind the boat!
2) Valve clearances - could out of adjustment valve clearances cause these symptoms (fouling plugs and lack of power)? I know nothing about valve clearances or their symptoms. I have owned this engine for 1.5 years and never had issues until a few months ago. I just ignored the power loss symptoms as I usually just go sailing. It seems symptoms started shortly after a relatively long cruise (15+ hours of constant motoring each way), for whatever that's worth.
Thanks in advance for any advice! I'm glad to have new carb, distributor and wet exhaust (not to mention fresh water cooling) for peace of mind, but there are no more parts I can buy that I haven't already installed.
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