clayhubler
New member
Hi all,
Been working on the boat for a long while, now I'm stuck.
Bought the boat 1.5 years ago. 1988 Smokercraft 22 OSI (same as sylvan offshore 22) with 3.0 Litre OMC Cobra. Tore the whole boat apart on the inside all the way to bare metal and rebuilt the decking and bulkheads, replaced all wiring and numerous engine components. New starter, electronic ignition, plugs, wires, coil. New intake/exhaust manifold, carburetor, fuel hoses, filters. Had the boat running great and was using it a lot this spring.
In May I got seawater in the fuel tank. So much that it overwhelmed the separator and killed the engine. I then pulled the fuel tank and cleaned and flushed the fuel lines and replaced fuel filter/ separator with one that has a drain on it. Ran the boat a while, seemed to be great. Checked for water in the separator and there hasn't been any. After I ran about 40 gallons of fuel through the engine, I noticed that it would hesitate when applying full throttle from idle, but otherwise ran good. That didn't last, however, because soon the engine started missing (I think its missing). At last it died altogether.
I was thinking the seawater had fouled the carb. I had a rebuild kit for the carb already, so I took it apart and there were parts inside that had rust forming on them, and the accelerator pump plunger was torn slightly (why???). Springs were rusted, and lots of crud in the bowl and such. I disassembled and cleaned the carb, reassembled everything and put it back in, headed to the lake. It idled poorly. However, it ran good under a load for about an hour and a half, and I was feeling pretty good, then it started missing again. Once it started, it escalated fast, and finally died only a couple minutes from the first indication of a problem.
I thought maybe I didn't clean it well enough, so I bought another kit and rebuilt it again, cleaning much more thoroughly. I did not find any water in the float bowl ( or the water separator), or any other problems when I disassembled it. I cleaned everything meticulously, made sure all the passages and orifices were clear. I reinstalled the carb and ran it on the muffs. Also put in new plugs, thinking maybe they were corroded from the salt. Idle was still rough, but it seemed ok at anything over 1000 rpm. I had a mechanic come look at it with me. We checked the spark, which was strong. I have quite a bit of pressure under the valve cover that I don't remember having before, but cannot be sure. I was concerned about this, but after feeling the flow, he said that the amount there didn't concern him at all. I am aware that this is a sign of blowby, but the engine compression checks out at 145 on all cylinders, and my oil level is correct, and it is not milky. I cannot find anything that is wrong with this engine. Neither could my mechanic friend. He suggested that I go to the lake and run it under load again, which I had not done since rebuilding the second time. So I did. I launched, let the engine warm up, and then headed to leave the no wake zone, but the engine started missing while only running about 1500 rpm and only about a hundred yards from the dock. I turned back.
This is the first times I've rebuilt a carb. I'm pretty good with mechanical stuff, but not real experienced with engines and such. But the carb just doesn't seem that complicated, and I was pretty sure that I had done a good job with the rebuild. But with nowhere else to turn and no more ideas, I decided to buy another carb from the place I got my original rebuilt carb. That carb worked great, and the boat was running great with it for months.
The new carb came today, and I put it on and ran the boat on the muffs. It idled poorly, and ran ok at higher rpms. It is behaving exactly the same. I didn't take it to the lake, I already know what is going to happen. Now what I mean when I say idled poorly- not exactly a rough idle. Even at 700-800 rpm, which is higher that the 650 I should be able to get, the engine with run real smooth for a short amount of time, then with no change to the mixture screws or throttle, it will start shaking and missing. This has been a recurring symptom, and I'm sure that if I go to the lake it will miss before I get away from the dock. It runs okay at higher rpms when not under load, but in gear in the water, it starts at about 1500.
I forgot to mention that I did run the boat on a separate fuel tank with fresh gas in it. I ran long enough to make sure that the boat was running on the new gas (not that the gas was old at all, but I have suspected bad gas). This trial achieved the same results, so I am pretty confident that the fuel system is good. I did this after I rebuilt the carb for the second time, before installing the new carb. I'm just trying to eliminate options here.
My boat does not have a pcv valve, it has a plastic elbow with a hose that goes to the spark arrestor, none of which is plugged. Some people have suggested a vacuum leak, but aside from this hose leading to the arrestor, I don't know of any other components in the vacuume system.
If anybody has any suggestions or advice, it would be greatly appreciated. The summer is almost over, and this boat is killing me.
Thanks
Been working on the boat for a long while, now I'm stuck.
Bought the boat 1.5 years ago. 1988 Smokercraft 22 OSI (same as sylvan offshore 22) with 3.0 Litre OMC Cobra. Tore the whole boat apart on the inside all the way to bare metal and rebuilt the decking and bulkheads, replaced all wiring and numerous engine components. New starter, electronic ignition, plugs, wires, coil. New intake/exhaust manifold, carburetor, fuel hoses, filters. Had the boat running great and was using it a lot this spring.
In May I got seawater in the fuel tank. So much that it overwhelmed the separator and killed the engine. I then pulled the fuel tank and cleaned and flushed the fuel lines and replaced fuel filter/ separator with one that has a drain on it. Ran the boat a while, seemed to be great. Checked for water in the separator and there hasn't been any. After I ran about 40 gallons of fuel through the engine, I noticed that it would hesitate when applying full throttle from idle, but otherwise ran good. That didn't last, however, because soon the engine started missing (I think its missing). At last it died altogether.
I was thinking the seawater had fouled the carb. I had a rebuild kit for the carb already, so I took it apart and there were parts inside that had rust forming on them, and the accelerator pump plunger was torn slightly (why???). Springs were rusted, and lots of crud in the bowl and such. I disassembled and cleaned the carb, reassembled everything and put it back in, headed to the lake. It idled poorly. However, it ran good under a load for about an hour and a half, and I was feeling pretty good, then it started missing again. Once it started, it escalated fast, and finally died only a couple minutes from the first indication of a problem.
I thought maybe I didn't clean it well enough, so I bought another kit and rebuilt it again, cleaning much more thoroughly. I did not find any water in the float bowl ( or the water separator), or any other problems when I disassembled it. I cleaned everything meticulously, made sure all the passages and orifices were clear. I reinstalled the carb and ran it on the muffs. Also put in new plugs, thinking maybe they were corroded from the salt. Idle was still rough, but it seemed ok at anything over 1000 rpm. I had a mechanic come look at it with me. We checked the spark, which was strong. I have quite a bit of pressure under the valve cover that I don't remember having before, but cannot be sure. I was concerned about this, but after feeling the flow, he said that the amount there didn't concern him at all. I am aware that this is a sign of blowby, but the engine compression checks out at 145 on all cylinders, and my oil level is correct, and it is not milky. I cannot find anything that is wrong with this engine. Neither could my mechanic friend. He suggested that I go to the lake and run it under load again, which I had not done since rebuilding the second time. So I did. I launched, let the engine warm up, and then headed to leave the no wake zone, but the engine started missing while only running about 1500 rpm and only about a hundred yards from the dock. I turned back.
This is the first times I've rebuilt a carb. I'm pretty good with mechanical stuff, but not real experienced with engines and such. But the carb just doesn't seem that complicated, and I was pretty sure that I had done a good job with the rebuild. But with nowhere else to turn and no more ideas, I decided to buy another carb from the place I got my original rebuilt carb. That carb worked great, and the boat was running great with it for months.
The new carb came today, and I put it on and ran the boat on the muffs. It idled poorly, and ran ok at higher rpms. It is behaving exactly the same. I didn't take it to the lake, I already know what is going to happen. Now what I mean when I say idled poorly- not exactly a rough idle. Even at 700-800 rpm, which is higher that the 650 I should be able to get, the engine with run real smooth for a short amount of time, then with no change to the mixture screws or throttle, it will start shaking and missing. This has been a recurring symptom, and I'm sure that if I go to the lake it will miss before I get away from the dock. It runs okay at higher rpms when not under load, but in gear in the water, it starts at about 1500.
I forgot to mention that I did run the boat on a separate fuel tank with fresh gas in it. I ran long enough to make sure that the boat was running on the new gas (not that the gas was old at all, but I have suspected bad gas). This trial achieved the same results, so I am pretty confident that the fuel system is good. I did this after I rebuilt the carb for the second time, before installing the new carb. I'm just trying to eliminate options here.
My boat does not have a pcv valve, it has a plastic elbow with a hose that goes to the spark arrestor, none of which is plugged. Some people have suggested a vacuum leak, but aside from this hose leading to the arrestor, I don't know of any other components in the vacuume system.
If anybody has any suggestions or advice, it would be greatly appreciated. The summer is almost over, and this boat is killing me.
Thanks
