Here's my tale of woe:
My engine was running fine until about three weeks ago when upon starting it, it barely ran. I had to have the throttle half way open to get it to continue to run. If I lowered the throttle, the engine would surge and die. Even with the throttle open, the engine would surge up and down.
I found out (by removing spark plug wires) that it was only running on the two rear cylinders. Removing the wires from the front two had no effect. When I removed wires from one of the two rear cylinders, the engine would die. By holding the spark plug wires close to the spark plugs, I could see that the two effected cylinders were getting spark, although the spark for #1 looked rather weak and erratic.
As I had not changed fuel filters before (I have had the boat for a year and I don't know when, or if, the previous owner had ever changed them); I changed both the Sierra water seperator filter and the inline fiter between the Sierra and the fuel pump. This had no effect, other than to make the boat not start at all. After priming the fuel pump, I was able to get the motor to start, but it coninued to run on only two cylinders.
Since the two effected cylinders are next to each other, I performed a compression test to see if I had a problem with the head gasket or with the valves. Compression was fine - about 120 on each cylinder.
I then proceeded to remove and clean the distributor cap and rotor. Again, no effect. After removing, cleaning and replacing the carburator twice, the engine ran fine!!
I went back to the boat the following day and again two days thereafter. Each time, the boat started right up and ran fine. I thought that I was home free!!
Last Saturday, my wife and I went to the boat to do some interior renovation tasks. After finishing, I dcided to run the engine for a while. It ran like crap again with the same problem!!
I then ordered MMI's carburator service kit. I went to the boat today and changed out all of the jets, gaskets, etc. according to Don's instructions and sprayed carburator cleaner into all of the passages. I also removed and cleaned the sediment bowl. Again, no effect. The engine ran like crap.
Next, I went to West Marine and bought new spark plug wires, distributor cap and rotor. I had replaced the spark plugs a few months ago so this time I removed the front two and cleaned them. They were wet, I suppose from not having fired.
After trying for seven hours to get the beast to cooperate, I finally gave up and came home to write this plea for help.
I would replace the coil next, but I've always heard that coils either work or they don't. And I can't imagine the coil working for two cylinders and not for the others.
Please help me, I'm out of ideas.
Thanks,
Charles Taylor
My engine was running fine until about three weeks ago when upon starting it, it barely ran. I had to have the throttle half way open to get it to continue to run. If I lowered the throttle, the engine would surge and die. Even with the throttle open, the engine would surge up and down.
I found out (by removing spark plug wires) that it was only running on the two rear cylinders. Removing the wires from the front two had no effect. When I removed wires from one of the two rear cylinders, the engine would die. By holding the spark plug wires close to the spark plugs, I could see that the two effected cylinders were getting spark, although the spark for #1 looked rather weak and erratic.
As I had not changed fuel filters before (I have had the boat for a year and I don't know when, or if, the previous owner had ever changed them); I changed both the Sierra water seperator filter and the inline fiter between the Sierra and the fuel pump. This had no effect, other than to make the boat not start at all. After priming the fuel pump, I was able to get the motor to start, but it coninued to run on only two cylinders.
Since the two effected cylinders are next to each other, I performed a compression test to see if I had a problem with the head gasket or with the valves. Compression was fine - about 120 on each cylinder.
I then proceeded to remove and clean the distributor cap and rotor. Again, no effect. After removing, cleaning and replacing the carburator twice, the engine ran fine!!
I went back to the boat the following day and again two days thereafter. Each time, the boat started right up and ran fine. I thought that I was home free!!
Last Saturday, my wife and I went to the boat to do some interior renovation tasks. After finishing, I dcided to run the engine for a while. It ran like crap again with the same problem!!
I then ordered MMI's carburator service kit. I went to the boat today and changed out all of the jets, gaskets, etc. according to Don's instructions and sprayed carburator cleaner into all of the passages. I also removed and cleaned the sediment bowl. Again, no effect. The engine ran like crap.
Next, I went to West Marine and bought new spark plug wires, distributor cap and rotor. I had replaced the spark plugs a few months ago so this time I removed the front two and cleaned them. They were wet, I suppose from not having fired.
After trying for seven hours to get the beast to cooperate, I finally gave up and came home to write this plea for help.
I would replace the coil next, but I've always heard that coils either work or they don't. And I can't imagine the coil working for two cylinders and not for the others.
Please help me, I'm out of ideas.
Thanks,
Charles Taylor
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