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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 1988 omc cobra engine in my boat. Its a 5.7 GM with

Customer Question

I have a 1988 omc cobra engine in my boat. Its a 5.7 GM with breaker and points ignition. The boat started to lose power a few summers ago but hasn't been bad enough to keep us off the lake. As of last fall, its got no power under load(5mph top speed)lugging under all throttle ranges and coughing black smoke and plugs are carbon fowled bad. I bought a rebuilt carb from national carb and then sent it back to be rechecked after it didn't help.(they ran it on a live engine and said Its fine) After that I installed a new coil, points, condenser, esa switches, cap and rotor as well as plug wires. Didn't figure it was a compression thing but I checked all cylinders anyway and they seem fine at 140-145 psi. when I was trying to retime the engine after replacing distributer parts I struggled because the number 1 wire wasn't light up the timing light consistently. I put the timing light on all the other wires and they lit the light up properly. I took the wire off of number two and put it on number one and the problem was still there which tells me its not the plug wire. got any solid ideas what im dealing with.
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.
Hello. My name is Tan. What kind of voltage do you have at the ignition coil key on?Have you tried swapping the spark plug with another spark plug? Do you use ethanol enriched fuel? Have you tried running the boat on a different fuel source?