I have a 1988 Mercury 35HP motor that I am only getting 3100 rpm full throttle while under load on the water. I can put muffs on the motor and rev to 5000 rpm with the fast idle lever and with the throttle. This is my first boat and would appreciate any help I can get.
Here is a little info on the motor. My father-in-law bought this boat new in 1988 and only had it on the water maybe a dozen time and hadn't had it on the water since 2001, but has put muffs on it every now and then to run it at the house. I recently got the boat from him and after some fresh fuel it fired right up. I took it out to the lake and it ran fine other than the low rpm's. I have put in a larger fuel tank, new fuel line/bulb, spark plugs, plug wires, fuel line & filter and have rebuilt the carb. I have checked to make sure both plugs are getting fire and it seems like the coils output is fine. I have talked to a local shop and they just said they would have to start replacing parts to figure it out and I really don't want to just start replacing parts that may not be the cause. Any help would be very appreciated.