Hi I am new to the forums and have a problem with my johnson gt150 that doesn't make since to me. And I am by no means a mechanic. I have had 2 props on this motor. First was a 14 1/2 24p raker (on a 17ft 1989 nitro 1800tf) . When I throttled down it sounded like it reved high but tach gauge showed a very slow increase in rpms as the boat took stood up high and planed out at about 8 seconds. After planed and tilted it would run to a max of around 4400 rpm and 53 GPS mph. The motor is properly tilted and trimmed. So after these findings I desire to try a different propeller.
I put a viper 14 3/4 19p on and it came out of the hole within 3 seconds and ran strong. Wot is 5200 rpm at 43 GPS mph. This doesn't make since to me. Even with the first prop this motor should scream on a 17ft bass boat. It drags a little at idle but other than that it sounds good like it's running strong. I've checked compression and all cylinders are within 5% of 80. I have new champion ql77jc4 plugs in. I've cleaned carbs, and fuel line replaced and bulb appears to work correctly.
Could it be something like one of the coils not firing? Or something else?
I put a viper 14 3/4 19p on and it came out of the hole within 3 seconds and ran strong. Wot is 5200 rpm at 43 GPS mph. This doesn't make since to me. Even with the first prop this motor should scream on a 17ft bass boat. It drags a little at idle but other than that it sounds good like it's running strong. I've checked compression and all cylinders are within 5% of 80. I have new champion ql77jc4 plugs in. I've cleaned carbs, and fuel line replaced and bulb appears to work correctly.
Could it be something like one of the coils not firing? Or something else?