billythegrape
Seaman Apprentice
- Joined
- Jun 5, 2021
- Messages
- 35
Hi, here from Knoxville, TN.
I am at a loss and need help. I have a 24' pontoon boat. I had a 50hp johnson on there that worked perfectly. However, it was a short shaft and kept coming out of the water, so I decided to see if someone would trade for a long shaft. I got the 78 as an equal trade; tested compression and it was good so I took it home and put it on.
The engine ran like a top. It felt like it was twice as fast and we got to the island we go to in Norris Lake in record time. On the way back it started acting up, lost tons of power and was generally running like crap. I had noticed that the stator and rectifier showed signs of melting, so when I got home I ordered them.
Put the new stator and rectifier on and then set timing (WOT, all plugs out, spark tester and timing light lead on cyl 1) to 15 deg as this was 2 deg less than 17. Decided to rebuild the carbs and change all the fuel lines and pump; got that done, carbs were very clean, but had old gaskets. Tried it on the muffs, it was hard to start but got going and was ok, so I brought it to the lake. It ran badly with no power and died at the ramp. Pulled the plugs, found water on them.
Pulled the head, it was very corroded, but the cylinders looked good and the head and water jacket were straight. Replaced the head gasket, water jacket gasket, melted pressure relief valves and grommets, and the thermostat and associated gaskets. Cleaned everything. Boat ran ok on the muffs, so I brought it down to the lake and it died on the ramp. Got it going and pulled plug wires; #3 cyl was not contributing so I figured the coil was dead. It was melted.
Replaced all the coils and decided to do the exhaust manifold gaskets as well because I read that those should be changed at some point; since the head was so nasty I figured it must be to. It was. Cleaned everything on it, replaced all gaskets. Took it to the lake today. It fired right up, but had no power. Drove it for a bit, pulled the cover off the carbs, saw that the chokes were all shut. Adjusted the chokes to their proper positions, it ran better with more power but still not fabulously.
I am at a loss. What else can I check? The plug wires? I messed with them while going around on the boat and they shocked the crap out of me; they don't seem like they fit super well into the coils. The engine feels like it is being held back by something. Compression is still fine at 120-120-115. HELP!!
I am at a loss and need help. I have a 24' pontoon boat. I had a 50hp johnson on there that worked perfectly. However, it was a short shaft and kept coming out of the water, so I decided to see if someone would trade for a long shaft. I got the 78 as an equal trade; tested compression and it was good so I took it home and put it on.
The engine ran like a top. It felt like it was twice as fast and we got to the island we go to in Norris Lake in record time. On the way back it started acting up, lost tons of power and was generally running like crap. I had noticed that the stator and rectifier showed signs of melting, so when I got home I ordered them.
Put the new stator and rectifier on and then set timing (WOT, all plugs out, spark tester and timing light lead on cyl 1) to 15 deg as this was 2 deg less than 17. Decided to rebuild the carbs and change all the fuel lines and pump; got that done, carbs were very clean, but had old gaskets. Tried it on the muffs, it was hard to start but got going and was ok, so I brought it to the lake. It ran badly with no power and died at the ramp. Pulled the plugs, found water on them.
Pulled the head, it was very corroded, but the cylinders looked good and the head and water jacket were straight. Replaced the head gasket, water jacket gasket, melted pressure relief valves and grommets, and the thermostat and associated gaskets. Cleaned everything. Boat ran ok on the muffs, so I brought it down to the lake and it died on the ramp. Got it going and pulled plug wires; #3 cyl was not contributing so I figured the coil was dead. It was melted.
Replaced all the coils and decided to do the exhaust manifold gaskets as well because I read that those should be changed at some point; since the head was so nasty I figured it must be to. It was. Cleaned everything on it, replaced all gaskets. Took it to the lake today. It fired right up, but had no power. Drove it for a bit, pulled the cover off the carbs, saw that the chokes were all shut. Adjusted the chokes to their proper positions, it ran better with more power but still not fabulously.
I am at a loss. What else can I check? The plug wires? I messed with them while going around on the boat and they shocked the crap out of me; they don't seem like they fit super well into the coils. The engine feels like it is being held back by something. Compression is still fine at 120-120-115. HELP!!
