I recently bought a older boat with a 1979 Evinrude 115 hp V4 2 stroke outboard motor. I love 2 stroke motors because they are easier to work on but sometimes are very moody. What I have checked so far..
Compression in all 4 cylinders are 123-125
Primer bulb holds pressure
Has 1/2 tank of fresh gas at 50:1
Out in the yard on muffs:
Starting process: Pump bulb, idle level max, choke 2-3 seconds. Engine fires then dies. Repeat process and engine cranks. Leave idle level max 5 seconds then engine idles but appears to idle high. Going from low idle to max idle rev is very slow and takes 5 seconds for the engine to catch up. You can manually turn the top carb and it revs fast.
1rst time to lake:
Had to repeat cranking process 5 times and let max idle for 10 seconds. Idle seemed high and starting was very slow and the engine RPMs had to catch up with the throttle. Then it wouldn't slow down and realized the throttle cable was not connected properly and just trolled the rest of the day.
Out in the yard 2nd trial:
Fixed the throttle cable and repeated cranking process. Still idle high. I turned the idle screw to reduce the idle and no change. Idle screw does not touch the block no more. Revs are slow to catch up with low to max idle.
Out to the lake #2:
I felt like a noob and over choked it. Engine flooded and can smell gas. Full idle or no idle, did not make a difference. It would not crank. I tilted the motor up where the exhaust was out of the water then it cranked fast. Idle still high and slow reaction time between low idle and high idle. Planned out good but slow. Ran around 42 mph (should run around 50-55 mph being a 115 on a 15.5' boat). Going down the lake I could hear it miss fire a little but at random. Stopped and fished for about a hour. Cranking was difficult again. Had to high idle for 10-15 seconds. When put it in gear would go dead. To make it take off you had to high idle then quickly put it in gear before idle dropped. After running at full throttle, I stopped at idle for 10 seconds and took off again with no problem. At one location I was using my fish finder for 15 mins at idle speed. Decided there was no fish and tried to plane out but it died. Had to high idle again for 5 min before it would go again. Behind the boat was white smoke and looked like a oil/fuel mixture in the water. Trailered the boat and went home.
At home again:
I pulled the plugs to look and see if they are clean. They was wet and black except where you gap them at. I noticed I have a exhaust leak out of the gasket on the back exhaust manifold which is leaking exhaust with blackish water. Rectifier is running good so there shouldn't be any stator issues. Considering all plugs look the same it shouldn't be a coil or power pack issue.
My thoughts:
Since the engine is running better trimmed or tilted up it may be the floats sticking overloading the engine with fuel? But maybe the linkage between the 2 carbs are not correct? I just purchased 2 carb rebuild kits, exhaust manifold gaskets, and water pump rebuild kit (which I typically always do when I buy a old motor but was lazy on this one).
Any ideas or think I'm on the correct path?
Compression in all 4 cylinders are 123-125
Primer bulb holds pressure
Has 1/2 tank of fresh gas at 50:1
Out in the yard on muffs:
Starting process: Pump bulb, idle level max, choke 2-3 seconds. Engine fires then dies. Repeat process and engine cranks. Leave idle level max 5 seconds then engine idles but appears to idle high. Going from low idle to max idle rev is very slow and takes 5 seconds for the engine to catch up. You can manually turn the top carb and it revs fast.
1rst time to lake:
Had to repeat cranking process 5 times and let max idle for 10 seconds. Idle seemed high and starting was very slow and the engine RPMs had to catch up with the throttle. Then it wouldn't slow down and realized the throttle cable was not connected properly and just trolled the rest of the day.
Out in the yard 2nd trial:
Fixed the throttle cable and repeated cranking process. Still idle high. I turned the idle screw to reduce the idle and no change. Idle screw does not touch the block no more. Revs are slow to catch up with low to max idle.
Out to the lake #2:
I felt like a noob and over choked it. Engine flooded and can smell gas. Full idle or no idle, did not make a difference. It would not crank. I tilted the motor up where the exhaust was out of the water then it cranked fast. Idle still high and slow reaction time between low idle and high idle. Planned out good but slow. Ran around 42 mph (should run around 50-55 mph being a 115 on a 15.5' boat). Going down the lake I could hear it miss fire a little but at random. Stopped and fished for about a hour. Cranking was difficult again. Had to high idle for 10-15 seconds. When put it in gear would go dead. To make it take off you had to high idle then quickly put it in gear before idle dropped. After running at full throttle, I stopped at idle for 10 seconds and took off again with no problem. At one location I was using my fish finder for 15 mins at idle speed. Decided there was no fish and tried to plane out but it died. Had to high idle again for 5 min before it would go again. Behind the boat was white smoke and looked like a oil/fuel mixture in the water. Trailered the boat and went home.
At home again:
I pulled the plugs to look and see if they are clean. They was wet and black except where you gap them at. I noticed I have a exhaust leak out of the gasket on the back exhaust manifold which is leaking exhaust with blackish water. Rectifier is running good so there shouldn't be any stator issues. Considering all plugs look the same it shouldn't be a coil or power pack issue.
My thoughts:
Since the engine is running better trimmed or tilted up it may be the floats sticking overloading the engine with fuel? But maybe the linkage between the 2 carbs are not correct? I just purchased 2 carb rebuild kits, exhaust manifold gaskets, and water pump rebuild kit (which I typically always do when I buy a old motor but was lazy on this one).
Any ideas or think I'm on the correct path?
