maineiac5586
Master Chief Petty Officer
- Joined
- Feb 14, 2009
- Messages
- 817
Hi. I sold a 1989 yamaha 40 hp 3 cylinder tiller oil injected manual start to a friend. He took it out and it falls on its face when trying to accelerate. Compression is strong at 130 psi in all 3 cylinders. Spark is good on all 3.
I had him squeeze the primer ball when it happens and he said he thinks it improves slightly. The motor ran fine on my engine stand but I am aware under load is a different story. I had him try a different fuel tank along with a new hose assembly (regular black fuel hose) no different. I am a little confused when i look at the carb diagram on boats. Net it shows a electric choke primer on the bottom carb. This motor doesn't have that style enrichment . It has square top carbs as depicted in the diagram but no electronic enrichment. Not sure why that is. I will be picking up his boat and bringing it to my house to look into the issue. I guess ill start with carb cleaning in my Ultrasonic machine. Anyone have any inputs? He said its a bearing to start, manual start and has to pull a bunch of times. Once warm it starts on 1 pull. This motor has the feature that when it starts up cold or hot it runs at a high idle for a bit then kicks down on its own. He said when it kicks down it doesn't stall so maybe the low speed parts of the carbs are ok.? Here's a video of what it does. It wants to accelerate but then goes kind of flat even with throttle twisted ti full. Thank you for reading my long post.
I had him squeeze the primer ball when it happens and he said he thinks it improves slightly. The motor ran fine on my engine stand but I am aware under load is a different story. I had him try a different fuel tank along with a new hose assembly (regular black fuel hose) no different. I am a little confused when i look at the carb diagram on boats. Net it shows a electric choke primer on the bottom carb. This motor doesn't have that style enrichment . It has square top carbs as depicted in the diagram but no electronic enrichment. Not sure why that is. I will be picking up his boat and bringing it to my house to look into the issue. I guess ill start with carb cleaning in my Ultrasonic machine. Anyone have any inputs? He said its a bearing to start, manual start and has to pull a bunch of times. Once warm it starts on 1 pull. This motor has the feature that when it starts up cold or hot it runs at a high idle for a bit then kicks down on its own. He said when it kicks down it doesn't stall so maybe the low speed parts of the carbs are ok.? Here's a video of what it does. It wants to accelerate but then goes kind of flat even with throttle twisted ti full. Thank you for reading my long post.
