I was working on a friends direct injected, 2000 Yamaha 200 SX outboard (2-stroke) a few days ago, and he brought a question to my attention. Here it is as follows:
He's had it about a month, when he test drove it, he had 4 people in the boat and it ran like a dream. He got it, ran twice with 2 people in the boat and it ran like a dream. He took 4 people out and it wont get past about 3,800 RPM's. Took 2 people again and it ran like a dream. Just wont hit WOT with 4 people. He's changed nothing on the load, has'nt changed the prop or anything (19p Yamaha Stainless with 3 blades on the motor mounted to a 22' Key West CC).....just a issue that just kind of started.
I did a compession test hot with WOT: #1: 120psi #2: 125psi #3: 120psi #4:120psi #5: 125psi #6: 119psi
Changed the water fuel seperator filter, the old one was pretty clean
Did'nt find any leaks on the motor running or off
Fuel line stayed primed all day and night that I had the boat, starts at the slightest bump of the key, even cold
Changed the entire waterpump assembly
new gear oil
changed all 6 plugs
He hasnt ran it since he got the boat back, so I dont know if the problem is still there or not. Anyone have a idea of what may have caused this problem to start in the first place? And why would the (2) middle cylinders have higher compression than the (4) top and bottom cylinders?
He's had it about a month, when he test drove it, he had 4 people in the boat and it ran like a dream. He got it, ran twice with 2 people in the boat and it ran like a dream. He took 4 people out and it wont get past about 3,800 RPM's. Took 2 people again and it ran like a dream. Just wont hit WOT with 4 people. He's changed nothing on the load, has'nt changed the prop or anything (19p Yamaha Stainless with 3 blades on the motor mounted to a 22' Key West CC).....just a issue that just kind of started.
I did a compession test hot with WOT: #1: 120psi #2: 125psi #3: 120psi #4:120psi #5: 125psi #6: 119psi
Changed the water fuel seperator filter, the old one was pretty clean
Did'nt find any leaks on the motor running or off
Fuel line stayed primed all day and night that I had the boat, starts at the slightest bump of the key, even cold
Changed the entire waterpump assembly
new gear oil
changed all 6 plugs
He hasnt ran it since he got the boat back, so I dont know if the problem is still there or not. Anyone have a idea of what may have caused this problem to start in the first place? And why would the (2) middle cylinders have higher compression than the (4) top and bottom cylinders?