I hope someone here can help me with my frustration at figuring out what the problem is with my 1965 9.5 HP Evinrude motor. Here's the six points in a nutshell:
1)Two pulls to start and idles smoothly.
2)Once warm, performing low to full throttle (in drive gear) is instant.
3)High throttle will hold for about 20 seconds then motor will suddenly shut back to very low, as if to cut off for approximately 2 seconds.
4)While not touching throttle, motor will again return to full speed and hold for about 5-10 seconds. Then motor will suddenly shut back to very low, as if to cut off for approximately 2 seconds.
5)Then it will repeat problem over and over. Weird thing is you can run the motor at half speed (medium throttle forever and no problem. Its only when you increase to full throttle that problem happens).
6)Once motor is shut off for 10 to 15 minutes, it can require considerable amount of pulls to restart and hold idle.
So here's the story: I take it to two different marine mechanics to resolve the problem. After checking coil and points for spark, it is determined they're in excellent condition (the spark and plenty of it, even at high speed).
Both suspected the carburetor lower jet being plugged because when the demand for more fuel is not received, that's generally the case. So the first mechanic did a quick cleaning of the lower jet. This did not resolve the problem back out on the lake.
The next mechanic did a full cleaning (pulled the whole thing apart), said it was in good condition; float and all looked new. There was two tiny metal shavings found in the bowl. After cleaned and reassembled and ran at the marine service center, it seemed like it was running better ? so back out to the lake and of course the problem still occurred.
So back to the marine dealership. Then they suspected the hoses, that there might be a tiny, pinhole air leak in them. So the hoses were replaced. Back to the lake. Problem still exists.
So then it was surmised that maybe it was the external hose and primer bulb or tank. So we switched out the gas-line hose and changed fuel tanks. This also did not resolve the issue.
We then checked the screen on the fuel pump and it was clean.
Now, one weird thing I discovered and it could be big: if I held the choke out half-way, the motor would run at full throttle without hiccup.
It's frustrating to both myself and the mechanics because everything else is in good order. It's in excellent condition and very well-maintained. And we now know for sure that the carburetor is squeaky clean. Would anybody have any idea what could cause this problem?
Thanks sincerely,
Doug
1)Two pulls to start and idles smoothly.
2)Once warm, performing low to full throttle (in drive gear) is instant.
3)High throttle will hold for about 20 seconds then motor will suddenly shut back to very low, as if to cut off for approximately 2 seconds.
4)While not touching throttle, motor will again return to full speed and hold for about 5-10 seconds. Then motor will suddenly shut back to very low, as if to cut off for approximately 2 seconds.
5)Then it will repeat problem over and over. Weird thing is you can run the motor at half speed (medium throttle forever and no problem. Its only when you increase to full throttle that problem happens).
6)Once motor is shut off for 10 to 15 minutes, it can require considerable amount of pulls to restart and hold idle.
So here's the story: I take it to two different marine mechanics to resolve the problem. After checking coil and points for spark, it is determined they're in excellent condition (the spark and plenty of it, even at high speed).
Both suspected the carburetor lower jet being plugged because when the demand for more fuel is not received, that's generally the case. So the first mechanic did a quick cleaning of the lower jet. This did not resolve the problem back out on the lake.
The next mechanic did a full cleaning (pulled the whole thing apart), said it was in good condition; float and all looked new. There was two tiny metal shavings found in the bowl. After cleaned and reassembled and ran at the marine service center, it seemed like it was running better ? so back out to the lake and of course the problem still occurred.
So back to the marine dealership. Then they suspected the hoses, that there might be a tiny, pinhole air leak in them. So the hoses were replaced. Back to the lake. Problem still exists.
So then it was surmised that maybe it was the external hose and primer bulb or tank. So we switched out the gas-line hose and changed fuel tanks. This also did not resolve the issue.
We then checked the screen on the fuel pump and it was clean.
Now, one weird thing I discovered and it could be big: if I held the choke out half-way, the motor would run at full throttle without hiccup.
It's frustrating to both myself and the mechanics because everything else is in good order. It's in excellent condition and very well-maintained. And we now know for sure that the carburetor is squeaky clean. Would anybody have any idea what could cause this problem?
Thanks sincerely,
Doug
