eavega
Lieutenant
- Joined
- Apr 29, 2008
- Messages
- 1,377
Hello folks
So I FINALLY went out on a FISHING trip on my boat yesterday. No tests to run on the motor, no trying out a new prop or trim setting. Just fishing. Didn't catch a thing, but I still had a great time with my two buddies.
The motor ran very nicely for the most part. total of 20 miles by my GPS, including a full 10 min WOT run from the last fishing spot to the ramp, and I still seem to have about 2.5 gallons of fuel in my 6-gallon tank.
Now for the problem; the motor ran great at idle, and at a slow half-throttle at about 3K RPM. At full throttle, a couple of times it seemed that just for a moment it wanted to throttle down on its own. I heard it, but my two fishing buddies didn't even notice. The Tach didn't even register a significant change in RPMs, but I definitely heard the engine wind down for a second. The problem occurred at WOT as we were crossing some choppy-ish water (might have been another boat's wake). I'm looking for some root cause for this and wanted to get some ideas. My first suspicion is there is air getting into my fuel line somewhere, which caused a momentary fuel starvation and thus a hiccup in the engine speed. I am led to this diagnosis as I think through the entire trip, and remember that after our first or second start, the engine didn't start with a quick key bump, as it had first thing in the morning, and for the rest of the trip. When I had the problem starting it up, I ran through a cold start procedure, and THEN is started up. Part of the cold start is to prime the motor to fill the carbs, so in RETROSPECT I am thinking that the motor had lost its prime somewhere, which again would indicate air getting into the system either from the priming bulb or perhaps from the fuel pump. The fuel line and priming bulb are brand new. When I got the motor, I did not replace the fuel lines, but I did note that they had been replaced in the recent past with ethanol-resistant lines. I didn't notice any evidence of a fuel leak, but if there is a very small leak under the cowling somewhere, I may not see it as the fuel may evaporate before I get a chance to inspect.
Other things I can think of is that there is a loose wire or component somewhere that momentarily grounded out going over rough water, but I don't know if that would explain the hard starting incident. I'm not even sure that the hard starting incident was related to the momentary loss of power, but I since it is the only issue the motor is exhibiting, I am working on the assumption that they are related.
Any other thoughts? Any suggestions as to what would be a good test to try and prove or disprove my theory? Any help or suggestions would be greatly appreciated.
Rgds
So I FINALLY went out on a FISHING trip on my boat yesterday. No tests to run on the motor, no trying out a new prop or trim setting. Just fishing. Didn't catch a thing, but I still had a great time with my two buddies.
The motor ran very nicely for the most part. total of 20 miles by my GPS, including a full 10 min WOT run from the last fishing spot to the ramp, and I still seem to have about 2.5 gallons of fuel in my 6-gallon tank.
Now for the problem; the motor ran great at idle, and at a slow half-throttle at about 3K RPM. At full throttle, a couple of times it seemed that just for a moment it wanted to throttle down on its own. I heard it, but my two fishing buddies didn't even notice. The Tach didn't even register a significant change in RPMs, but I definitely heard the engine wind down for a second. The problem occurred at WOT as we were crossing some choppy-ish water (might have been another boat's wake). I'm looking for some root cause for this and wanted to get some ideas. My first suspicion is there is air getting into my fuel line somewhere, which caused a momentary fuel starvation and thus a hiccup in the engine speed. I am led to this diagnosis as I think through the entire trip, and remember that after our first or second start, the engine didn't start with a quick key bump, as it had first thing in the morning, and for the rest of the trip. When I had the problem starting it up, I ran through a cold start procedure, and THEN is started up. Part of the cold start is to prime the motor to fill the carbs, so in RETROSPECT I am thinking that the motor had lost its prime somewhere, which again would indicate air getting into the system either from the priming bulb or perhaps from the fuel pump. The fuel line and priming bulb are brand new. When I got the motor, I did not replace the fuel lines, but I did note that they had been replaced in the recent past with ethanol-resistant lines. I didn't notice any evidence of a fuel leak, but if there is a very small leak under the cowling somewhere, I may not see it as the fuel may evaporate before I get a chance to inspect.
Other things I can think of is that there is a loose wire or component somewhere that momentarily grounded out going over rough water, but I don't know if that would explain the hard starting incident. I'm not even sure that the hard starting incident was related to the momentary loss of power, but I since it is the only issue the motor is exhibiting, I am working on the assumption that they are related.
Any other thoughts? Any suggestions as to what would be a good test to try and prove or disprove my theory? Any help or suggestions would be greatly appreciated.
Rgds