Ran great for half hour, than lost power.

[flakeys2005]

I have had this boat for 12 days. I took her out on the lake three times, on the ocean twice and today on the river.

I took the boat out on the river today and she ran great for about 30 min. and then she started to sputter for a few seconds. I throttled up a bit and she smoothed out, but the longer I ran the more frequently she started to sputter until I just didn't have any power over 1500 rpm. That was fine for a good portion of the trip because it is loaded with no wake zones, but this problem seems to be getting worse each time I take the boat out. At the start of our trip, we get out of the no wake zone and throttle up and right away we are at 25 to 30mph at 3000 rpm. On the way back though (and we turned around because the sputtering was turning into loss of power) we got out of the NWZ and I throttled her up and there was no power at all, just a feeling of the motor straining, or maybe starving for fuel? I don't know. So we cruise back to the launch at a comfortable 6 to 8 mph and wait for the ramp to clear. In that 5 to 10 minutes, she was back to normal. I gave her some gas and she was off.
What could be causing this apparent fuel starvation? I didn't overheat at all. If my gauges are accurate, then I was at about 120 to 130 degrees.

I did notice last week that my choke was loose from the carb. and there seemed to be a vacuum leak but after asking on this forum, I was able to tighten that back up, so I don't think that is the problem. I'm guessing carb clean, adjust, rebuild or replace.

Thanks for looking. Mike.

 

[84Monaco]

Re: Ran great for half hour, than lost power.

I've been having a similar problem that I'm pretty sure is electrical in nature. What kind of engine, ignition system, carb etc.?

 

[flakeys2005]

Re: Ran great for half hour, than lost power.

I've been having a similar problem that I'm pretty sure is electrical in nature. What kind of engine, ignition system, carb etc.?

It is a 1988 OMC3.0 4 cyl. with a points ignition and I think a 2 barrel carb with heat activated choke. The previous owner had it tuned at the end of last season. I don't know how thoroughly, but it has new plugs, wires and cap. I think it also has new rotor.

The first two times I took her out we ran on the lake for two hours with no problems at all. The third time was the first time I noticed the sputtering, so I just brought her in because I thought maybe my fuel gauge was faulty and we were about to run out. That was not the case. The first time on the ocean she was flawless (maybe a bit small for the waters but flawless). The second time on the ocean she was great for the first 16 or 17 miles, (about an hour) but on our way back to the dock she started to do what she did today. Today we got about 8 miles before she started to act up.

 

[myoldboat2]

Re: Ran great for half hour, than lost power.

I would check for water in the fuel tank and also change both fuel filters (at fuel pump and at carb).

I always use high octane gas, and avoid ethanol if I can.

It's possible to get a tank of bad fuel. There have been times when I've siphoned it all out and refilled to be sure. I fed the siphoned gas to my truck about 5 gal each truck fillup.

You could check the voltage at the coil when you start out and when it starts sputtering.

Check the choke plate angle when it starts sputtering. It could be a choke problem because the throttle adds more fuel, and if the choke is closing you don't get enough air, the mixture is too rich and it sputters out. I would try removing the choke cover and coil when it starts sputtering.

 

[flakeys2005]

Re: Ran great for half hour, than lost power.

i changed the fuel filter in the fuel pump and installed afuel water separator. I just idled for about 3o min. and seems fine. I am going to take her out on the lake in the next couple of days and see how she goes.

Thanks for your replies, Mike.