3.0GS lack of performance after adding thermostat???

[wayni208]

I just recently bought a 1995 Crestliner Sportfish which has the 3.0GS sterndrive. It had been garaged for a few years. I rebuilt the carb and drained the old fuel.

Last night I took it out to the lake to do a shakedown cruise to see where I was at. I was fairly pleased although I noticed a few things to work on.

I dialed in the carburetor fuel mixture and idle and was happy enough with 800rpms in gear in the water. Other than that: I noticed the temp gauge wasn't reading at all. The previous owner had removed the thermostat to deal with overheating issues. I installed a thermostat and now the gauge registers. I had no heat issues while testing.

I did have a substantial lack of performance. Yesterday it was pretty snappy - I was able to cruise it at around 3600-3800 rpms on plane. Today, I can not get past 3000 or plane the boat at all.

Other than the thermostat and fuel mixtures (which I did reset to factory specs as it was last night - no change) the only thing I did differently was to fill it with more gas. I did almost fill the tank. Originally I had ethanol free, 87 octane - probably 5 gallons left. I added 15 gallons ethanol blend, 89 octane.

Then to top it all off I lost the battery. Complete - no power to starter or gauges. Thankful that it had an electric troller to get me back with. I'm more comfortable chasing down the electrical I think. We'll see.

Anyway - any ideas where to start first regarding my engine power issues?

Thanks.
Wayne

 

[RCSConstruction]

Bad alternator or battery? If the alternator was not charging/putting out power, you were getting weak spark, among other things.

 

[Scott Danforth]

my guess is that the crud that was in the tank and dried out from sitting has now been re-hydrated with the new gas and you are getting crud in the carb.

check the inlet filter to the carb. you may want to invest in a fuel/water separator filter. the 3.0 generally doesnt come with them.

 

[wayni208]

The alternator is working fine. There was a three battery hookup - a cranker and a couple deep cycles for the troller. The cranker is shot so I'll be replacing it. I took them out of parallel and hooked up one of the deep cycles to test it and the alternator and have no issues.

I have just replaced the rotor and cap and put new plugs all around. The wires were all good.

I found the issue with the battery dying out on me though. The 50amp breaker was popped. It didn't occur to me that these were thermistor types and it would have to get nice and cool to reset when I was on the lake. After an hour or so out of the water though it came back around. Not sure why it would have popped though.

 

[wayni208]

I'll take a look at the inlet valve and make sure it isn't fouled up. When I did the rebuild there was not an inlet filter installed. My kit came with one but did not have the spring intended to go in as well. I opted to not install it figuring if nothing else I would get an inline filter to keep external to the carb. I keep wishing I had done it anyway as something has to be better than nothing. Thanks for the tip on the fuel/water separator. It looks like a good thing to get regardless.

To my mind it has to be fuel related. Probably related to the carb tuning. I don't claim to be a good mechanic so its quite possible it is something simple related to the rebuild.

Also I should add that it ramps up quite nicely until about 2000 rpms. Then it bogs down - very noticeable change in tone as it gets up to 3000 where it tops out. If I go WOT the motor hesitates once or twice. My wife says she can hear pops from the exhaust. I just hear a very noisy exhaust.

Since I have already claimed to not be a mechanic. What is the danger of running up to high rpms with earmuffs on in the driveway? I probably should not put it into gear I'm sure but it seems to me that I should be able to get the same behavior out of gear as well as in. I simply haven't ran it up past 2000-2300 or so though for not knowing if it will blow my engine.

Thanks fellas.