Rough Idle & dying - Happened twice on last wekeend trip

[wakenup23v]

Boat has always been stable.2004 23 LSV with 380 Hammer Head ( I think - I belive the 2004 had a different number than newer years) On the last trip, boat was running fine but I noticed temp gauge wasn't working. During a boating break, I look around the engine and under dash to make sure cables looked ok for temp gauge. We then started the boat and was at idle speed and no problems except temp gauge still wasn't working. All of a sudden, it starts to idle real rough around 200 RPM's and then dies. Restart a few times and still does it. Also, if I start it with the throttle disengaged to tranny and try to give it gas, it does nothing like I'm not even giving it throttle but I can see the throttle moving on the carb. We let it sit 10-15 minutes and tried again and it worked fine. The temp gauge still wasn't working. It was fine for the rest of the day even when I shut off and restarted. The next day, we take off with no issues and the temp gauge is suddenly working again. On our last stop, we started up fine, backed out of spot and started idling forward. It suddenly started idling rough. I noticed the temp gauge wasn’t' working again. I was able to put along to try to make it to launch ramp and after a few minutes where it died a few times, it started running fine again. I had Perfect pass turned on (I made sure it was off the previous day when we had issues) and when I turned it off, the engine died. I restarted and it still ran rough for 30+ seconds and then suddenly started running fine. Any ideas? I was thinking temp gauge and choke was engaging because it thinks it's cold. Only problem with that is it would run fine later with temp gauge still not working. I don't see how PerfectPass would affect it since we could see throttle moving at engine.

[Steve B.]

Sure it has a carb?

Steve B.

[malibu2004]

I had a friend with a 04 do the same thing as minus the temp gauge. His distributor cap had a small crack in it.

[Lance B. Johnson]

I think that thing is going to be fuel injected......

When is the last time it had a tune up? IIRC tune up = 500 hours but I have had to do them earlier on a boat that was moored because of distributor cap corrosion.

[Jimmy Buffett]

When was the last time you changed your fuel filter?

[wakenup23v]

Thanks for the feedback. I was trying to keep it simple when I said I could see the throttle move at the "carb". And frankly, I’m not the much of a mechanic besides the typical oil change, impeller, spark plugs and filter changes that I do myself. I was thinking something electrical since it was odd how the rough idle stated the same on both occurrences (It was already warmed up, it started & idled fine but after only running within a minute, it started running rough and then went away without any rhyme or reason. I did plan on replacing the fuel filter. I keep the boat well covered when not in use but it's stored outdoors so corrosion with the distributor could be a factor. It has 275 hours and I haven’t replaced plugs or wires for 5 years. I would think if there’s a crack in the distributor, it would run rough when we hit rough water that bounces the boat around.

[malibu2004]

My buddies boat did it at all times. Idle, wakeboarding, surfing what ever. No rhyme or reason to it.

If you've never replaced the fuel filter I would say that's a good place to start.

If a filter starts to get clogged as you increase speed the boat will start to get slower even as you push the throttle. It will eventually get to a spot where it will continue to run but wont speed up as you push the throttle forward. In other words that's all she's got captain.

[JustinOSU]

Fuel filter

Engine timing

Throttle position sensor

Distributor cap and rotor

[Jimmy Buffett]

Could also be the Idle Air Control Valve, but my money's on the fuel filter. Change the spark plugs while you're at it.

[wakenup23v]

Throttle position sensor cross my mind also.

[Lance B. Johnson]

If its due for a tune do that first. It's never a good idea to guess at a problem and replace sensors actuators etc.

Tune up would include, d-cap and rotor, plugs, wires, fuel filter, pcv. Potentially a quick throttle body clean. I would rule that out before guessing at the other stuff. After the tune, then the problem should be diagnosed not guessed at.

[99response]

I'd bet on the cap and rotor, often overlooked iterm

[wakenup23v]

I'll start off with a tune- up since it could use it. Where do you guys suggest picking up d-cap, rotor & plugs, filters, etc? I suspect it's best to get marine parts versus autozone.

[Lance B. Johnson]

Bakes has always done right by me.

[malibuvlx02]

I've had the same thing on my 2002 VLX with the same symptoms you described. The shop I normally took my boat to for service reflashed the ECM with updated software that was outdated. The very next time I took my boat out I didn't have that problem anymore. I think it only cost me about $100.00 if that. Hope this helps.