4.3 Merc TKS - 2005 Crownline

[lfunk11]

My boat has 250 hours on it, and I am having some issues with it this year. I only put about 20-30 hours a year on the boat because we are usually so busy with my son's tournament baseball over the summer. Anyways, the boat cut out a few times as I was getting it ready this spring with the muffs on but only a few times. I replaced the water/fuel separator but only had a few hours free today to get it into the water and docked at the marina (freshwater). So we did a few runs down the lake and the motor wants to cut out when I put it into gear unless I give it a little more revs then it worked fine. We went up and down the lake with no issues other than it wanting to cut out when I put it into gear at idle.

Then, as we were running about 3/4 WOT, it was hesitating at higher RPMS and I kept backing off the throttle until it died. I let it sit about 5 minutes or so with the blower on and the engine bay open. The boat started up again but I didn't push it and went pretty slow on the way back to the dock.

I realize there are numerous things that could go wrong, but it starts right up without any issues so no spark issues at least initially. I am thinking a fuel issue or dirty carb. I plan to clean the small screen in the fuel input line to the carb, but any other easy things I should try? I probably could rebuild the carb myself, but I may just take it somewhere because I just don't have the time. Would prefer trying whatever I can before pulling it right back out of the water and potentially losing a couple weeks of summer boating.

I did as much snooping around on the web and people say vapor lock in just about every thread, but it has issues cold and warm so I doubt that is an issue. Can I clean the carb enough while the boat is in the water to try to make it to the fall and then have someone rebuild the carb?

Any way to check if it could be a bad tank of gas? I put stabil in when I winterized it in the fall.

 

[NHGuy]

Did you change the fuel water separator? If not, that's your first place to go. Pour out the gas into a clear jar to check for water after the contents settle.
If there's water, you might be able to drive the boat til the water clears out of the carb bowl, but not always.
To avoid pulling the carburetor you could get a very small piece of tubing, (perhaps the nozzle straw from a can of spray lube) and attach it to a reservoir style hand vacuum pump. Those pumps are about $30 (Mityvac MV8000 online) This would work if that carb has a normal bowl vent that you could stick the straw down. J tube carbs can't be sucked out that way.

How recent are the spark plugs, rotor, distributor cap, and ignition wires?
Those are things you can do yourself.
Just be extra cautious to catch all fuel when changing out the separator.
Best suggested way is to put some oil absorber padding below the fixture, use a filter strap wrench to loosen it a couple of degrees, surround the filter with a ziplock baggie and remove it clean. It's a pain in the rear, but it's important to keep any fuel and fumes out of your bilge.
With the tune up stuff be sure you have removed power while working. Just take off the negative terminal or if you have a battery disconnect switch, power it off.

I'd say try to do what you can of this stuff yourself. Boat yards are busy this time of year and they ain't cheap.

 

[Rick Stephens]

I would put vapor lock way down my list with boats. With unlimited cooling the engine bay typically doesn't get hot enough.

I would suspect a bit of trash in your carb. 12 years old now, ever been gone through before?

I would also look at the shift interrupt switch and make sure it isn't kicking in. Not likely when it happens at certain throttle position and not at the same place, but your initial description of dying unless you add more throttle made me think of the interrupt kicking in because of a sticky lower shift cable.

Rick

 

[Bondo]

Ayuh,.... Check the Contents of the fuel filter on it now, for anything but good fresh clean gasoline,....

 

[lfunk11]

thanks for the responses

I changed the water/fuel separator prior to putting it in the water but did not look at the contents when I did because I was not expecting any issues. I will take a look at what is in there now to see if the gas looks OK.

I do need to change the spark plugs/distributor etc so I guess I will do that just to be sure. I saw the lower shift cable being a common issue, but have not had time to research that yet. Will take a look at that as well.

However, I am pretty sure it is a carb problem so I will try to poke around on the carb in my "free time." I have rebuilt carbs on my log splitter and lawn mower but those are simple carbs. Not sure I want to tackle a boat carb because my wife is already reluctant to go on the boat with this issue. I have not had anyone look at the carb in the 4 years I have had the boat, and I doubt the previous owner had any carb work done on the boat because it only had 150 hours on it when I bought it.

Hopefully I can get it running decent again to make it through the summer because I use it so little as it is. Then I can drop it off somewhere so they can properly rebuild and tune the carb.

I dread taking it to a boat mechanic now. The expense sucks, but how long they take this time of the year is what I really dread. Only had it there once, and it took 3 weeks for what should have been a simple fix.

 

[lfunk11]

I took it into get fixed any they replaced the distributer cap. I think that was all they did but they sent the invoice in the mail. I am now having a separate issue but I will post about that separately. The boat no longer wants to stall as I give it gas so one problem fixed. Only posting if this comes up in someones search in the future. I would see so many posts, but the people never posted the final solution.