Mercruiser Wouldn't Stop - Then Would not Start Back Up Again ???

[kevinstan]

My carb appears to be the standard Mercruiser, and NOT the TKS.

I also agree that me hitting the kill switch might not have been what stopped it, it could have stopped on it's own and just at the same time I hit the kill switch.

Looking at the kill switch last night I saw two purple wires coming out of it. One solid purple and one purple with a white stripe. Do these need to be connected to close the loop and bypass the kill switch for testing? I have never seen purple wires from the kill switch before.

PORSCHEGUY: you mentioned you would be looking for a fuel issue, where would I start looking for a fuel issue at? Strange I do smell a pretty strong fuel smell around my boat in the driveway. Not sure if it is just the lovely hot GA sun, or if there is a fuel issue, but I will have to look into that also - not sure where to start looking or what to test.

Thank you to everyone so far for the comments. Anything that can help is greatly appreciated.

 

[alldodge]

You can bypass the switch at the helm by connecting from the key switch to any other purple wire connected to a gauge

 

[kevinstan]

I forgot one other thing - When looking last night there was a blown fuse. It was a 20 AMP fuse - black in the middle and blown. No idea what it goes to, and I will replace it - but I am not sure if that would have anything to do with my issue ? It was on the far bottom left looking at it from upside down under the helm.

 

[kevinstan]

AllDodge: That seems like the more complicated way to bypass it? Is there not an easier way by just removing both from the switch itself?

 

[RaceCarRich]

My two cents as an ex-owner of 2000 Bayliner 3.0L.

Run-on/Dieseling is extremely common with this motor per my research. First thing is to lower the idle but often it’s found that there is no sweet spot between so low it stalls during idle speed maneuvers and high enough to still run on. Timing should be confirmed to be correct. Next band aid is using fuel with a couple points more octane (that’s what I did). Last option is to idle for few minutes before shutting off to cool the motor down. This wasn’t practical if you were tubing under high load and had a rider fall off that wanted to get in without waiting.

Its possible the kill switch and the end of run on were a coincidence.

Run on can cause water to be sucked into the exhaust and cylinders if your flappers are gone as is common. Sometimes the last sputter causes the engine to spin backwards which causes the exhaust to suck. It happened to me on a lake and I had to pull the plugs and turn motor over to spit out the water. BTW getting shot in the chest with very hot pressurized water is not fun. It could have been worse as cold water on a hot valve could have cracked it.

You might want to pull the plugs. Are they wet or rusted? Did an electrode get crushed?

 

[TurtleTamer]

You almost certainly need a carb rebuild.

When I bought my boat, it was my first I/O and it dieseled at every shutdown. I almost thought it was normal. Eventually I found a sweet spot in the mixture screw that *mostly* cured it. I tried all the other stuff: idling for a while after a hard run, etc, but the only thing that wiped out the issue completely was a rebuild. It has not even hinted at doing it since.

If this was in fact a dieseling occurrence, you need to check your oil for water. If you sucked in enough to keep the motor from lighting off, you probably got some water in the crankcase. As stated, you'll also want to check the spark plugs.

I'm not a Bayliner Basher but you typically see owners that aren't looking to spend much, which is what attracts them to the brand. Unfortunately that also makes them not want to maintain them at times, so I suspect the carb has probably never been rebuilt and probably you'll need to do a complete tune-up as well.

 

[alldodge]

20 AMP fuse

The inline fuse should be connected to a Red/Purple wire and this is the ignition fuse. If it blows nothing works

AllDodge: That seems like the more complicated way to bypass it? Is there not an easier way by just removing both from the switch itself?

Many have a hard time getting at the kill switch, but if yours is easier at the switch, just do it there. Now if the fuse above is blown its not the kill switch

 

[RaceCarRich]

Mine continued to diesel even after a professional rebuild and then a second rebuild by me. Google how common it is on these motors.

 

[kevinstan]

The fuse is in a fuse panel. There are around 10 or 15 total fuses - and I have NO idea what this fuse goes to. I just saw that it was black and took it out. I will have to replace it, but it could be for the horn for all I know.

I am not thinking it's the carb at this point. I put the boat in, it started right up and ran for around 30 minutes before not starting back again. There was no sputtering or other issues that would lead me to think it was the carb. I am thinking more of a fire issue or gas issue.It will be another couple of days before I can dive into checking it out, so I am trying to get together a list of stuff to check. So far this is what I am going to look at:

First will be replacing the fuse... then I will go into this:

1) Kill Switch
2) Key Switch
3) Plugs / Wires - check for water inside
4) Ignition Coil
5) Fuel Pump

I am thinking I need to add a few more items in there but that is where I am going to start. Any other suggestions would be greatly appreciated. Thank you again to everyone that has given comments so far. Hopefully I can get this worked out and get back on the water.