Boat not starting while in the water
 

Have an odd problem here - got a 1989 Four Winns boat that doesn't want to start while in the water.

It starts fine while on the trailer with water connected to it, but once its in the water, she doesn't want to start...

Thoughts? I was told to check exhaust flaps in the out drive, as they can break and there may be too much back pressure. The carb was rebuilt a few years ago, but it made no difference for the starting issue.

The motor is a 3.0 4 cylinder, and it has an alpha one drive.

Sent from my Nexus 5 using Tapatalk

Ran a quick check:
First, did you check for spark when it doesn't want to start?

Found this real quick:
Here's a whole page of WTF:
https://www.google.com/search?q=1989+Four+Winns+boat+that+doesn%27t+want+to+start+while+in+the+water.+&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb#channel=sb&q=boat++won%27t+start+while+in+the+water.&rls=org.mozilla:en-US:official

I have a chain saw that won't start in a tree or on a ladder. I know it doesn't help, just saying.

Rock,

Start by throwing a jigger full of gas in the intake and then try to start it. If it spits and sputters even a little bit, then you know you have spark and can investigate the fuel system. If it won't even spit, then start investigating things that might interrupt the ignition system when in the water. This allows you to take the correct troubleshooting fork in the road.

Hope this helps.

I could hardly recommend throwing gas down the carb and if it doesn't work then start working on the ignition/spark check. That's a recipe for an explosion. Don't handle gas then try to get a spark...

The op needs to post a bit more info for us to solve the issue. The neutral safety system suggestion is a great place to start prior to everything else as someone suggested earlier.

Are you kidding? I've done this as a troubleshooting step hundreds of times in my lifetime with no negative results. It's a very common troubleshooting step.

The only time it gets dangerous is when someone gets the bright idea to continue pouring in gas while someone is cranking the engine. THAT is when disaster can occur.

To do this safely, pour about a jiggerful of gas in the carburetor or throttle body, then set the gas container away from the engine then try to start the engine before the gas has a chance to evaporate. If it spits and pops even once, you know you have spark.

Not kidding. I had to help deal with the outboard mechanic who had with third degree burns over much of his head because he was dealing with gas and then checked spark... it's a bit safer to check spark by pulling a plug wire off the plug and hold the wire with your bare hand- you'll feel the spark and no need to deal with open gas.

Five will get you ten that the guy burned himself pouring gas in while cranking as I described. The only other way would be if he was close to the intake track while cranking. Not smart. In fact it's a good practice to slip the air filter back in place before cranking if you will be near the intake tract.

Checking spark as you describe will only verify that it is making spark. It won't tell you that it hasn't jumped time. My tried and true method is very quick and effective.

You can grab all the spark plug wires you wish. I'll pass.

X2 on that. Boats aren't like cars. Fumes can't accumulate in the bilge of a car.

You don't know this guys level of mechanical experience for one and personally, I'd check for spark by grounding a plug wire (phillips in the boot)......whether or not you've been careful in the past reminds me of Carl Wallenda.

As for checking timing...you're way down the quick check list......

Spark then fuel....that quick.

Not talking about adjusting timing, only knowing that it's close enough to start and finding it out quickly.

Sure there are plenty of ways to check spark, but a small amount of fuel, get out of the way and see if it spits. Nothing quicker and nothing more certain for moving along in the troubleshooting process.

IF this is a boat with limited ventilation in the engine compartment, then Kerry is right about being careful with gas.

Not me.

Any Winn has bilge pumps.....but not for this.
To get your jigger of gas you either need a can of gas or take off a fuel line....in a boat on the water. Can with way more than a jigger and not pouring like a bottle of vodka....in a boat....

Well what do you mean doesn't want to start? Turns over? Turns over and doesn't fire? Can you hear the spark? Do you smell gas? Does it fire idle and die?

Very good questions.

You're experiencing, what is known in most circles, Murphy's Law.