86 johnson 175 will not run in water!

[bgooden]

I took out my boat and when i got it in the water it didn't want to stay running. It will start but when i give it gas(not in gear)it dies.It runs great in the yard but not in water what gives?

 

[emdsapmgr]

Re: 86 johnson 175 will not run in water!

Normal situation. Most engines will run sitting on the trailer. It's another thing when the exhaust is 2 feet under water. The engine has to work harder to push the water out of the exhaust when at normal floating levels. You need all 6 cyls firing properly at that point.

 

[bgooden]

Re: 86 johnson 175 will not run in water!

What are some things i need to look for? What causes this?

 

[HighTrim]

Re: 86 johnson 175 will not run in water!

Start with the basics.

Check the spark and compression on each cylinder. Ensure that the compression is within 10 percent of each other and you get a bright blue snap spark that jumps a decent gap as well.

Let us know what you find.

 

[emdsapmgr]

Re: 86 johnson 175 will not run in water!

An spark checker will help to determine the spark quality on each of the 6 plugwires. An inductive timing light is helpful if you want to check spark when the engine is running and under load.

 

[bgooden]

Re: 86 johnson 175 will not run in water!

compression is good 90 per cylinder, spark is good and cleaned the carbs. going to take it out this weekend to see what she will do. i'll let you know what happened.

 

[bgooden]

Re: 86 johnson 175 will not run in water!

took it out and ran good but it feels like it wants to go in and out of gear. i found out when i got home that i forgot to move the pin by the tilt trim that stops the motor from going all the way down. could that be why it acts up? like it is sucking air or could it be a spun prop.

 

[emdsapmgr]

Re: 86 johnson 175 will not run in water!

If the engine was not trimmed properly, the prop can ventilate as you describe. Aluminum props are much less tolerant of incorrect trim settings. They don't have the cupping that stainless props do. Once you get the trim to function in it's full normal range, you should be ok.

 

[mikesea]

Re: 86 johnson 175 will not run in water!

Take the pin out ,you dont need it with TNT.If it sat not running for a time,the carbs probably gummed up.If you lay it up for winter etc.make sure you run a storage additive through with the gas.Run carbs out of fuel as well.Or ,I always tried to run my eng every month if possible,on a warm day ,that was when I lived in NY.

 

[bgooden]

Re: 86 johnson 175 will not run in water!

took it out last week after the carbs were cleaned again, still ran like crap in the water. i got home and noticed some gas in the air box so i took off the carbs and had a vacum line that had broke,could this be why it wouldn't run? it idols fine but when i give it gas it spit and spuddered like it was gettin choked out. then it sounded like the prop came out of the water or out of gear(i hope the clutch dogs are not bad)$$$$$not good!does any one have an idea?

 

[emdsapmgr]

Re: 86 johnson 175 will not run in water!

The prop you are running makes a difference on how it bites the water. What prop are you currently running? That engine has a fuel recirculation system on it. That system is designed to help the engine idling characterisitics by recirculating excess fuel which accumulates behind the reed boxes. The hoses can leak a small amount of fuel/oil if they deteriorate. Best to make sure all 6 of those hoses are intact and not leaking. You could go further and make sure the 6 one-way valves in that system are open and functioning properly.

 

[bgooden]

Re: 86 johnson 175 will not run in water!

where are the 6 way valves? i'll look later to see what prop it is..

 

[emdsapmgr]

Re: 86 johnson 175 will not run in water!

The six one-way "check valves" are part number 392988 on the intake manifold factory parts diagram.