White Smoke/High Idle

[scfdbc9]

5.0 GXI, first trip to the lake this year. On first crank of morning, boat would rev super high and then drop off to super low idle before leveling off. Gradually worsened over course of trip. Never happened before this trip and Would only occur on 1st crank in AM. Had to refuel on lake a few times at their marina and also noticed white “smoke” from exhaust when we returned home and I ran on hose water in the yard. What am I looking for here? Water in fuel? Head gasket? Vacuum leak?

 

[scfdbc9]

Anyone?

 

[Scott06]

Anyone?

Hard to say off the info given, may not be an issue - may just be condensation in engine cooking off.

is this carbed or fuel injected. If concern is cooling system leak places to check are -

1. pressure test cooling system this will show a head gasket leak
2. possible water is leaking in between exahust manifolds and riser/or elbows- this is especially common in salt water where manifold and riser corrodes. Water can leak down into combustion chambers plugs would be clean if water is getting in there.
3. Is the engine getting hot? Could be a water flow issue and not getting enough water to cool the maifolds and exhaust system

There might be other

 

[Senior B]

So your boat if a GXI is fuel injected and if it's white smoke and not steam I would say your burning a little rich. The idle issue you speak of, I would first have a look at your Idle Air Control Valve (IAC). It's attached with two small screw to your throttle body along with your throttle position sensor. IACs are quite expensive but can often be removed, cleaned and put back on. Sometimes the plunger and the grove in the throttle body can get a little gummed up. The plunger moving in and out regulating the air is what controls your idle. There is also a vacuum line on top of your intake manifold that I believe goes to the MAP sensor that can cause your to be running rich (The white smoke) Check to see that's hooked up and not cracked. Good luck.

 

[scfdbc9]

thank you all!