Yamaha water pump question

[sparkiedent]

I have a 2005 Yamaha F90C on a 17' key west center console on a lift.
It has been running great, but a couple of weeks ago, when I started her up there was white smoke coming out of the back. I shut it off right away. Then tried again, and there was some smoke, but then the water came out of the pilot hole, the smoking stopped and the engine ran really well.
I took the boat out and there was no problem at any speed. After the last run, I had raised the engine, so thought perhaps that was the cause of the smoking.

The other day I tried to start her up and there was a little smoke, but the water did not come out of the pilot hole right away, and after about 15 -20 seconds I shut her off as I know I risk damaging the engine. (The engine sounded good for this short time.)

The weather has been a lot colder, and the water is colder than I have run the boat in the past if that makes a difference. There was some ice on the deck of the boat when I started working on her that morning.

The Questions:
How long can I keep the engine running without water coming out the pilot hole?
If I use the flush port and water comes out the pilot hole, then does that mean the water pump is bad?
I may have sucked up some sand/muck earlier in the summer, but did flush the engine after that.
Is there anything else I can check while she is on the lift?
Can you run a hose thru the flush attachment with the engine running in the water to try and shake things up? or will that just make things worse?
If I can't get water to run out the pilot hole, then I need to have the boat towed to the ramp don't I?

Thanks for any advice you can give.

 

[99yam40]

Re: Yamaha water pump question

if there was ice on the deck then the water in tell tail line may have been iced up also keeping it from flowing.

Did you try again after you had the water coming out with flush port.
It may have melted when motor warmed up

 

[robert graham]

Re: Yamaha water pump question

The water flow from the pilot hole is only to indicate water circulating through the cylinder/head....the hole can get plugged up with dirt, bugs, sand, mineral deposits, etc....try sticking a section of wire or heavy monofilament line (weed eater line) up into the hole to open it up...if still no water flow, then check water pump, thermostat and pressure control valve.....

 

[boscoe99]

Re: Yamaha water pump question

Well actually the water flow does not mean that water is flowing through the motor. It only means that the water pump is doing its job. Water is bypassed at the base of the block before exiting the motor via the tell tale outlet. It is not the same water that flows through the block.

Since you saw ice on the deck, I am betting that residual water trapped in the telltale system froze up and blocked the flow of water. Once the motor warms up the ice will melt and water will flow out the telltale again. Quite common actually.

Regarding the presence of smoke at start up, this can happen if the motor is left fully trimmed down. Oil on the back side of the piston can and will flow across the piston rings and get into the combustion chamber. That oil will be burned for a while after the motor is started and smoke will come out the exhaust. It is a good practice to store a boat with the motor slightly trimmed on the up side of straight up and down.

 

[sparkiedent]

Re: Yamaha water pump question

Thanks for your help. The weed eater monofiliment did the trick! I ran the hose flush attachment for about 5 min. Started her up and ran another +/-10 min, shut down and ran the hose flush again. (salty/brackish water) and she runs fine.

When I first stuffed the mono into the pilot hole, it came out with a coating of silt. Is there anything I should check where sediment and silt might accumulate when i get her off the lift?

Another question that is probably not related to the water pump but maybe to the smoking at start up.

The engine had been stored in the fully down position when I started today.( not anymore) She did smoke at start-up but that stopped right away. Unfortunately while I had her running in neutral on the lift, I noticed that some of the bubbles that came to the surface and popped had oil in them and there was a small but obvious oil slick around the engine.

After I put the flush attachment on, there was still some oil exiting the engine tho not as much.

How bad is this?
I can't tell you how useful this web site is. Thanks!

 

[99yam40]

Re: Yamaha water pump question

there are some insects that like to build mud nests inside little tubes, not much you can do to keep them out except put something over or into the opening in the tell tail and remove before cranking back up everytime. A piece of that weed wacker line would work and you could leave some sticking out far enough to easily see it to help remind you to pull it out

Are you sure it is oil and not fuel?
Could be a fuel leak or cylinder not firing properly and causing it to come out of the exhaust.

have you checked your oil levels lately to make sure it is not overfull/ making oil??

Motor needs to be tilted some when 1st shut down, after a while the motor can be tilted back down for storage

 

[sparkiedent]

Re: Yamaha water pump question

I am not sure if it is oil or gas. A tiny white ish drop comes to the surface and then quickly dissipates as a sheen on the water. My guess is oil as the drop looks like it has viscosity, but I wasn't able to actually grab one of the drops. Not sure what you mean by overfull/ making oil. I haven't checked the oil levels, but haven't added any oil since she was serviced last spring. How would she make oil?

will use your tip about keeping the weedwacker line in the hole.

Thanks

 

[99yam40]

Re: Yamaha water pump question

too much trolling, stat sticking open causing too cool of a motor , or wrong prop can cause fuel to enter the crankcase and dilute the oil on 4 strokes

Do a search and read up

edit
fuel pump on some will cause problems also