Shipyard Isl. Marine Engine Parts - Ymaha HPDI 150 overheat warning problem.

Hey Andy, I talked to you on the phone about this problem earlier today. I've got a 2004 HPDI 150 Z150TXRC. I just got the boat, put it in the water and notice the tell tale was not spitting water and that the overheat light on the tach was blinking. So I shut it down, put it back on the trailer, and ordered some parts. Today I rebuild the water pump, replaced the thermostats, and made sure the tell tale wasn't clogged by running water up the water intake with the lower unit off. Put everything back together, put the muffs and hose on it, put the key in and before I cranked it the alarm sounded and the light on the tach was still blinking (cold motor). I cranked it to see if running some water through it would reset the alarm. I am 99.9% sure the water pump is perfect, but I got no water from the tell tale, so maybe it wasn't getting a prime on the muffs. That's when I gave you a call Andy and you told me to check the overheat sensor. Not sure I did it right but I disconnected the pink and black wire from the sensor at the connector before it goes into the main harness. I then put the black lead on the black wire and the red lead on the pink wire and got no reading on the ohm meter. I did this for both sensors, and if I remember correctly from what you told me and I tested it right, the sensors should be good? So if I've done all of that right, what else could be setting the overheat alarm off and causing the light to blink before the motor is even started? I know you said there could be a short between the sensor and the tach, I did not get a chance to check for that yet. And other than physically looking for a short I'm not sure how to check for that as I don't really know much about electrical stuff. ;? I do have an electrician at my disposal though. Is there anything else it could be if not a short? Is there a way to reset the display or computer? Any ideas would be greatly appreciated. Just got this boat 2 weeks ago and dying to get it in the water. Thanks!

Today I double checked the sensors, I am getting "0L or OL" on the ohm meter whenI check them. My electrician friend tells me this is what I should get if the connection/switch is open, which should mean the sensors are good.

I also stuck the motor down in a barrel and filled it up with water so I could run it properly instead of using muffs. I cranked it up and I am still not getting water out of the tell tale. I think I have some blockage because I am getting drips of water out of the tell tale and I got some sand and salt out of it while trying to snake a piece of fishing line through it, but I never got a solid stream.

The overheat light is still blinking on the tach even before starting it and while it is running. So I am assuming it is electrical since it is blinking before the motor is ever turned over... But could it be that the motor isn't getting sufficient water flow due to blockage and that is causing it to give the overheat light?

Another update...

I dropped the lower unit again and connected a hose to the water inlet coming from the powerhead. I turned it on and still no stream from the tell tale. So I used some compressed air and some wire and got a bunch of salt and sand out of the tell tale, then it started flowing real nice and I could hear the rest of the cooling passages filling up. I'm still going to take the impellar housing off and check and make sure everything looks good since I have it off. Then I will put it all back together and run it in the barrel again and see if I am getting water flow from the tell tale. Also going to pull both thermostats just to double check that both sides of the motor are getting water.

Not sure if this is going to fix the overheat warning light blinking before I even start the motor but if it does I will report back...

Might be related to a clogged up pressure relief valve on the back of the motor. It a spring loaded deal that keeps pressure from getting to high in cooling system. I replaced mine when the alarm kept going off at idle (Yamaha had an improved one for mt 01 model, rounded head). When it's clogged up water runs out it instead going thru the passages

Travis T

Well the water pump looks exactly as it should. I did take off both t-stats and held my finger over the tell tale and let the heads fill up. i got water from both sides. I just put the lower unit back on and I am waiting for the bucket to fill up so I can see if the water pump is indeed working and the tell tale is spitting.

I also discovered that the line running to the water pressure gauge was not connected so I got that hooked up. I followed as much of the wiring for the overheat sensors as I could looking for any exposed wire or disconnections and discovered nothing.

Travis - I did a little research into the poppet valve and think that might be my next stop if this doesn't solve the problem. If that doesn't do it I will reluctantly take her in to the shop.. Thanks for the help!

The water pump is working perfectly fine and the engine is running great. I let it run for a few to get it warm enough for the t-stats to open up. Didn't overheat, could put my hand on the heads no problem. Darn overheat warning light is still blinking...

Should I try swapping out the poppet valve or does it still sound like an electrical problem? If its going to be an electrical problem I would rather pay someone else to figure it out. I'm good with mechanical stuff, but pretty clueless with electrical.

Found this bit of information doing a search:

"your Tach is on the wrong setting if its just blinking above the overheat symbol at all times likely set to 4 stroke instead of 2 stroke....an easy fix with a simple dip switch in the back of the guage."

Could it be this simple of a problem? The boat is 20 minutes away at work so I will not be able to take a look for a few days. Anyone have experience switching the tach from 4 stroke to 2 stroke mode?

Is this a new boat to you? Has the water temp always flashed?

On the back of the gauge is the wiring for it. There are some single primary wires with bullet connectors. There is also 2 square plugs. Disconnect them both. Does the water temp indicator still blink with it running?

Andy

Andy,

Thanks for the reply. Yes I just purchased this boat. But I have figured it out! Turns out it was just the 3rd dip switch on the digital tach being set to 4 stroke all along. Just climbed behind the console and made sure the switches were Up (1st), Down (2nd), Down (3rd). Put the key in and the tach wouldn't power on... So I turned the battery switch on and turned the key on again (duh!) and the tach lit up. No more blinking overheat light and the oil level lights lit up also, I was also able to reset the trip hour meter to zero. Looks like everything is in good working order now. I guess I replaced the t-stats and impeller for nothing, but it doesn't hurt and at least I know they are good now. Thanks for the help and hopefully my ramblings will help someone else out in the future.