Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

[Ballymac]

Hoping I can get some suggestions.
I have a fuel injected 2 stroke ?99 Saltwater 150 V6 Ser# SX150TXRX.
When I go to WOT & the boat (21? Parker) gets up on plane, after about 15 to 30 seconds the continuous beep will sound. I can shut the engine down & restart with no beep ? but once I get going again it will sound again. No beep at idle or while we wake board. Put the hammer down and it will sound after about 15 to 30 secs. I have the service manual. I?ve changed out the tstats & gaskets, pressure relief & spring looked good, I cleaned them and changed the grommet. I?ve changed the impeller and did not notice anything unusual with the water tube leading up the midsection. Also tested the temp sensor & thermo switches and all were within spec at multiple temps per the manual. In a test tank & only in neutral with some revving I cannot get the beep to sound, even after 40 mins. Back in the water, in forward, on plane, and before I even get to full WOT the continuous beep will sound. Checked the temp sensor & thermo switches right after the event and the ohms where within spec to the measured head temp via my pyrometer, which was only 155F ? discharge water was warm. The engine appears to be getting enough oil. Good prop. When the boat is on plane, the antiventilation plate is level with the water. My next move was going to be to remove the heads and check & replace the gaskets. Anyone have any suggestions on what else could be causing it?

 

[Inducted]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

Make sure you also rule out the oil system. Are you getting a low oil warning on your gauge? Check out your float system on your engine oil tank. Just an idea.

 

[Ballymac]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

No low oil warning, just temp. Seemed to be getting enough based on the test tank, but I will check out the system. Thanks.

 

[cr2k]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

Have seen cracked water tubes from the leg. Usually on the front side where you cant see it. Pull the water tube and check.

 

[Ballymac]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

Had a chance to check out a few things today. I need to make a correction to my eariler post. When the continuous beep goes off, the engine going into limiting RPM and the beep will continue for at least 1 to 2 mins. Whether at idle or engine off. Then the beep will cease. Like it's waiting for the engine to cool down or programmed to go off for a set time. Today, while on the water I checked the oil system, and sensors were working correctly. I checked the IAT sensor, which was good. I checked the Ox Density Sensor, good. Again checked the thermoswitches and temp sensor, good. Results have not changed when I get up on plane. Back on land, gonna start tearing it apart.

 

[99yam40]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

You said it does not go off as long as you do not run WOT.
What RPM are you hitting when the alarm goes off?

Do you have some instrumentation that indicates what alarm is sounding?

Have you tried to disconnect the temp overheat switches on the different heads to see if one or both are causing the overheat alarm?

Sometimes the remote oil pump cannot keep up with the oil used out of the motor tank at WOT if the in line filter is starting to plug up and restricts the flow

 

[Ballymac]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

When I'm at about 3K RPM it will go off. I am a bit concerned that the engine may be mounted too high. On plane, the water is at or just below the antiventalation plate. I did disconnected the thermoswitches (which tested good) and seen no effect. Also ran it without the temp sensor (also tested good) in the block, and had it dropped in the bottom cowl, still overheated. When I disconnetted the temp sensor with the engine running, it seems to race and not run correctly. I also tested the remote pump per the service manual and the flow was fine (the main engine tank has always been filled... by the pump. I'm working on taking the heads off. Lots of bolts & don't want to break any.

 

[Ballymac]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

Quick update. After a nice holiday, I had a chance to remove the heads. Under the head caps looked fine, but the heads were almost completely blocked. After a good cleaning and new gaskets it’s running awesome. Some helpful hints – follow the service manual and take your time, heat and PB Blaster are your friend. Work the bolts. It took about a day to remove each side – no bolts broke. Keep the bolts in order. Protect the cylinders & piston heads during cleaning. Keep them lubed. Clean everything thoroughly. Check heads to make sure they aren’t warped. And again, take your time.

 

[99yam40]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

Good to hear you are running again with no alarms.

But I do not understand how the motor would still signal it was overheating when you had disconnected the switches/sensors.

 

[Ballymac]

Re: Fuel Injected 2 Stroke ?99 Saltwater 150 V6 Overheat Problem

Never disconnected all at the same time. One by one they went off, thats how bad the heads were clogged.