[Yomoho]

I am struggling with an FXHO that intermittently sounds overheat alarms and falls into limp mode when almost-idling for 5-10 minutes after a normal speed ride of 15+ minutes.

When the alarm went off recently I observed exhaust gas (instead of water) being released from the port side pilot hole while idling in the sea. I disconnected the coolant feed hose from the outer exhaust joint. At idle RPM there was no water flowing out of the feed hose. When i revved up a little, there was a reasonable amount of water coming from the hose.

I took the ski out and fed tap water through the flushing port. There I got plenty of water from the port side pilot and the engine would cool just fine. So it seems like cooling water pressure from the jet pump is too low to push water up to the exhaust pipe jacket, and subsequently to the port side pilot at low RPM. Therefore, exhaust gas is creeping up the exhaust pipe's cooling jacket.

What could be a likely cause for this overheat condition?

 

[Yomoho]

Or, as a more general question:

Is there supposed to be a connection between exhaust and water paths that allows cooling water to flow into the exhaust or - vice versa - allows exhaust gas to get into the cooling water path?

The manual is not very clear on that part.

 

[Iovaykind]

Did you ever get to the bottom of this? I have the same issue on my 2004 fx ho. It feels like at idle, not enough water flow, leading to intermittent water coming out of portside pisser. After a long no wake zone, it'll start to steam, along with the starboard pisser too, then eventually overheats.

 

[Lee Taylor]

I would check for coolant blockage prior to the flushing intake. For instance, the cooling water intake filter (item 15) and its hose.

2007 Yamaha WaveRunner FX HO (FX1100F) Jet Unit 1 | Flemington Yamaha (yamahapart.com)

 

[Lee Taylor]

I have disassembled and cleaned my cooling system twice. The first time was because salt water was inadvertently left in the cooling system all winter because we were entirely focused on a suddenly broken leaf spring, trailer axle shifting, and tire jam against the frame. The second time was because of the ski being stuck on a sand bar and pulling the ski backwards pushed sand into the cooling system intake

Cleaning - Coolant Path, 1000cc, MR-1, Yamaha - YouTube

 

[paulveucasovic]

I am struggling with an FXHO that intermittently sounds overheat alarms and falls into limp mode when almost-idling for 5-10 minutes after a normal speed ride of 15+ minutes.

When the alarm went off recently I observed exhaust gas (instead of water) being released from the port side pilot hole while idling in the sea. I disconnected the coolant feed hose from the outer exhaust joint. At idle RPM there was no water flowing out of the feed hose. When i revved up a little, there was a reasonable amount of water coming from the hose.

I took the ski out and fed tap water through the flushing port. There I got plenty of water from the port side pilot and the engine would cool just fine. So it seems like cooling water pressure from the jet pump is too low to push water up to the exhaust pipe jacket, and subsequently to the port side pilot at low RPM. Therefore, exhaust gas is creeping up the exhaust pipe's cooling jacket.

What could be a likely cause for this overheat condition?

check thermostat it can get pluged with little stuff pull it clean it new gasket

 

[Iovaykind]

Wanted to follow up from my last post. I think in my case, the reason for the overheating at idle after riding for awhile is due to my pump cavitating. I used a GPS and realized I was only seeing 50mph top speed when the 2005 fx ho cruiser should be more like 58-59mph top speed. As such, at idle I think the pump is unable to push enough water into the cooling system. Then the engine overheats because even the portside pisser is not getting adequate flow, and that only is an indication that the exhaust (which is lower then the engine) is getting cooled. I will be changing my impeller and wear ring soon and will report back if 1. My overheating issues go away, and 2. If I gain back the original top speed of the ski.

 

[Iovaykind]

To follow up, changing the impeller and wear ring did not fix my problem. I am only getting 50mph still. I can idle all day long without overheating, but after running fast (I can keep going indefinitely), if I drop back to idle after that, the engine overheats and puts me in limp mode. I just can't seem to get a constant stream of water coming out of the portside pisser at idle. Flushing it has constant flow. Very frustrating cause I've tried looking for kinks in the coolant lines (thinking that at higher RPMs the pressure "unkinks" the lines) but nothing. I would imagine if it were related to clogged coolant passages in the head, it would overheat not just at idle after going fast? I guess with lower water flow when going idle, there could be heat soak from running fast and then result in an overheating block. I must be triggering a thermoswitch though because I get limp mode after running fast then idling. Just need to figure out why I'm not getting a constant stream at idle...

 

[Bmal]

Hey mate, did you end up solving this issue? I’ve got the same issue on my 2007 fx ho, thanks in advance!