What do you think happened

[Ray Ritchotte]

A month ago I replaced Impeller, housing etc. Ran the boat at the lake good water press (20 psi) and no problems. The next trip to the lake everything is running fine decided to call it a day and as I was returning to the ramp The water press. dropped,the warning buzzer sounded ,RPM's went to 2500 and the temp light came on. I went to neutral and shut the motor off and waited about 1-2 minutes restarted the motor water press went to 20 psi and everything worked just fine. I drove around the area of the boat ramp at different Rpm's and everything worked fine. When this happened I was at 4500 rpm's and the trim was at 3-4 on the bar graph. Do you think I might have hit a bag and it fell off when I stopped. I took the boat out the next week and fished for 5 hours and had no problems. 1991 150 Pro V, 327 hours on motor since new. Should I be concerned about the impeller ?

[robert graham]

Sounds like a plastic bag or seaweed or similar. If it ever does that again, stop boat/motor, tilt motor up to see what's on there. Plastic bags just float around under the surface for quite a while. I understand that in the Pacific Northwest that Kelp will plug water intake and fries more motors than anything else. I'm glad we don't have Kelp around here in the Southeastern USA

[99yam40]

lack of water from plugged off intake can harm the inpeller if it is blocked completly. I have had a small 35 Johnson melt the impeller down to a blob from seaweed blockage before I discovered the alarm was not funtioning. Just happened to look back and the tell tail was not there.
Would not hurt to pull and inspect pump just to be sure, but if the pressure is as good as before, things could be fine.

[ken52]

First place to always check is lower unit intake. If you have a temp guage not just a warning sensor I would think your temp will start to climb as the motor is getting starved for cooling. I've had seaweed and sand in a t-stat too which I check for blockage regularly too. Of course the previous failed to have screen replaced in lower unit which made it easy for stuff to pass through.