Force 120 water output stops when moving

[gpointer]

1994 Force 120 on 17.5'Bayliner. At idle, water streams out the 2 output holes on the upper leg. Increasing RPMs causes even better water flow. When accelerating, water flow continues until the boat reaches plane, then the flow tapers off to less than a trickle, appears to stop completely. Horn went off at near full throttle after about 5 minutes. What gives?

 

[scotiany]

Re: Force 120 water output stops when moving

I would check the thermostat first. It could be a bad impeller but, I doubt it. When the boat is planing, most if not all cooling water is exiting through the motor leg underwater.

 

[gpointer]

Re: Force 120 water output stops when moving

Thanks Scotiany. That has saved much additional trouble.

 

[imported_bjs]

Re: Force 120 water output stops when moving

i had same problem replace the whole water pump not just the impeller the say that wont wear out thats bull because happened to me.you have to buy o e m not made in aftermarket.also make water passages are blocked off.mine was full of sand on the exhaust side of the motor.i fish at a sand pit.thats just something to look.i installed a water pressure gauge so i didnt have to look back to see if water was coming out.i think they are very important.

 

[bcbaylinerboy]

Re: Force 120 water output stops when moving

I also have a 120 force ..it's a 1994..and in the operations manual, there is a drawing of the 90/120 hp model and the 150 hp...on both of these it shows those holes as....."Idle Relief Holes".....i've never really taken note of the change if any in mine....but by the name....i would assume that they put out more while the engine is just idling....and less while full out..Maybe googling this term would give more insight...