Raw water Pump Flow Diminished

[Oceansailor]

Also check the intake hose. I once had a delamination inside the hose that prevented the flow when the vacuum increased.

[captain465]

A long shot, but for what it's worth............I once ran a commercial assistance boat (for recreational vessels) and had a similar problem. At idle, in neutral, the water flow was normal. However, when I put the boat in gear and started making way, the flow would diminish to the point of overheating the engine. After pulling my hair out trying to solve the problem, including back flowing the intake line, I had the boat hauled to check the intake clam strainer. It turned out that I had sucked in a short piece of yellow "caution tape". It was stuck in such a way that, if the boat was at rest, the tape would hang down slightly and allow full intake water flow. However, once I put the boat in gear and got underway, the tape would stream back over the intake clam strainer and block the intake! Back flushing would only push the tape out of the way, but the problem recurred when getting underway again. I wish I would have taken a photo of that situation, it was totally unbelieveable!

[Charlie]

Thanks for the ideas. The easiest thing for me to do was to recheck the strainer. It was empty.😕. Still on the easy side was back flushing the intake line. I thought about disconnecting the line at the water pump but decided not to. I disconnected the hose that went from the above water line strainer to the thru hull. I flushed it with water reconnected the lines.

From there I disconnected the hose to the out put side of the water pump, started the engine, and saw what the flow should look like. 😃. Wiped up a bit of water , reconnected plumbing and watched for flow out the stern. It was great. Engine has been running for half an hour and all is good.

[wolfgal]

Originally Posted by Charlie

Thanks for the ideas. The easiest thing for me to do was to recheck the strainer. It was empty.😕. Still on the easy side was back flushing the intake line. I thought about disconnecting the line at the water pump but decided not to. I disconnected the hose that went from the above water line strainer to the thru hull. I flushed it with water reconnected the lines.

From there I disconnected the hose to the out put side of the water pump, started the engine, and saw what the flow should look like. 😃. Wiped up a bit of water , reconnected plumbing and watched for flow out the stern. It was great. Engine has been running for half an hour and all is good.

Hey Charlie!

I've been watching this in hopes you'd find the solution. Of course, imagining all this is a bit tough for me.

In the end, where and what was the problem?

Was the problem in the hose on the output side of the water pump?

Or stuff in the water pump itself?

forgive me if this is a stupid question: Can stuff (that you backed into) actually get through the water pump and clog a hose?

Thanks!

[Charlie]

WG

I guess there was a blockage in the intake hose. By running water thru the intake hose backwards I must have pushed the crud out and it worked fine afterwards.