I bought a Simpson S2700H power washer with Honda GCV 160 engine for $20 at a garage sale. The seller said that it would stall out and they didn't have time to mess with it.
The engine starts and runs fine without the hose and gun attached. The pressure seems fine. With the engine off and the gun and hose attached, the water stream is fine. There are no apparent clogs in the gun or hose. When the engine is then started, it will run for 1-2 minutes, spray well, and then stall out. After this happens, it can't be pull started. The engine won't turn over because there is too much pressure built up in the pump/hose. If the trigger is pulled, a blast of water will shoot out. This relieves the pressure and the engine can then be pull started.
From what I have learned, the problem is that the unloader is constantly open, ie. not going into bypass when needed. So I removed the unloader valve and inspected it. It was not frozen, which I think usually leads to a constant bypass mode. The little shaft moves easily in and out without much force applied to it. The tiny holes between the o-rings do not appear clogged. I made a video of it here:
Anybody know how this unloader valve works? I assume water goes into those tiny holes and a pressure gradient must cause the shaft to move in or out.
Can I fix it or do I need to buy a new one?
The engine starts and runs fine without the hose and gun attached. The pressure seems fine. With the engine off and the gun and hose attached, the water stream is fine. There are no apparent clogs in the gun or hose. When the engine is then started, it will run for 1-2 minutes, spray well, and then stall out. After this happens, it can't be pull started. The engine won't turn over because there is too much pressure built up in the pump/hose. If the trigger is pulled, a blast of water will shoot out. This relieves the pressure and the engine can then be pull started.
From what I have learned, the problem is that the unloader is constantly open, ie. not going into bypass when needed. So I removed the unloader valve and inspected it. It was not frozen, which I think usually leads to a constant bypass mode. The little shaft moves easily in and out without much force applied to it. The tiny holes between the o-rings do not appear clogged. I made a video of it here:
Anybody know how this unloader valve works? I assume water goes into those tiny holes and a pressure gradient must cause the shaft to move in or out.
Can I fix it or do I need to buy a new one?