problem pumping

[matt]

I'm having a whale of a time figuring out my bilge pump problems. The problem is that it works sporadically; often after I've given it a shake. But I can't count on it. It always cycles, but doesn't always pump water w/enough pressure to discharge it.This weekend I replaced the pump (1100 gph) and the check valve (both the old ones and the new ones worked when not in-system), and checked the line for clogs (none!). So what could it be?I read the Rule pump instructions and that said if the hosing isn't directly vertical it could cause an airlock. I never noticed this problem before, but could that be it? If so, what's an airlock and how do I fix it?Two other facts that could factor in: 1, I've no vented loop, only a loop of the hosing at the discharge port; 2, I had some diesel in the bilge that probably cycled through at some point -- all clean, and new pump and check valve since). Any ideas greatly appreciated. Matt

 

[Allan Hadad]

Pump Problems

I've had similar problems. The pump would evacuate the bilge the first time when the discharge line was empty. After that it would run and run without picking up the water. It turned out that the combination of the spring in the check valve and the weight of the water upstream from the check valve was too much for the pump to push against. The amount the pump can push is also a function of battery charge and the resistance through the wires. The original Hunter wires are all copper, hence they were completely corroded clear up to the circuit breaker panel. My solution was to run new tin plated wire (seal all connections from water), install a check valve with only a 1/2 pound spring and put in a 1500 gph pump (more umph). I hope this helps.AllanAlchemie, H34SF Bay

 

[Steve Feinsilver]

bilge pump problems

I'm an expert on this, having had a 1993 h33.5 and now a 2000 h410, both of which I replaced bilge pumps on when they gave up. The wiring is highly suspect- my current switch gave up, and when I went to replace it noted that the wiring was multistrand and completely corroded (second season on the boat!). Incidentally, I finally figured out that the red and brown wires were reversed on the original installation.Bilge pumps are relatively cheap, and failures can be very expensive. Throw out the original pump and switch, buy good ones, rewire and keep all connections watertight and out of the bilge.s/v Breathless

 

[Clyde Lichtenwalner]

Pumping

I do not like check valves. Removed mine entirely. They fail to open when needed, obstruct the flow of bilge water being pumped, do not allow flotsom to pass, and leak slowly as they age meaning the bilge is never dry and the pump cycles, if only a few times per day.To keep the pump from cycling, I installed a second bilge pump that serves as a scavenger. Used the smallest computerized rule pump discharging to the smallest diameter hose (can't name the size right now). Water still runs back into the bilge, but not in enough quantity to turn on the big pump, which now operates from an elevated rule float switch. Use a new through hull next to the existing one or share the existing discharge. Big pump never turns on unless to test. As I view it, this is serious stuff. KISS, dump the check valve and have a system that works when it is really needed.