I have a Rule RuleMate 750 bilge pump that seems to lose prime. With more than enough water in the bilge sump, the pump will just spin at full speed without actually pumping anything. If I remove the pump to check the strainer (always clean) and put it back, it works normally. I'm currently working on several rain leaks and with all the rain we've had, the bilge is picking up some (fresh) water. The discharge hose runs about 15' and goes up to gunwhale height and then back down to a thru-hull above the waterline. There is no one-way valve in the discharge, nor is there a siphon break. Should there be? I'm afraid that some time when I'm not aboard, if the pump is really needed, it may pull this and exhaust the batteries without helping. What do I need to do to resolve this? -Smitty
Bilge pump losing prime.
- Thread starter Smitty
- Start date
- Status
Get a new Pump?
Smitty, bilge pumps are self priming, if working correctly and if they are in water they should pump. Don't bother messing with it (unless a cartrige pump) which the Rule 750 is not. New pumps are not that expensive and you will be able to sleep at night. Fair Winds Cap'n Dave
Smitty, bilge pumps are self priming, if working correctly and if they are in water they should pump. Don't bother messing with it (unless a cartrige pump) which the Rule 750 is not. New pumps are not that expensive and you will be able to sleep at night. Fair Winds Cap'n Dave
how much head are you pumping?
It's not a prime issue. Most typical Rule pumps will not do much against a 4-5 ft head, even when new. Since you didn't indicate the head, it may be too great for a tired, semi-clogged pump. A new, larger one is the cheapest insurance you'll ever buy. Don
It's not a prime issue. Most typical Rule pumps will not do much against a 4-5 ft head, even when new. Since you didn't indicate the head, it may be too great for a tired, semi-clogged pump. A new, larger one is the cheapest insurance you'll ever buy. Don
"Head" in pump terminology concerns the
distance that the pump has to lift the water. As a complication, the length of the pipe, the number of elbows, are also given values for equivalant "head". You will find pumps rated for GPH (gallons per hour) At 5 feet, 10 feet, 15 feet, Etc. in each case the greater the lift the smaller the GPH value. At some point the pump will not lift water high enough to deliver any to the outlet.
distance that the pump has to lift the water. As a complication, the length of the pipe, the number of elbows, are also given values for equivalant "head". You will find pumps rated for GPH (gallons per hour) At 5 feet, 10 feet, 15 feet, Etc. in each case the greater the lift the smaller the GPH value. At some point the pump will not lift water high enough to deliver any to the outlet.
Sorry, I forgot ...
to mention that it's a brand new pump. The old pump (a Rule fully automatic 500) gave out at the end of last season. -Smitty
to mention that it's a brand new pump. The old pump (a Rule fully automatic 500) gave out at the end of last season. -Smitty
Loosing prime
If the pump is submerged then it is primed. If it is just not pumping and there is water completely over the inlet grating at all spots then the pump is bad. With that said, if the pump intake grating is close to the water surface in the bilge and the pump is tilted the part of the intake grating that is highest might be sucking air and causing the pump to loose prime. To test this, get the pump to loose prime and then pour in a bucket of water slowly. If the pump starts pumping you are golden. If it does not you need a new pump as it is probably sucking air through the pump body (crack) somewhere.
If the pump is submerged then it is primed. If it is just not pumping and there is water completely over the inlet grating at all spots then the pump is bad. With that said, if the pump intake grating is close to the water surface in the bilge and the pump is tilted the part of the intake grating that is highest might be sucking air and causing the pump to loose prime. To test this, get the pump to loose prime and then pour in a bucket of water slowly. If the pump starts pumping you are golden. If it does not you need a new pump as it is probably sucking air through the pump body (crack) somewhere.
Is the pump running backwards?
You may have accidently wire the pump backwards. The pump will work not very well. Bilage pumps may leave a inch or more of water in the bilage.Typically the impeller is submerged so no priming is requied. When the water is pumped down until the impeller starts to come out of the water it cavities and stops pumping.
You may have accidently wire the pump backwards. The pump will work not very well. Bilage pumps may leave a inch or more of water in the bilage.Typically the impeller is submerged so no priming is requied. When the water is pumped down until the impeller starts to come out of the water it cavities and stops pumping.
Thanks for all the help, now one more question ...
Is there a way to prevent the backflow when the pump shuts off? In my setup, it's about 12' from the pump to the high point in the discharge. When the pump shuts off, that hose full of water drains back into the bilge. Is there a way to prevent that? By the time the pump shuts down, the bilge is almost dry. After the backflow, there's a fair amount of water in it. It sure would be nice to prevent that. Would a one way valve in the dischrge help, or is it too big a risk for failures? -Smitty
Is there a way to prevent the backflow when the pump shuts off? In my setup, it's about 12' from the pump to the high point in the discharge. When the pump shuts off, that hose full of water drains back into the bilge. Is there a way to prevent that? By the time the pump shuts down, the bilge is almost dry. After the backflow, there's a fair amount of water in it. It sure would be nice to prevent that. Would a one way valve in the dischrge help, or is it too big a risk for failures? -Smitty
- Status