Shurflo pump issue

[mol1jb]

Well here in Central IL the last few days sap have flown like crazy. The shurflo is up to 25" with no recirc line on 70 taps. It looks like Super sapper was correct in his assessment as I am only having the sap stop up before the pump in the morning after a freeze and the trees are not awake yet. Thanks for the help.

[TreeTapper2]

Did you find any sap frozen in the line near the pump?

[whity]

I don't mean to hijack this thread. I'm kind of having the same issue. We have a shurflow pump setup, but it's only pulling 4". Sap is flowing from the closest dozen trees but hardly anything higher. Is there a possibility the main could be plugged up? Or bad diaphragm? It worked amazing last season pulling a constant 15 inches but can't get 5 this year. I have walked all the lines several times and can't find any leaks. Like I said the closest dozen trees are flowing nice. Just not the rest

[maple flats]

whity, do you have a re-circulation line, if not, start there. It is also possible if it has been like this all year that a check valve is stuck, in that case, remove the pump and run warm clean water thru it, then hook it back up again. If the diaphragm got damaged, change it. You want to keep a spare on hand at all times.

[whity]

Thanks Maple Flats. We do have a recirc line but have not used it. There is a steady stream coming out from the closest trees, so the diaphragm is wet. I'll try the warm water flush. I have a few replacement diaphragms I can change if need be.

[Bill Southern NH]

Whity,

Another thing to look for would be if you have a strainer. I have 4 of the shurflo pumps running throughout the season, and it seems that every year after putting the pumps back together, the rubber o-ring in the strainer gets moved and pinched. It doesn't happen very often, but it happens to me almost every season with one of them. When it does happen, it won't get much past 3" of vacuum. I hope this helps.

Bill

[SeanD]

Awesome thread. I'm having the same EXACT problem as the OP with one of my pumps. I have sap backed up at the pump, 20" of vac, and little to nothing coming through. Then all of a sudden there is a surge and it moves a ton of sap in a big 20-second pull. I can hear it gush in the tank. Then it will stop and I can see sap back up in the mainline again.

Ironically, I do have a recirculation line, but I disconnected it because the mainline always seemed to have liquid enough in the line and I could get 25-27" without it. I had just thought the recirculation line was to keep the diaphragm wet and increase vac. With all the sap backed up at the pump, it seems weird that the recirc line adding more sap to the system would help - though it does seem as if it is vapor locked like BAP said.

Strange also that my other pump doesn't seem to have this problem. It's remote, but whenever I spend time with it, it seems to have a constant flow. The one difference between the two systems is that the one with a vapor lock and sap backup has a manual bypass valve to go to gravity. Whenever I clean the filter, I close the valve to keep vacuum in the line while I'm disconnecting it. Then when it's all back together and tight, I open the valve. I wonder if I'm creating a pocket of negative pressure on the upstream side of the pump when I do that.

The remote unit with no problems has an automatic bypass that opens when I shut things down to clean the filter. I lose all vacuum, but I wonder if that's a happy accident. Any aerospace engineers out there?

When the next flow gets going, I'll play around with it. First I'll get all vacuum of the line and see what the pump does from scratch. Then maybe reconnect the recirculation line to see if that helps.

Thanks for all the advice here.

Sean

[West Sumner Sugar]

Regardless of flow, I leave my recirculation line cracked all the time. When I say cracked I mean it, just enough to say its open. It seems to regulate the flow, keeps the gauge from fluttering and seems to keep things moving at a constant rate.