Shurflo 4008 vac pump surging in the lines

[MassMapleNut]

First time out with a little 12V shurflo 4008 vac pump. relatively flat sugar bush. about 50 taps on it so far, four 3/16 lines ranging from 200' to 1000'. Plan is to add another 60 to 70 taps to it. The shorter lines are fairly flat, and the longer ones have about 30' of drop. I'm getting about 17" of vacuum at the pump and 12 to 15 at the end of the lines. Seems like this is either normal, or low, depending on which post you read. Today I had a pretty good run going, constant flow into the manifold, but I did notice that at times that the pump seems to sputter and the bubbles in the line go backwards, away from the pump, then it seems to catch and start drawing a vacuum again. Before I go buy more parts and pieces for a recirculating line, does anyone know if this is something a recirc line will fix, or have I got something else going on? I mainly went this route to avoid collecting buckets in a swamp, so I'm not terribly concerned with maximizing production (maybe next year though!)

Thank you!

[raptorfan85]

It's from not having a recirculation line. The pump sucks all the sap through, then loses suction from the natural air in the line, then rebounds and starts pulling harder. If you're not crazy about maximum production it's fine. Just how those pumps run. When you get a good hard sap run it won't do it as much.

[MISugarDaddy]

I had the same problem last year on one of my four pumps and discovered it was not the lack of sap, but rather a minute leak in the gasket of the Shurflo strainer I had installed just before the pump. I don't run a recirculation line because I have all my pumps located below the mainline so if sap is flowing, the pumps have plenty of sap to pump. I removed the strainer and connected the line directly to the pump and the problem went away. Apparently there was a flaw in the gasket on the strainer, because I installed a new strainer and the problem never reoccurred.
Gary

[SeanD]

I'll also add, surging a common problem with these pumps. The advice I've gotten in the past is that you should make sure there is a consistent slope to the pump. Any flat areas or dips can lead to backups and surging. I've taken care of that and still had surging, so I think there are multiple factors.

I also have the strainer before the pump. I clean it daily - and it needs it, especially when there are warm spells in the season which there always are. That said, I've caused my own problems with that. I've pinched or flipped the gasket or I just can't get a good grip on it reaching into the box.

Like Gary, I don't think it's a recirc. line issue. The sap it there. However, I am going to put them on this year and see if it helps. At this point, I'm trying everything I hear. It kills me when all that work in the woods goes to waste.

[foursapsyrup1]

I no longer get excited about surging. Faught it for years and didn't win. The sap comes out of the tree and the pump brings it in. Success.

[NhShaun]

Speaking of recirc lines, has anyone found a good stainless needle valve that works for this ? I'm struggling to find any affordable ones with good reviews.

[motowbrowne]

Speaking of recirc lines, has anyone found a good stainless needle valve that works for this ? I'm struggling to find any affordable ones with good reviews.

Needle nose vise grips worked great for me.

[holbrook hill farm]

Recently purchased a sap guzzler 401n and not having any luck finding a strainer or filter to put in before pump. Any leads or ideas, I am in Vt. Thanks

[Biz]

Recently purchased a sap guzzler 401n and not having any luck finding a strainer or filter to put in before pump. Any leads or ideas, I am in Vt. Thanks

Try US Plastics. They have several different types.
https://www.usplastic.com/search/?keyword=T-Strainer

[BAP]

Recently purchased a sap guzzler 401n and not having any luck finding a strainer or filter to put in before pump. Any leads or ideas, I am in Vt. Thanks

Tractor Supply sells them in their sprayer parts section. They carry them in 3/4”,1”, 1-1/2” pipe threads. Also, many online vendors sell them like Amazon and companies that sell sprayer parts.
https://www.tractorsupply.com/tsc/pr...s-steel-screen