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.

[Super Sapper]

I manifold my 3/16 lines into a 1/2 inch header going into the pump. I have found that a good pitch into the pump on the manifold helps eliminate the surging. Any level spots or uphill in 5/16 or larger mainlines seems to cause issues with this.

[Biz]

The surging is probably from a leak. Pitching the lines well is something that is needed for 5/16" lines or mainlines but I have found that it is not an issue with 3/16" lines. I have a few flat 3/16 lines and they do not surge. Check your lines to see if one is flowing a lot faster than another or has more than 50% bubbles, that line is suspect. I have a pump station with a 6-way star fitting that was set up last weekend and had several leaks. I used a pair of needlenose vise grips with 5/16" tubing on the jaws, then went to each line and pinched it off. If the flow increases significantly in the other lines when one is pinched off, that line has the leak. Valving each line would be even better. The leaks turned out to be mostly simple things like an open fitting.

Dave

[MassMapleNut]

Thanks all for the info! I had a leak on one of my manifold fittings, that bumped me up to about 20" of vacuum. Also had not used teflon tape on the vacuum gauge threaded connections. Fixed those it was leaking enough to get me up to about 22". Could not get a needle valve to fit the 3/16 tubing, but put a check valve tap on the end of a 3/16 line and dropped it into the tank. So far seems to be working. 120+ gallons of sap yesterday and overnight and I'm running out of places to store it. That's about half of my total sap gathering last year... I'm gonna need a bigger boat!!!

[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.

[bmbmkr]

I've watched the sap coming in the laterals to my manifold and seen the same thing. Especially in the morning when the trees first thaw and start running. Another thing that compounds this is having laterals with varying amounts of taps and obviously length. Part of the fluid dynamic is the equilibrium finding itself an all of that tubing. Even though some of the laterals have more taps, they may have more space in between each tap. There's constant change inside that system as some of the trees produce more sap and some produce more gas. After an hour or so of the trees running, the equilibrium is pretty much constant, and the surging seems to diminish, until the tress and laterals start to freeze in the evening, you'll see the same thing again. Get the leaks in the tubing and the manifold fixed and like you said, you'll be looking for ways to store/boil more sap!! I've been running four to five shurflo 4008's for five years now, no recirc lines, and this year I let them run 24/7 on days with a good flow forecast. I added another 100 watt panel to each system 300 watts total now, and with the strainer screen in place, you won't have any ice damaging the diaphragms. I bought inkbirds last year and still haven't got them wired up. I haven't had to swap a battery all year with 300 watts running into my 15 amp charge controllers. I had to clean my strainers 2x a day a few wees ago with the 65F days we had back to back. That sure slimes up the lines in a hurry.

[RC Maple]

As a first timer with a 4008 and 5/16 lines this is great to hear of other's experiences. There was one day this year I have been able to get 15" vacuum at the manifold and that's it. I changed the strainer fitting and retaped that fitting this last week - I thought I was on to something. Not much difference. I do see surging as well but for the most part the sap and bubbles all seem to come in the right direction. Due to the lay of my woods, even though some lines are over my head in the low spots and I have tapped high in the tree at the far end of the line, I have almost no slope. I believe this is why I lose half of my vacuum and get no sap without the recirculation line open. What can I improve for next year?

1. Use a star fitting instead of the 1/2" SS manifold - too many possibilities for leaks.
2. I have 2 75 watt solar panels. It's not enough. I started today with 13.3 volts after being too cold to run yesterday. The sun shone all day while the pump ran and when I shut it off it read 11.7 volts.
Earlier this season, I would come out to see the pump not running and the temperature sensor not working either. I thought a connection might be bad but now I think the charge controller shut it off
for getting too low

The system has continued to put sap in the tank. It is just a pilot project this year. Of the 13 taps, only one of the trees has had a bucket on it before. One big silver maple I couldn't get anything to speak of out of it with buckets before so I don't have much history to compare the trees to. All the sugars are 10-11", so no big gushers there.

The vacuum stays right around 12-13" and the surging is minimal as long as I keep my 3/16 recirculation line end down in the sap and keep it restricted with a c-clamp inside the pump box.

[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/product/hypro-1-in-polypropylene-line-strainer-with-80-mesh-stainless-steel-screen

[holbrook hill farm]

Thanks, Amazon took care of things this morning.