Troubleshooting a Simple Pump That’s Not Holding Prime

One of the key benefits of the Simple Pump Deep Well Hand Pump is its ability to hold prime—meaning water stays in the system up to the weep hole, reducing the number of strokes needed to get water flowing again. But if your pump seems like it takes too many strokes to start delivering water, you might be losing prime. Here’s how to figure out what’s happening and how to fix it.

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💧 What Is “Holding Prime”?

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Holding prime means water remains inside the pump system up to the weep hole. When this works properly, you should expect:

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• 100CA: 13–15 strokes to get water

• 125CA: 7–8 strokes

• 200CA: 2–3 strokes

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If you’re seeing much higher stroke counts, read on.

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🔍 Top Reasons You’re Losing Prime

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1. Weep Hole Pipe Not Installed at the Top

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✅ The weep hole pipe must be the top drop pipe, just under the pump head. If it’s 50 feet down by mistake, the system will always drain to that depth. This is the most common installation error.

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2. Leaky Pipe Joint

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A cross-threaded connection or poorly sealed pipe joint can slowly leak water, causing the prime to drop over time—especially if the pump sits unused for days or weeks.

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3. Faulty Check Valve (Foot Valve or Ball-and-Seat)

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If the check valve at the bottom of the pump cylinder doesn’t fully seal, water will leak out the bottom and drain back into the well.

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4. Cracked Pipe

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Rare but possible. Shipping damage or stress during installation can cause hairline cracks that slowly leak prime.

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5.  Ball-and-Seat Design with Improper Stroke Calibration

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If your pump uses the older ball-and-seat system and the stroke is too long, the piston could press the ball aside and prevent proper sealing.

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🧪 How to Diagnose the Problem

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✅ Step 1: Check Stroke Length

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Mark the top of the pump rod with the handle up, then again with it down. Measure the distance. A full stroke should be about 9.75 inches.

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✅ Step 2: Check Output Volume

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Measure how much water you get per stroke:

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• 100CA → ~4.5 oz

• 125CA → ~8.5 oz

• 200CA → ~20 oz

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If volume is lower, you might not be getting full strokes or seals could be worn.

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📊 Multi-Day Leak Test

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1. Get water flowing

2. Wait 24 hours

3. Do full strokes and count how many until water starts flowing

4. Repeat every 2–3 days until results stabilize

5. Share the data with us—we can help pinpoint the depth of the leak!

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This test can determine if the water is draining to:

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• The static water level → faulty check valve (warranty-covered)

• A specific pipe joint → leaky joint or cracked pipe

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🛠️ How to Fix It

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• Check Valve: Contact us—covered under warranty

• Pipe Joint: Disassemble to the leaking point, re-thread properly, and reseal

• Crack: Replace the damaged pipe section

• Weep Hole Location: Reinstall the drop pipe string with the weep hole pipe at the top

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Need Help?

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Our team at Simple Pump is here to walk you through any of these troubleshooting steps. If you’re not sure what’s causing the issue, just give us a call.

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