My Black Series has two water pumps, drinking and general water: which one do I replace?

Answered by RV Parts Giant · Upland, CA · September 29, 2026

Short answer: Replace the one that fails the test, not both. Each pump draws from its own tank and runs on its own fused circuit, so switch them on one at a time with every tap closed: the bad one will not prime, will not build pressure or will not shut off. Check its inlet fitting for an air leak before you buy a pump.

Work out which pump has actually failed

Two tanks means two separate suction lines, and a pump always sits close to the tank it draws from, because the suction line has to be short. So the first job is to tie each pump to its tank. Follow the line from the bottom of the drinking tank and the line from the main tank; each one leads to its own pump. Each pump also has its own fused 12V feed, and tracing the wire from the fuse gets you to the same place.

Then test them one at a time:

Switch on only one pump, with every tap closed. A healthy pump runs briefly to pressurise the line and then stops.
Open a tap served by that pump. You should get steady flow once the air is purged.
Repeat with the other pump.

The pump that will not prime, will not build pressure, or runs and will not shut off is the one to replace. A pump that leaks from the head, or is noisy and weak, is also finished.

Check the fitting before you buy a pump

On a Black Series HQ, the stainless fitting on the pump inlet or outlet is one of the first things to check when a pump runs without delivering water. A loose or cracked fitting lets air into the line upstream of the pump, the pump loses prime, and it looks exactly like a dead pump. Look at the seal on the pump port and the hose end too. Owners replace the fitting when it drips, when the seal has hardened, or after a winter freeze cracks it.

Rapid cycling with the taps closed is different: that is usually a leak somewhere in that pump's lines, or an accumulator, rather than the pump itself.

Matching the replacement

The 12V pump we stock is the standard HQ unit, model SFDPI-030-055-42: 3.0 GPM at 55 PSI, 12V DC, 8A maximum draw, half-inch barb inlet and outlet, self-priming with an automatic pressure switch. Read the label on the pump you are taking out. If it matches, it is a straight swap. If it does not, match the flow, the pressure and the fittings of the old pump so you can reuse the plumbing.

The swap itself: pump off at its fuse, open a tap to release pressure, disconnect inlet, outlet and the two wires (note which is positive), unbolt, then mount the new pump on its rubber feet with an inline strainer on the inlet. Snug plastic fittings, do not overtighten them. If you cannot reach the pump, our answer on replacing a pump with no access panel covers the four ways in.

If it is the tank or the faucet instead

A pump that primes and holds pressure but gives poor water at one tap points downstream. We also stock the 16-gallon stainless drinking tank and the dual-outlet kitchen faucet with its separate filtered spout. Send us a photo of the pump label and which tap is affected and we will confirm the part before you order. Everything ships from our warehouse in Upland, California.