Epson ET-4850 #502 Ink Bottle Won't Refill the Tank a Second Time: Causes and Fixes

Question 

I have an Epson ET-4850. I bought the #502 replacement ink bottles (the $82 set) and successfully filled the tanks once. Now I'm trying to refill the tanks a second time, but the ink won't come out of the bottles anymore. There's still ink left inside the bottles, but it won't release any additional ink into the tanks. What should I do?

Answer

On the Epson ET-4850, #502 ink bottles use a "keyed" auto-fill valve system. The bottle is designed to only release ink when the tip is perfectly aligned and fully seated into the matching tank port. When a refill works the first time but fails the second time (even though ink remains in the bottle), it usually comes down to one of these common causes:

1) The bottle tip isn't fully seated or aligned, so the valve never opens

The #502 bottles have a spring/valve mechanism that opens only when the nozzle is inserted correctly. If the bottle is slightly angled, not pressed down fully, or not aligned with the keyed slot, it can look connected but still stay "closed."

Try this:

• Open the ink tank cover and the correct color tank cap.

• Remove the bottle and wipe both surfaces:

  • the tank's fill port/inlet ring

  • the bottle tip/nozzle area
    (Dried ink residue can prevent a proper seal or seating.)

• Reinsert the bottle straight down, keeping it vertical.

• Apply gentle, steady downward pressure-just enough to fully seat it.

• Do not squeeze the bottle. These are gravity-fed and squeezing can cause mess or air issues.

2) The tank is already at (or very near) the "full" limit, so ink won't flow

These EcoTank systems fill until they reach the designed "stop point." If the ink level is near the upper fill line, the system can't displace air properly, and the bottle may stop flowing even if you expect it to take more.

What to check:

• Look closely at the ink level window and the tank's upper fill line.

• If the level is very close to the top line, the bottle may correctly refuse to drain further.

• Sometimes the tank looks lower from an angle, but it's actually at the safe fill limit.

3) Venting/airflow is blocked, creating a vacuum that stops the bottle from draining

For ink to leave the bottle, air has to replace it. If something is preventing airflow-such as the bottle not venting properly while seated, or the tank area being closed off-ink can stop flowing.

Try this:

• Make sure you're filling with the tank cover open the way Epson expects during filling.

• Keep the bottle upright and let it sit for 20-60 seconds after fully seating-sometimes it starts slowly.

• If you recently cleaned around the ports, ensure there's no film, paper towel fiber, or residue obstructing the fill opening.

4) The bottle valve or nozzle may be stuck or clogged (rare, but it happens)

If ink has dried at the tip (especially if a bottle was stored uncapped or in a hot/dry environment), it can partially clog the outlet or interfere with the valve action.

Simple diagnostic test (without mixing inks):

• With the bottle capped/off the printer, inspect the tip for dried ink.

• If you have another empty #502 bottle of the same color/type, compare the tips.

• You can also test the mechanical seating by gently inserting the same bottle into a different tank opening only to confirm whether the valve "engages" (do not pour or allow ink transfer into the wrong color-this is purely a fit/seat check).

If the valve is defective, the bottle may need replacement even if there's ink inside.

5) Confirm the bottle type matches your model/region

Epson has multiple bottle numbering systems by region, and "looks similar" bottles may not open correctly if the keying is slightly different.

Confirm:

• The bottle is genuinely #502 and intended for the ET-4850 in your region.

• The color label and key shape match the correct tank.

Addressing printer issues can be a complicated affair because these problems are hands-on and depend on small physical details (alignment, sealing, tank level, and valve operation). Because of that, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility: Printer Repair Service (https://bchtechnologies.com/printer-repair-service). Due to high demand, we operate on a first-come, first-served basis, so it may take a few weeks before we can take your printer for drop-off. Our services are structured to repair either a whole printer or specific parts, with clear instructions on how to proceed. However, we acknowledge our rates aren't the most economical, so we strongly recommend self-help through online research first. You can start on YouTube or by visiting our channel homepage: BCH Technologies on YouTube (https://youtube.com/@bchtechnologies). To find the most relevant videos quickly, use the search icon next to "About" on the right-hand side of the menu bar. I receive dozens of questions every day asking whether we have a video for a specific issue, and with years of uploads it's difficult to remember every single one-so YouTube's search function is the fastest approach. It may also recommend helpful videos from other channels that match your exact situation.

Thank you again for reaching out and for your support. I hope the steps above get your #502 bottle flowing again and help you refill safely without spills or contamination.