Epson L1800 DTF Printer Startup Stops With Two Red Lights Blinking: Cap Top Bubbling, Pump/Capping Station Issues, and What to Replace

Q: My Epson L1800 modified for DTF is bubbling ink at the cap top during startup, then the printer stops and both red lights blink. Ink pulls fine through the waste tube with a syringe, I already replaced the damper and ran cleanings, but it still fails. What part is most likely bad-cap top, pump, or an air leak-and what checks should I do before buying parts?

From what you described, there are usually two overlapping issues happening at the same time:

1. a capping station (maintenance unit) movement or timing problem (often the cap/pump "motor" not operating smoothly, or partially stalling), and

2. a restriction (clog) or sealing problem in the cap top / pump lines that causes pressure to build and then "burp" backward, which shows up as bubbling at the cap top.

Below is how these symptoms connect and how to test without immediately buying parts.

1) Why the printer bubbles at the cap top during startup

On the L1800, the startup routine relies on the maintenance unit to do a few things in sequence:

• Seal the printhead to the cap top

• Pull suction through the cap top (via pump and waste line) to prime/refresh ink at the nozzle plate

• Release the head at the correct time so the carriage can move normally

If the waste line is restricted, the pump is pulling but flow can't exit properly, so pressure/vacuum fluctuates. When the pump stops, that stored pressure can release backward and you'll see bubbling or a "push-back" effect at the cap top.

A key detail from your notes:

• You can pull ink normally with a syringe from the waste tube.
  That's helpful, but it doesn't guarantee the system is healthy during real operation. A syringe pull is steady and controlled, while the pump creates pulsed suction and depends heavily on cap top sealing and proper tube routing.

So bubbling can still happen even when a manual pull "seems fine," especially if:

• the cap top isn't sealing flat to the head,

• there's a partial clog in the cap top manifold,

• the pump is weak/uneven,

• or the tubes are pinched, kinked, swollen, or contaminated.

2) Why the printer stops and both red LEDs blink

On many Epson models (including L1800 family behavior), when the printer detects a carriage movement problem, it can throw a CR (Carriage Return / carriage jam) type error and stop the startup process-often with both red lights blinking.

In your case, one common cause is:

The capping station mechanism partially stalls or runs "weak."
It may still move, but not efficiently, meaning it may:

• fail to fully drop/release the head on time,

• stick mechanically,

• or not return to its "home" position reliably.

When that happens, the printhead can remain locked against the cap or wiper area, and the carriage can't proceed normally-triggering a CR error condition (carriage error).

So the two big suspects from your symptoms are:

• capping station motor / gear train timing or stalling, and/or

• cap top / pump path restriction causing pressure issues plus abnormal movement load.

3) Most likely faulty component (based on your symptoms)

Based on your description, the most likely culprits-in order-are:

A) Capping station assembly (movement/timing issue)

• A partially stalled motor, worn gears, sticky rails, or a binding mechanism can cause the head to stay locked too long, leading to a CR error at startup.

B) Clogged or restricted cap top / pump tubing (flow restriction)

• Bubbling suggests the pump is attempting to move fluid/air, but flow is not behaving correctly. If the tube is clogged or pinched, pressure builds and releases backward.

C) Poor cap top seal / alignment (air leak or uneven contact)

• If the cap top isn't sealing evenly against the head, the pump will pull air instead of ink, causing bubbles and poor priming. This can also increase load and cause odd behavior during startup.

A pure "air leak in the ink system" upstream (cartridges/tanks/lines/damper) is possible, but since you've replaced the damper and the symptom is concentrated at the cap top during maintenance priming, I would prioritize the maintenance unit side first.

4) Tests to run before ordering parts

Here are practical checks that usually identify the problem quickly:

Test 1: Inspect the waste line path for kinks, pinches, swelling, or internal sludge

• Remove and visually inspect the waste line from pump outlet to waste bottle.

• Look for ink crystallization, gelled pigment, or collapsed tubing.

• If you disconnect the waste tube from the pump outlet and run the startup/cleaning sequence (carefully, with a towel/container), watch whether flow is strong and consistent.

Test 2: Confirm cap top seal and seating

• With the printer off, move the carriage to the service position (unplug while parked if needed so it stays accessible).

• Check the cap top rubber lip: it must be clean, soft, and evenly contacting the head.

• If the cap is distorted, stiff, ink-caked, or not level, it can pull air and bubble.

Test 3: Listen for "screeching," clicking, or uneven motor sounds

• A screeching or strained sound is a big clue for gear/motor load problems.

• I made videos specifically for that screeching sound here:

  • Screeching sound video 1 (https://youtu.be/MjArYM-QnfU)

  • Screeching sound video 2 (https://youtu.be/TNOGd_1TtN6g)

Test 4: Check whether the head is being released on time

• Watch the sequence: does the head park, cap, then release smoothly?

• If it caps and then "hangs," or the carriage tries to move while still constrained, that strongly supports a capping station timing / stall problem that can trigger a CR error.

Test 5: Cap top suction test (simple but telling)

• With the head parked on the cap, use a syringe on the waste line.

  • If suction holds steadily, the cap is likely sealing.

  • If you can't maintain suction or it quickly breaks with bubbling, the cap seal/alignment or internal cap top manifold may be compromised.

5) What to replace (and what not to replace yet)

If you want to minimize unnecessary spending, I'd approach replacements like this:

Replace/repair first (highest probability):

• Cap top / capping station assembly if the rubber seal is questionable, alignment is off, or the mechanism feels sticky/binding.

• Waste tubing if it's swollen, kinked, or contaminated. Tubing is inexpensive and often overlooked.

Replace next (only if tests suggest it):

• Pump if flow is weak/pulsing abnormally even with clear tubing and a good cap seal, or if the pump gears feel stripped.

Hold off on (unless you find clear evidence):

• More dampers, head cleanings, or ink-side parts, unless you see persistent air ingestion upstream. Your symptom pattern points more to maintenance unit behavior than supply-side flow.

6) Videos that walk through the capping station steps

If you need help working on the capping station, these videos may be useful:

• Removing and Installing the Capping Station (https://youtu.be/_cZEkmgIZYc)

• Unclogging the Capping Station (https://youtu.be/WbY_6O1-w2c)

• Capping Station Maintenance (https://youtu.be/5yjq3ZN0qv8)

• Repairing the Capping Station (https://youtu.be/5UC2IMu9V90)

• Rewiring Capping Station Tubes (https://youtu.be/J9im3s8UJfo)

If none of those resolve it, we also have a detailed, exclusive step-by-step breakdown video (full disassembly to individual gears and proper reassembly) here:

• Capping Station Assemble/Disassemble Guide (https://bchtechnologies.com/products/video-capping-station-assemble-disassemble-guide-for-l1800-1390-artisan-1430-and-1400)

Addressing printer issues can be tricky because the problems are hands-on and can involve multiple interacting parts. Because of that, we're not able to provide remote troubleshooting, step-by-step repair instructions, or direct support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility: BCH Technologies Printer Repair Service (https://bchtechnologies.com/printer-repair-service). Due to high demand, everything is handled first-come, first-served, and it may take a few weeks before we can schedule your drop-off. Our services are set up to repair either the full printer or specific assemblies with clear intake steps. That said, we understand our rates aren't the cheapest, so we strongly recommend self-help through online research. A great place to start is YouTube and our channel homepage: BCH Technologies on YouTube (https://youtube.com/@bchtechnologies). Use the search icon next to "About" on the right side of the menu bar to find videos by keyword. I receive dozens of messages daily asking which video matches a specific issue, and after nine years of uploads it's difficult to remember every single one-YouTube search is the fastest way, and it may also suggest helpful videos from other creators.

Thanks again for contacting us, and thank you for supporting our work and our channel. I truly appreciate it, and I hope this points you to the right component before you spend money on parts.