Last month we discussed how to diagnose and replace dampers. This month we will talk about your pumps. Pumps should be changed regularly as a matter of periodic maintenance, and this is something you can do yourself. If proper maintenance schedules are followed, it’s unlikely you will ever encounter a pump problem at all. However, pumps can sometimes fail earlier than expected, and it can be helpful knowing what to look for. Let’s discuss the causes of pump failure, how to diagnose them and how to replace them.
This article will cover the pumps used in today’s more common eco- and mild-solvent printers, like Mutoh Falcon Outdoor and Toucan series, Roland’s SC/SJ and VersaCam series or even the Mimaki JV2, JV3 and JV4 series printers, to name a few. These printers use a pump designed by Epson, which is based on a medical peristaltic pump concept (see Image 1). These pumps use a gentle cavitational action rather than an actual “pumping” action to draw ink into and through them. This is easier on the print heads than other designs. Recently, some manufacturers have changed to more robust pump designs that work better, last longer and are not as likely to leak. However, this article deals specifically with the older or current design, and if your printer is out of warranty, it’s likely this article applies to you.

Image 1: This is a Mimaki JV3 Pump. Notice the clear ink tubes, a nice feature of these pumps- let’s you actually SEE any clogs that may be in them. The short tubes go to the capping station and the long tubes are the waste lines. Notice that most of the pump is made of plastic.

Because there is no sensor or error detection for a failed or failing pump, sometimes it’s impossible to know there is a problem, other than to have it crash. For this reason, printer manufacturers recommend you replace your pumps (and dampers) usually around every six to 12 months. The dealer you purchased the printer from is generally responsible to make sure you are aware of the maintenance schedule, but this information should be included in your user manual, as well. If you have never had your pumps changed, and it has been more than a year since you purchased the printer, I would recommend you do it soon. It’s a matter of time before they will fail anyway.

Diagnosing pump problems are not always cut and dry. Missing nozzles or incomplete test prints are a first sign of trouble but can be caused by any number of other issues that would be impossible to cover in this article (air in the lines, capping station issues, ink or ink cartridge problems to name some). What I hope to do here is explain a bit about how pumps might fail, as well as some ways to diagnose symptoms; however, the focus of this article is how to replace your pumps as a matter of general maintenance and not necessarily in response to a problem. While the information in this article may be interesting for some, it’s not necessary to understand all of it if your ultimate goal is to simply replace the pump. It’s because some manufacturers consider pumps and dampers a “user replaceable” part that I felt it would be worth covering the removal and replacement procedures here.

As I mentioned, one indicator of a pump problem is decreased print quality or incomplete and missing nozzles on test prints, even after multiple cleanings. In other cases, people don’t find out there is a problem with the pumps until ink starts to leak from their printer. Pumps can fail due to a blockage or clog in the tubes or pump failure can be caused because the tubes within the pumps themselves eventually react with the ink and fail. Other times the tubes will simply rupture, caused by either a clog or the tubes themselves just failing due to a combination of reasons, including ink reaction and age (see Image 2). It’s no wonder pumps are considered a “consumable” item, like paper or ink, and in fact, are not always covered under the warranty periods by some manufacturers.

Image 2: OOPS! Looks like the cyan tube has actually burst, and you can see that ink has leaked into the printer. Chances are the pumps are old and are overdue for replacement or the printer developed a clog that resulted in tube failure. Sometimes improper tube placement can allow the tubing to abrade against the gears in and around the pump resulting in failure, as well.

Pump failure due to clogs are usually a sign that the printer has been left unused for long periods, and ink has probably dried in the tubes. If your printer has the option to perform periodic cleanings when left idle, I recommend you familiarize yourself with these options and use them. However, it is important to note that if your printer has been sitting for over a few weeks or has had infrequent use, it could be possible that your capping or maintenance station (the place where your print heads rest when not in use) has become clogged, along with your dampers, pumps and even your print heads. Replacing a pump is probably the least of your problems here, and if this is your case, I recommend you have a technician come in and assess your situation before continuing.

Failing dampers (see September 2008 DIY Part 1) can also cause some of the same symptoms of a failing pump. If you have not already checked your dampers, make sure you do that first. Just one more reason it’s also recommended you replace your dampers and pumps at the same time. It’s very possible that your ink flow problems are related to a combination of pumps and dampers, as well, and it’s worth taking them both out of the equation here. Nevertheless, presuming you have already ruled out the dampers, and multiple cleanings still do not produce results, it’s likely the pumps are at fault here, and we can continue. But if there is any question about your dampers, address them first before continuing. Besides, dampers cost less than pumps and in my experience will fail more often than pumps

Another thing to look at is your waste tank. If it is filling with ink, it means at least some ink is passing through your pumps. Also keep in mind your printer may have more than one pump. This does not necessary mean that all of the pumps are working properly. It means that if you have more than one pump, at least one is still working. You will have to inspect them further to determine which pump is failing. Again, maybe this is a good time to replace all of the pumps (and perhaps dampers) in the interest of regular maintenance - and skip trying to figure out which one went bad. Nevertheless, once we open the printer in the next few steps, it will be possible to determine which pump needs replacing by following the pump tubes back to the cap. For example, if your black head is the one having issues, locate the black cap and follow the ink line back to the pump you will want to replace. This should make more sense once we look inside the printer.

Now that we have discussed some of the reasons why your pump(s) might have failed and are fairly certain we have a pump problem on our hands, let’s take the covers off of the printer and replace them. Accessing the pumps will vary from printer to printer, but there should be minimal cover removal to access the pumps. I can’t describe how to open every model or type of printer here, just be aware that the pumps are almost always located just below and usually forward of the capping station (where the print heads dock). You will almost always find the cap (and pumps) on the right-hand side of the printer. Although some printers, like the earlier Mimaki JV3 models, have their pumps mounted in the rear of the printer. If this is the case, you may have to access those pumps by first removing the feed system and then removing the long panels in the back of the printer. Although I always recommend that you unplug the printer when servicing it, in this case, it is not absolutely necessary to do this.

Once you open the printer, you will see something like what I have shown in Image 3. You can see that each pump has two ink tubes going in and two drain tubes leading out to the waste tank. Each pump services two caps or print heads. Two of the tubes (usually the short tubes) will lead up to the capping station and the other two (longer tubes) will lead away to the waste tank. Make a note of which tube goes where and unplug them. Sometimes they will be attached to other tubes with a shunt or connector, and other times they will have fixed nozzles on a plate or the printer itself. Either way, make sure you note which ones you detach and where they lead. I also recommend you replace one pump at a time. That way, if you’re not sure what you just did, you can look at the other pumps for clues.

Image 3: Here you can see two pumps side-by-side. Notice that there are four lines going into the pumps from the capping station and four drain lines (bottom) leading to the waste tank. You will need to disconnect these tubes before removing the pump.

Detaching the pump is fairly easy; the pump itself will be held into place by a single screw (usually a phillips head), which we will need to remove next (see Image 4). Take the time to locate the securing screw now and remove it. Some printers will have gears that secure and actuate the pump. If they become loose, make sure you know how they were positioned. Gently remove these as you take note of how they were held into position. If you’re not sure, take a picture. I know it sounds silly, but sometimes it can be very helpful. In most cases, the pump will come away from the printer without any issues.

Image 4: Here you can see the single securing screw. Once you remove the screw the pump should be free. Take note that there may be gears that couple the pump motor to the pump, be sure to note how they are assembled and make sure you put them back the same way you remove them.

You should have the pump free now, so all that’s left to do is replace the old pump with the new one. If you see any ink that may have leaked under the pump, this is a great time to clean up as best you can. Now, simply install the new pump in reverse of how you removed the old one, making sure to reattach the tubes tightly both to the capping station and the waste tank tubes (see Image 5). Also, assure that everything lines up and fits right because many printers will have alignment pins or indentations that the base of the pump will fit into. It should almost “snap” into position. Some printers’ pumps fit differently than others, so just make sure you take a good look at how your old one was positioned for when installing the new pump.

Image 5: Make sure you reconnect the tubes tightly and securely to the printers capping and drainage tubing before replacing covers and operating.

Some things to consider when installing the new pump: be mindful of the tubing, as it can get caught in the gears that operate the pump. Just be sure to position the tubes such that they do not risk being abraded by any nearby gears but also so they don’t crimp or fold over either. Before replacing the covers, you may want to run a cleaning cycle or two to make sure that the pumps are cycling OK, and that’s it!

Some printers will also have a pump counter, like an odometer for your car that can be reset within the menu. You may need to consult your manufacturer for this procedure, but it’s not critical that you do this unless you’re getting a message to do so.
I hope I have not scared you too much about your pumps. Instead, I hope I have given you enough information to make informed decisions about your printers’ maintenance and ultimately empower you if you do start having problems. As we discussed, pump issues can be avoided by changing them regularly and not in response to problems. But if you do encounter problems now, you should at least have a better idea of what might be happening. In many cases, if your printer is out of warranty, identifying a pump issue yourself can at least save you a service call.
If you have any questions, please send me a line. You may e-mail your questions to gregorydaerr@at-yourservice.org and make sure to include SIGN BUSNESS in the subject line. We may print your correspondence in future articles, but due to volume of responses, we may not be able to answer them all personally. Letters may also be edited for space or clarity.

TIP:
Sometimes by gently massaging the pump tubes themselves, you can help clear any clogs in the lines. Another method is to insert a pipe cleaner or flexible wire into the tubes to try and clear any blockages.

(Click here to read Part 1 of this article series.)