Yamaha Outboard Fuel Injector Cleaning: The CDH Injectors

July 21, 2026

By Ryan Bates, Marine Mechanic

If we had to pick the single most common injector that comes across our bench, it's this one. Yamaha 4-stroke outboards are everywhere on the water, and they almost all run the same family of injector. We see them in sets of 4 off the four-cylinder motors and sets of 6 off the V6s, in every color, week in and week out.

What the CDH Injector Actually Is

The CDH injector is built by Nikki off a Bosch-licensed design, and Yamaha has used it across most of their 4-stroke outboard lineup for years. The part that confuses everybody is the naming. The exact same injector shows up as a CDH number (CDH210, CDH240, CDH275), as a Yamaha number in the 6-series 13761 family (68V-8A360, 63P-13761, 69J-13761, and others), and under a pile of aftermarket cross-references. Same physical injector, four or five different numbers on it depending on who's selling it. We've had all of them on the bench, so we can tell you they're the same part.

The Color Code: White, Yellow, and Orange

Here's the useful shortcut. The CDH injectors are color-coded by flow rating, and the color is how you tell them apart at a glance:

• Orange (CDH210) - the Yamaha F115
• Yellow (CDH275) - the Yamaha F150
• White (CDH240) - the Yamaha F200, F225, and F250

The rule that matters: match the color you pulled off. The colors mark different flow rates for different displacement motors, and mixing them up means the wrong amount of fuel in your cylinders. Colors and fitment can shift a little by model year, so if you're ever unsure, go by the injector you removed, not by a chart.

You can see real examples of each in our recently serviced database, with the before-and-after flow numbers off our bench: the CDH210 (F115), the CDH240 (F200/F225), and the CDH275 (F150), plus the closely related 63P-13761 and 6D8-13761 injectors off the smaller motors.

Why They Clog and Leak

Two failure modes, and we see both constantly. Clogging comes from ethanol fuel and winter storage. E10 gas absorbs moisture, breaks down over the off-season, and leaves varnish and gum behind that narrows the injector's spray holes. Leaking is the seat and pintle not sealing anymore, from deposits holding them open or from wear, so fuel dribbles when it shouldn't.

Marine injectors have it worse than car injectors to begin with, salt air, humidity, and a motor that sits for months at a time. Add E10 fuel and a New England winter and you've got the perfect setup for fouled injectors by spring. This is the same story we cover for outboards in general, but the CDH is the one it happens to most, just because there are so many of them out there.

What It Looks Like on the Water

The symptoms we hear about over and over with these:

• Rough idle at the dock - uneven firing, shaking, one cylinder that feels down
• Won't pull past a certain RPM - the motor runs fine down low but hits a wall up top and breaks up, because clogged injectors can't flow enough fuel when you ask for it all
• Hard hot starting - a leaking injector bleeds fuel down while the motor sits hot, so it floods or has no pressure to fire on when you try to restart
• Hesitation and a soft hole shot
• Excessive smoke from poor spray patterns
• High fuel burn as the motor compensates for uneven flow

The tricky part is these overlap with coils, fuel pumps, and a plugged fuel filter, which is why people throw parts at it. Our outboard running rough guide walks through the order to check things in so you're not guessing.

They Clean Up

The good news with CDH injectors is they respond really well to cleaning. We pre-test every one, run it through ultrasonic cleaning and backflushing to clear the deposits, then flow test it again to confirm it flows evenly, sprays right, and holds without leaking. Most come back to spec. The ones that came in leaking usually seal back up once the seat is clean.

You get a full report back with the before-and-after numbers on every injector in your set, so you're not taking our word for it. If one is genuinely too far gone, corrosion or physical damage, we flag it instead of sending it back with a cleaned sticker on it. That's the honest version of cleaning versus replacement: clean what's recoverable, and only replace what actually fails testing.

Watch Out for the Cheap Replacements

When a Yamaha owner decides to replace instead of clean, a lot of them grab the cheap set of CDH or 13761 injectors off eBay or Amazon. We see how that ends. A big share of those are aftermarket knockoffs, not genuine Nikki or Bosch, and they fail early or show up leaking out of the box. You pull the rail, install them, one won't run right, and now you're doing the job twice and buying twice. By then you've spent more than a cleaning or a genuine set would have cost, and you've burned a couple weekends on the water you'll never get back. Cheap replacement injectors are one of the most common false economies we see on these motors.

Cost

Cleaning is $30-35 per injector plus $15 flat round-trip shipping. A set of 4 off an F115 or F150 runs about $135 all in; a set of 6 off an F200 or F225 is about $225. New CDH injectors are $100-200+ each depending on where you buy and whether they're genuine, so a full set of six new can easily run $600-1,200. When cleaning has a strong shot at bringing them back, and with these it usually does, it's an easy call.

Which Yamahas This Covers

The CDH family covers the heart of the Yamaha 4-stroke lineup:

• F115 - orange CDH210, set of 4
• F150 - yellow CDH275, set of 4
• F200 / F225 / F250 - white CDH240, set of 6

The smaller motors, F70, F75, F90, and F100, use a related injector in the same 13761 family (like the 6D8-13761), and they clog and clean up the same way. If you run a Yamaha 4-stroke and it's got any of the symptoms above, the injectors are worth ruling out first. We do it as a mail-in marine service, so you can ship them from anywhere.