Cleaning/Replacing fuel injectors on a 350 HO mag V8

[MrG]

Boat is - 2575 QCW with Mer cruiser 350 with Bravo 3 with like 2200 Hrs on the boat.
We now that our boating season is well over here in Ca it’s time to do some deferred maintenance. My boat has had a slight misfire while under idle for quite some time now we’ve been chasing it for what seems like a long time. Done all the traditional fixes. Cap/roter/wires/plugs/Idle filer/ well Now we think the injectors may be dirty or clogged after all I’ve run a lot of gas through that boat. Just wondering if anyone’s taking the injectors out of their Bennington any tips or advice?

 

[Remediation]

We have a 2008 2575 RCW with the 350 MPI Mercruiser I/O. We fought an engine miss for years, finally the engine lost power. After lots of research, found out the Mercury has a fueling cooling system on the motor. Their mistake was that they painted the inside of the system and eventually the paint flakes into the fuel and causes problems with the fuel pumps and injectors and every part of the fuel system after the fuel cooling system. It has been several years ago that we repaired the boat. Mercury did step forward and provide parts of the system as a "unstated" warranty. I had to pay for the labor which was a big bill but it made the boat useable.
2023 I finally gave up on the motor. Leakdown test showed cylinder issues. With a new similar Bennington costing 4 times what we paid for it, we had a new engine installed over the winter. 2024 was the first year in a while without drive train issues. It was a joy to pull the boat out and only request a winterize (1 of the challenges of the I/O) and a replacement pontoon bow eye because of a cruiser wake that ripped it off while we were docked. Looking forward to next season.

 

[PartyBarge]

Wow, you need to cross reference the year of your power package with when Merc discovered and fixed the fuel cooler issue (and if your motor has one). Also although the fuel filter is likely prior to the cooler, have you checked it for debris/ water ? (Assume that has been done, just covering bases) It can take some time to work water/stratified gas out of the system even with a flush.

If you are a DIY kind of guy, pulling and checking the injectors, fuel lines and cooler should not be a big deal. The cost of having the injectors cleaned may be a better value than replacing them.

 

[BigKahuna]

When we had our Mercruiser 4.3L V6 back in the day we had an engine miss for a bit. We tried every fuel injector/fuel system cleaner on the market. (Seemed like it) We were going to have the fuel injectors cleaned but our mechanic recommended we try a can of Seafoam a couple times a year first. Best product we have used. It got rid of the miss and never had to have the fuel injectors cleaned. Just my opinion.....

 

[Timdelta]

yamaha makes a injector cleaner only available at dealers. It fixed our issue.