I have twin 1988 5.7l 320hp mercruiser racing EFI engines/bravos in my 272 sr1 Formula.
I purchased it a few weeks ago, ran on the hose and they ran rough and eye-burning rich.
I removed the fuel water separator filters filled new ones with Techron concentrated fuel injector cleaner( black bottle) ran the motors and now they run smooth start instantly and no rich smell.
Just thought I would pass this along. I have Never heard of this and I think it works

Most the time ultrasonic cleaning then flowed on bench is a world better than any additive, mainly the ultrasonic part. Thats why i made the investment and bought my own machine, Smitty

wow that,s good news,no more need for professional cleaning&flow testing equipment.i guess all the people having them professionally cleaned&flow tested were duped.thanks for this great information.

I started to unbolt/ loosen fuel lines and rail on one motor and I thought of this to save time. It made me think after doing it, that it absolutely worked. If I have more time in the future or feel it didnt give me good result then I will takem out and ohm out and clean/rebuild. Thanks for the info.

Gotta love it when you can save yourself a bunch of time money and headache. I had a similar experience a few years ago on a buddy's mpi that had similar symptoms. I used the same stuff and mixed a very heavy concentration in a small out board tank and ran it for about 5 minutes and it cleared up. It's still running great. Obviously there are other cleaning methods, but not always necessary, or convenient.

Smitty, that's awesome you're getting set up for that. Will you be able to measure flow as well with your rig?

Besides ultrasonic cleaning I will be able to measure flow, check for leakage when closed, spray pattern and flow at different rpms/ pw settings

Well It worked so far, well see. If I dont need to remove the injectors on this old boat then I wont. Like my silverado with 295 thousand miles on it. Never removed an injector on that and it gets 19 on the highway.

Thats great to hear. Saving money, headache and time is what Im hoping for.

Autos fair alot better with fuel than boats. Boats fuel see long sit times and condensation, water and corrosion in the fuel system that 98 % of autos will never see.

Many fuel injector table top machines come from China and are junk. There is some quality machines on the market. The ASNU table top machine is 10 K.

The Australians started this many years ago with table top testing machines called New Age.

Some have custom made machines and those do alot better at testing injectors along with cleaning them. RC Engineering is one of them who made an over the top machine(s).

Injectors are electrical and mechanical devices. A good machine can run all the tests and test for internal shorts among other things. You can check Spray patterns , leaks, flow volume, change fuel pressures, change rpms some up to 15K, check flow volumes and balance, clean and back flush injectors for the jist of it. The back flush is a feature to have but better to have it separate from the machine. Cheap machines do not have internal filters to filter out its flow testing fluid after it runs thru the injector.

Some services incorp a lab scope into their machine as well