Yamaha 70hp outboard idle shutting off

[TownsendsFJR1300]

If a operator does not regularly add RF or any other decarb agent to their fuel fill ups, what effect will adding it to the fuel after discovering the jets are clogged? Since it's a PM product, but it wasn't used to prevent, is its use also intended to breakdown accumulated debris within the fuel system?

I assimilate the purpose of use of RF/Seafoam to that of coating head bolts with anti-seize lube. It's used to prevent something bad from happening–in this analogy it's seizing. But had anti-seize not been used on head bolts, and they seize, you would not use an anti-seize product to loosen the head bolts. You'd use a product designed to loosen the seized bolt, such as PB Blaster or likewise.

You see where I'm coming from? I might be reading too much into the phrase preventative maintenance, in regards to RF. I've read numerous threads on this forum and others where the operator is asking for advice on how to solve their dirty fuel system problem. A common response is to add RF/seafoam, even double the dose for a better effect.

But this is where I get confused because the fuel system is already dirty, therefore the problem within the fuel system is past the point of "preventative".

Yours and others thoughts?

I see your point.

Its a preventive measure but if fuel is still flowing thru an orifice, it's very possible it'll clear it out (as it did in the link I posted above).

I've posted I run it REGULARLY in every gas machine I own. I run it in my OB with K100 (stabilizer). The engine does have low hours but I've never had to clean an injector, VST has never been apart, engine WOT is 6k @ 46 MPH.

IME, it works BETTER as a fuel system cleaner, vs carbon remover.

Now if a carb is fully clogged from sitting, no, RF alone isn't going to fix it.. Manual cleaning, etc needs to be done..

I have 10 HP Techumsah chipper / shredder that would NOT idle down, even after a carb tear down cleaning several times.. My BIL gave it to me-(no preventive maintenance) years ago.
While using the machine (WOT is 3600 RPMs), I added a LARGE DOSE of RF, NOTHING ELSE. Engine ran for about an hour (as I trimmed), by the time I was done, I could turn the idle screw down fully and get a normal idle...I didn't do ANYTHING ELSE...

Anyway, IME / IMO, using it regularly keeps from having other running issues.

I used to use Seafoam before I found RF. I do still use SF but for storing engines. Couple teaspoons in the cylinder, rotate, then leave at TDC (valves closed,to keep moisture out)

[greglwake]

I am planning to pull the carbs and take a look at what's inside. Since they are over 10 years old and I don't want things to get worse. I don't know what kind of maintenance was done on the carbs by previous owner. Hope to start working on this tonight. Thanks for the help and I will let you know how I make out.
Greg

[TownsendsFJR1300]

Just a tip, make sure you PULL both the idle and main jets and can SEE LIGHT thru them... (besides other cleaning)... Good luck..

[greglwake]

Thanks for the tip. Will let you know how I make out.

[robert graham]

My 2006 yamaha 70hp outboard motor shuts off some of the time when idling. Only been out a couple times this year since first start up. Engine starts up fine and runs great when in gear, just shuts off some times when in idle. Any idea what I should do to take care of this issue?
Thanks,
Greg

Remove idle jet screws(remember number of turns out from lightly seated) from top of each carb, spray carb cleaner in orifice and the a jet of air....may be a bit of debris in there....this worked on my C90 when it tried this shut off at idle trick...fixed it fine! Good Luck!

[greglwake]

Removed and cleaned the carbs last night. Was a little late for me to start up the motor to see how it would run. Carbs overall were pretty clean, the small amout of gas that was in the carbs did smell a little stale though. I cleaned everthing with carb cleaner and blew everything out. Hope to get out this weekend to see how the motor runs. Thanks for everyone's help on this issue. Will let you know how it runs after I give it a test run.

Greg

[TownsendsFJR1300]

Did you pull the jets completely out or simply spray while installed?

[greglwake]

Yes -- removed, sprayed, and cleaned the jets in all 3-carbs.

[zenoahphobic]

Whether a product is "called" PM or a full on after something has happened is often just the concentration of one or more active ingredient.

A PM "dose" is that which does not harm other engine parts but offers ongoing protection. A "cleaner" may very well start eating rubbers or plastics, or corrode metal if left in the engine too long.

This forum often has questions about what to use, what concentration and how long? e.g. cleaning out carbon, cleaning out water passages etc. as well as fuel additives to prevent varnish, stabilise alcohol mixes etc. etc.

[TownsendsFJR1300]

From the Yamaha site:

[scofflaw]

From the Yamaha site:

Well if yamaha says this is their biggest and baddest breakout snake oil product then who are we to doubt them. Order up....

[TownsendsFJR1300]

Well if yamaha says this is their biggest and baddest breakout snake oil product then who are we to doubt them. Order up....

Just did. Received another quart three days ago!

[greglwake]

Had the boat out on Saturday. Motor shut off once when first started up in the morning, but once motor warmed up, it ran great all day.
I believe the problem is solved. Thanks for all the help.
Greg