Losing engine at low RPM

[green]

I am losing my engine at low RPMs. With the wind and current it’s made for a couple exciting docking attempts. Are there things that a novice can troubleshoot or should I get a boat mechanic to look at it?

50hp 4 stroke Honda

I purchased this 2005 26M last year and I believe it was serviced the year prior.

[WinSome]

It depends how engine diy you are. Was it working ok prior? If yes maybe some dirt or gunk. If that’s possible, heavily spray some sea foam into the air intake when engine is warm. Turn off for five minutes. Restart. It’ll smoke and then clear and maybe run better. ( two types sea foam -get the spray can for this purpose, liquid is for fuel tank)
Maybe increase the engine idle rpm’s.
Change fuel filter. Maybe do this first!

A search on this site will locate helpful info.

[green]

I’m not very diy but these seem like good places to start. (Googles where to find air intake )

Thanks for sharing some ideas. Will give it a try.

[Herschel]

You are no doubt more experienced than I was when I first got my 26X twenty years ago, but I did not know then that outboards would naturally stall when in gear at very low RPM's. I was shown that there was a minimum RPM (for my 2013 Yamaha 50 it's about 750 RPM) at which my prop was able to sustain before it forced a stall. That if I wanted to go slower than the speed 750 RPMs generated, I had to slip the transmission into neutral for a bit and coast. If I needed to speed up a tad, I had to bump it into gear for second or two. Like I said, I'm sure you know this already, but just in case. Maybe someone else can explain the engineering behind all of this.

[green]

That’s a good point. In my case I’m getting into neutral and also stalling. It’s only not stalling at about 2000.

[Russ]

You are no doubt more experienced than I was when I first got my 26X twenty years ago, but I did not know then that outboards would naturally stall when in gear at very low RPM's. I was shown that there was a minimum RPM (for my 2013 Yamaha 50 it's about 750 RPM) at which my prop was able to sustain before it forced a stall. That if I wanted to go slower than the speed 750 RPMs generated, I had to slip the transmission into neutral for a bit and coast. If I needed to speed up a tad, I had to bump it into gear for second or two. Like I said, I'm sure you know this already, but just in case. Maybe someone else can explain the engineering behind all of this.

Not the case with my Suzuki. I can idle in gear same as neutral. Has never stalled at idle.

[Be Free]

Is your Honda fuel injected or carbureted?

Low speed stall is not uncommon for carbureted engines. Different parts of the carburetor are used for low and high speed operation. It's easy to get the idle jet plugged up if the engine is not run for a while or if you get some bad fuel.

Stall on a fuel injected engine is a little harder to diagnose. Plugs, injectors, compression, engine control module can all be involved.

Is this a new problem or has it been coming on over time?
Did anything change? Fuel, altitude, recent work done on engine, anything else you can think of?
Does it always stall at low speed or is it intermittent?
Does it ever stall or stumble at higher speeds?

[green]

Thanks for the advice. Carbureted.

Popped off the cover and things looked clean. Gave 3/4 turn on this screw and it sounded better instantly. One more 1/4 turn and it stopped stalling at neutral and at low rpm.



I picked up some seafoam but didn’t see a need to use it.

[Be Free]

What is your RPM at idle? From memory, I think 850 is the idle setting for that engine. If turning the screw made it higher then you are just masking the problem.

[Herschel]

You are no doubt more experienced than I was when I first got my 26X twenty years ago, but I did not know then that outboards would naturally stall when in gear at very low RPM's. I was shown that there was a minimum RPM (for my 2013 Yamaha 50 it's about 750 RPM) at which my prop was able to sustain before it forced a stall. That if I wanted to go slower than the speed 750 RPMs generated, I had to slip the transmission into neutral for a bit and coast. If I needed to speed up a tad, I had to bump it into gear for second or two. Like I said, I'm sure you know this already, but just in case. Maybe someone else can explain the engineering behind all of this.

Not the case with my Suzuki. I can idle in gear same as neutral. Has never stalled at idle.

I did not mean to leave the impression I was stalling at idle in neutral. Just that if I operate it in gear at RPM settings below 700 or so, it will stall. Are you saying that your Suzuki never stalls in gear at any RPM? Just curious.

[NiceAft]

Thanks for the advice. Carbureted.

Popped off the cover and things looked clean. Gave 3/4 turn on this screw and it sounded better instantly. One more 1/4 turn and it stopped stalling at neutral and at low rpm.



I picked up some seafoam but didn’t see a need to use it.

Looks like you picked the correct carburetor on the first try.

According to the Honda manual, there are three carburetors.

[Russ]

Are you saying that your Suzuki never stalls in gear at any RPM? Just curious.

Correct. Never stalls. I often come into the slip idling in gear. Will pop it out of gear to neutral and back at idle.
Stalling while in gear doesn't sound normal to me. In fact, it sounds dangerous as an inexperienced captain might not understand to throttle up a bit.

[green]

What is your RPM at idle? From memory, I think 850 is the idle setting for that engine. If turning the screw made it higher then you are just masking the problem.

Just checked and it’s 1000 in neutral and just above and below in gear.

Before I turned the screw the engine sounded weak in neutral and as soon as I got a quarter turn it was better.

[Herschel]

Are you saying that your Suzuki never stalls in gear at any RPM? Just curious.

Correct. Never stalls. I often come into the slip idling in gear. Will pop it out of gear to neutral and back at idle.
Stalling while in gear doesn't sound normal to me. In fact, it sounds dangerous as an inexperienced captain might not understand to throttle up a bit.

This is really interesting to me. My idle RPM is about 700-ish. At that RPM, if I am in gear, I'm doing about 1 1/2 to 2 knots. I've got a 14" prop at 11-degree pitch. What kind of prop are you using? How fast are you moving when in gear at idle RPMs?

[Russ]

Some googling shows that motor idles at 950 +/- 50 RPM.

Another common issue seems to be ethanol in gas. I now seek out ethanol free gas which is also premium octane.

Old thread from 2008 re Honda 50 idle. The history on this site is amazing.
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