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Lesson of the Day


3 replies to this topic

#1 Swamp Fly

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Posted 26 November 2019 - 12:04 PM

So I was having some issues with my outboard.  With the boat on plane the motor would start to die at random intervals. Hitting the choke momentary would bring the RPM back up, lather/rinse/repeat until it went away.  It idled just fine.  Sounded like a classic fuel delivery issue.  I figured it was one of a limited number of things including bad fuel/collapsed line, clogged filter, bad fuel pump, or the carb needed cleaning. I've found it's best to start at one end or the other rather than the middle so I went for the low hanging fruit and began with the fuel line.  When I got to the primer bulb I noticed it did not feel right and there were some kinks in the line around it.  Why is it that they just can't seem to make a primer bulb that lasts more than a couple of years? So I bought a new one.  Fast forward more than a month and I finally get a chance to install it.  I went ahead and cut the kinks out and changed the configuration of the line so that the bulb is closer to the motor and the line won't kink as easily because I need to get to the bulb.  Started right up and idled better than before.  Great! I patted myself on the back but decided to test run the boat to make sure.  So yesterday I dropped the boat in and after a slight hick up (air in the line maybe) she ran great.  After about 7-8 miles it was like someone slammed on the brakes.  The choke didn't do anything but over fuel the motor just like expected when everything is correct fuel wise.  The motor was lugging.  I thought I had dropped a cylinder but I managed to get back on plane. From past experience I knew that the motor was incapable of getting the boat on plane with one cylinder down.  I could get 90% throttle or so but it took several minutes to get there.  To add to the fun it wouldn't drop all the back down to an idle which was a whole lot of fun in the 3/4 mile idle/no wake zone.  Needless to say I was pretty grouchy by the time I got back to the ramp.  This morning I messed with it some more.  After adjusting my carb to no effect I resigned myself to having to tear it apart.  I pulled off the oil tank (kind of a pain) and pulled off the baffle in preparation for pulling the carb.  I of course I go to toggle the butterfly (like that ever does anything but well you know...) and looked down the throat of the carb.  What the heck is that?  It looked like a blob of silicone or melted plastic was stuck in there.  So I pull out precision my pokey thingy also known as a screw driver, and proceed to pull out a very dead tree frog.  Well there's your problem!  Reinstalled the baffle and fired it up.  Since I screwed with the carb settings earlier I needed to readjust but Boom, good to go!

 

So the lesson of the day: Having a tree frog get sucked into your carb does nothing for the performance of your outboard...or for the frog!  That was a new one for me, never had that happen in the 35 years of owning boats.  So much for going green! No more bio fuel.

 

Swamp

 

P.S. And now you know my screen name is appropriate.



#2 Poopdeck

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Posted 26 November 2019 - 02:37 PM

I would have changed out the bulb before looking for tree frog to.

I also learned to stay away from aftermarket primer bulbs. Buy OEM bulbs at triple the price but they last a long long time.

#3 mikechell

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Posted 26 November 2019 - 02:56 PM

Two stories, both from people I helped.

Service Manager calls me: I've got a 225 that won't go past 4600 RPM.

Me:  Other than that, how's it run?

SM:  Fine, here's what we did ...

~~ He proceeds to tell me a whole list of fuel and ignition components that were checked or replaced.  I am telling him, at each one, that it wouldn't fix the problem, as described.  He finally gets irritated and asks why I keep saying things wouldn't work. (which he'd already proven during his "troubleshooting")

Me:  You said it runs fine.  At 4600, is it just not going any faster, or is it missing and chugging?

SM:  I said it runs fine! (getting a little angry)

Me:  It's got to be an airflow problem. 

~~Again, he starts through his list ... and I interrupt him.

Me:  Did you check the screen in the silencer case?

~~I hear him smack his forehead ... and a second later say, "I'll call you back."

To shorten the story, he found a 3/4 inch thick mat of dog hair from the boat owner's two border collies.  It was restricting the airflow to a value equivalent to 4600 RPM throttle opening. The computer was just fine with that.  The only value that was slightly out of range was the throttle position sensor.


Barbed hooks rule!
My definition of work: Doing something in which effort exceeds gain.
Ex-Marine ... quondam fidelis
 


#4 mikechell

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Posted 26 November 2019 - 03:18 PM

Story 2

Technician calls:  I've got a 225 that runs fine to about 3600 RPM, then it dies.

Me:  Completely, electrical and all? 

Tech:  No, it's still on.  Turn the key and it starts right back up.

Me:  3600 ... not a throttle position, but an RPM?

Tech:  How do I tell?

Me:  Run it with a load and without.  If it dies at 3600 in both conditions, then RPM.  If it dies at the same throttle position but two different RPMs, then throttle.

~~After a few minutes, he calls back that it's definitely RPM ... 3600.

We talked for several minutes, going over several electronic and mechanical situations that might contribute.  He's a good tech, been in several of my classes, and everything I came up with, he'd tried.  We then got to the final few hail marys.

Me:  So, we've decided it can't be electronic, fuel or compression problems.  That leaves air.

Tech:  I haven't found any problems so far, but I'll check some more.

~~After a while (two days, actually), he calls me back.  

Tech:  I found the problem ... when I took the silencer case off this time, I tilted and heard something rattle inside.  Turns out, there was a gearcase shim bag in there.

~~Someone had left one in there and it got sucked into the intake.  Sitting against the flame arrester screen, it laid flat through the low RPM ranges.  When the engine got to 3600, the airflow was sufficient to pull it up, onto the screen, shutting off all airflow to the engine.  Engine dies.  When the engine stops, the bag falls back, lying out of the way again.

 

Simple failures are almost always the answer.


Barbed hooks rule!
My definition of work: Doing something in which effort exceeds gain.
Ex-Marine ... quondam fidelis
 




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