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Outboard Motor problem |
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Ranse
Orange Level Joined: 11 Mar 2016 Location: Tennessee Points: 773 |
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Posted: 06 Jul 2020 at 11:11am |
I have an old Johnson 33hp. It's been a reliable motor over the years. It got were it wouldn't idle, hard to start, choke and die. I rebuilt the carburetor and it seemed to solve those issues, but it didn't seem to open up quiet as much as before ( less RPMs ). I've had it on the water four times this year and each time it gets worst. Now at full throttle it runs half speed or less, and not much power. I used to pull the kids on an inner tube with this little motor. I can't understand why it won't rev up to full RPM. The adjustment knobs don't seem to do anything when you turn them. Could the fuel pump be going bad? Any thoughts appreciated.
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chaskaduo
Orange Level Joined: 26 Nov 2016 Location: Twin Cities Points: 5203 |
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I had an outboard that acted just like that. All said and done, the main bearing at bottom of engine was seizing up slowly till it seized up completely. Of course it was out on the lake where else.
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1938 B, 79 Dynamark 11/36 6spd, 95 Weed-Eater 16hp, 2010 Bolens 14hp
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Tracy Martin TN
Orange Level Access Joined: 11 Sep 2009 Location: Gallatin,TN Points: 10566 |
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Sounds like fuel pump and or restriction. HTH Tracy
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No greater gift than healthy grandkids!
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Dave H
Orange Level Joined: 11 Sep 2009 Location: Central IL Points: 3485 |
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I would first take the cover off and operate the throttle grip (motor off) and see if the throttle butter fly is going wide open.
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Lars(wi)
Orange Level Access Joined: 14 Sep 2009 Location: Permian Basin Points: 6695 |
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Using premium (super) gasoline and high quality outboard motor 2-stroke oil?
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I tried to follow the science, but it was not there. I then followed the money, and that’s where I found the science.
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desertjoe
Orange Level Access Joined: 23 Sep 2013 Location: New mexico Points: 13361 |
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Hey Rance,,,we got one of the best in the business,,right here on this forum,,ole JohnKC... I think he closed his shop when he went to work for the guvment,,,but he is a mountain of knowledge on them outboards. He chimes in every now and again, so give him a ring,,I'll bet he'll help you,,,,and,,,and,,he also knows you know who,,,,,,
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FREEDGUY
Orange Level Access Joined: 15 Apr 2017 Location: South West Mich Points: 5391 |
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I have a 40 hp Evinrude that ran as you describe, blown head gasket .
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Ken(MI)
Orange Level Joined: 14 Sep 2009 Location: Lansing, MI Points: 618 |
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First thing to check on an OMC acting like that is Point gap if it's old enough to have them, and I'm guessing it is early seventies? from the HP rating.
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Ranse
Orange Level Joined: 11 Mar 2016 Location: Tennessee Points: 773 |
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It's baffling, the motor starts good and doesn't sound to bad. It just acts like you have it at half throttle instead of full. It's not a linkage problem, the butterfly in the carb is opening fully. The motor is a 1969 model and it does have points. They're under the flywheel and a pain to get to. I think the gap is .040 but I not positive. I'm not sure how to check for a blown head gasket. I need to do a compression check. I believe it's supposed to be 100 psi. It could be time is just catching up with this outboard. You can get a head gasket for it, but I'm not sure if parts are available for a complete over haul.
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john(MI)
Orange Level Joined: 12 Sep 2009 Location: SE MI Points: 9263 |
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Do you have a gas tank with a pumper in the hose to get gas started flowing? Check the hose, bubble, and can for problems. If you have access to another fuel setup try that to see if you still have the same problem. You should also check out the connector and fuel lines on the engine up to the carb. On the Merc I had, there was an air leak at the pump bubble. Fortunately you could see bubbles coming out of the hose end where it connected.
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D14, D17, 5020, 612H, CASE 446
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desertjoe
Orange Level Access Joined: 23 Sep 2013 Location: New mexico Points: 13361 |
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Hey Ranse,,I'm thinking the point gap should be closer to bout .016-.020.,,,or the thickness of a piece of book matches,,,,,
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johnkc
Orange Level Joined: 22 Sep 2009 Location: KCMO Points: 714 |
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Hey Ranse, doesn’t that 33 have an adjustable high speed needle in the bowl of the carb? If so open it up a bit while under full load.
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I support the development of hybrid automobiles and alternative fuels as I need DIESEL fuel for my ALLIS CHALMERS!
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johnkc
Orange Level Joined: 22 Sep 2009 Location: KCMO Points: 714 |
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Also you had proper float level AND Float drop when you did the carb?
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I support the development of hybrid automobiles and alternative fuels as I need DIESEL fuel for my ALLIS CHALMERS!
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FREEDGUY
Orange Level Access Joined: 15 Apr 2017 Location: South West Mich Points: 5391 |
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That's how I determined the head gasket, low compression with a gauge and a "frothy" plug . Is your O/B a burgundy red by any chance ??
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Ranse
Orange Level Joined: 11 Mar 2016 Location: Tennessee Points: 773 |
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johnkc, Yes as you can see the card has a high and low speed adjustment knobs. I tried adjusting the high speed at fast idle, but not under load. It didn't seem to effect the motor one way or another. As for the float position, I didn't tamper with it. To be honest, I wouldn't even know what the correct position would be. I figured if it worked for over 50 years were it is, it should still work. To adjust the carb under a load, I will have to rig me up a tank. I'm not sure about removing the rope starter to get to the points. Is there going to be a spring unwind when it pops off? Thanks for your help.
FREEDGUY, No my motor has a white top and green lower unit. I think those red Johnsons are even older than mine. Maybe the 50's.
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DMiller
Orange Level Access Joined: 14 Sep 2009 Location: Hermann, Mo Points: 29661 |
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Could be getting a little gummed up or carboned up as well, reformulated gas is just NASTY on two stroke engines. Brother still has our grandfathers Brown/White Johnson 20, still runs great but he is running canned gas as a mix with two stroke oil when does take it out.
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Ken(MI)
Orange Level Joined: 14 Sep 2009 Location: Lansing, MI Points: 618 |
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As you please, but yanking the flywheel is about a 15 minute proposition if you have never done it before, if the head gasket was blown, you would know it, some outboards have perplexing problems, this isn't one of them. Point gap should be .018-.020". If playing with the carb settings has little or no effect, the problem is almost certainly ignition, those old OMC's are pretty bullet proof, I've drug them out of basements and garages where they have sat for decades, gave them a quick once over and a new pump impeller and they will run without fail unless they had a pre-existing condition.
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Ranse
Orange Level Joined: 11 Mar 2016 Location: Tennessee Points: 773 |
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Thanks for the help. New points are on the way. That's were I plan to start, then try adjusting the carb again. It's to hot to go fishing anyway.
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JoeO(CMO)
Orange Level Joined: 11 Sep 2009 Location: Cent Missouri Points: 2694 |
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I had a 50 HP V4 Evinrude back in the mid 60's that wasn't running right, a tune up including reed valves cured it
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Ranse
Orange Level Joined: 11 Mar 2016 Location: Tennessee Points: 773 |
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Well I've found one problem. I did a compression check on the outboard today and a have a striped sparkplug hole. I'm not sure if this is what been causing my trouble or not, because the plug screwed out fine, and the gauge screwed in fine. When I screwed the gauge out I could something wasn't right. When I finally got the gauge out it had threads on it. Now the plug won't screw back in. I figure I have two options, find another head or put a HeliCoil in it. I'm not sure that will work. Wil it hold compression? It's an aluminum head, can you even put a helicoil in aluminum?
I believe I did manage to get an accurate compression check. It was 95psi, which is a bit low. I believe it should be 100. The good news is both cylinders were the same. I'm hoping 95 is good enough. And I hope fixing the sparkplug hole at least gets to a point were I can adjust and fine tune the motor.
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FREEDGUY
Orange Level Access Joined: 15 Apr 2017 Location: South West Mich Points: 5391 |
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IMO, YES, the helicoil will work . Surprised the PSI wasn't closer to 120, but she's a "little tired" .
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Ranse
Orange Level Joined: 11 Mar 2016 Location: Tennessee Points: 773 |
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I never installed a helicoil before. I actually bought a kit that's for sparkplug holes and aluminum. It comes with it's own tap. After I got it home and read the instructions, you also need anti-seize and high temp RTV adhesive sealer, which does not come with the kit. I guess I'm going back to town tomorrow.
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Boss Man
Orange Level Joined: 03 Mar 2018 Location: Greenleaf, WI Points: 608 |
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They claim a heli coil will hold more in aluminum than the original threads. Ran my 81 Goldwing for about 30,000 mi with 2 heli coils in one head before I sold it. Been a long time since I worked on my dads Johnson short shaft, but I believe the rewind on the rope came off as an assembly. Fly wheel was easy to get off. Took me a few tries to figure out that the coating on the bottom side of the coil was cracked and thats why it would miss out on the lake but ran fine when tested in the drive way.
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FREEDGUY
Orange Level Access Joined: 15 Apr 2017 Location: South West Mich Points: 5391 |
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, that was NOT my experience at ALL . It came with it's own tap, but as far as the "chemicals", NOO !!
Edited by FREEDGUY - 11 Jul 2020 at 6:55pm |
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SteveMaskey(MO)
Orange Level Joined: 11 Sep 2009 Location: Wellsville, MO Points: 591 |
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Along with all the other suggestions check
the flywheel key. I had one that was partially sheared which makes the motor
out of time. I have also put a Heli coil in aluminum head on a auto and it worked
ok. I bought a kit that had the coil and tap |
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