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FL350 Carburetor Runaway?
http://www.pilotodyssey.com/PO/viewtopic.php?f=1&t=17663		 Page 1 of 1
Author:  MPDano [ Sat Oct 14, 2017 7:05 pm ]
Post subject:  FL350 Carburetor Runaway?
Guys,

Took the Odyssey FL350 for a spin around the block as I wanted to store it in my Toy Hauler. Idles fine, but when you give half throttle to get it to catch, I could feel the throttle get very light. I can let off and it comes down just fine, but when I opened it up to get some speed as my neighborhood is a little hilly, it went WOT (Wide Open Throttle). Kill switch was the only way to get it to stop.

My intake seemed fine and didn't see any cracks. Any thoughts on this guys?

Thanks,
Leo
Author:  canadian oddy [ Sat Oct 14, 2017 7:53 pm ]
Post subject:  Re: FL350 Carburetor Runaway?
That does sound like an air leak.
I would pressure test that Engine. Just my opinion.
Author:  MPDano [ Sat Oct 14, 2017 10:03 pm ]
Post subject:  Re: FL350 Carburetor Runaway?
canadian oddy wrote:
That does sound like an air leak.
I would pressure test that Engine. Just my opinion.


Can you give me more info on why to pressure test? Crankcase Seal leakage?
Author:  canadian oddy [ Sat Oct 14, 2017 10:29 pm ]
Post subject:  Re: FL350 Carburetor Runaway?
MPDano wrote:
canadian oddy wrote:
That does sound like an air leak.
I would pressure test that Engine. Just my opinion.


Can you give me more info on why to pressure test? Crankcase Seal leakage?


Yup I believe you have lost a crank seal or possibly a cylinder base gasket.
Is the carb tight in the intake boot ?? Don't laugh that happened to me.

Edit: I would do a fuel pump flow test first to rule out that it may not be delivering enough fuel and then the Engine leans out.
Author:  MPDano [ Sun Oct 15, 2017 9:43 am ]
Post subject:  Re: FL350 Carburetor Runaway?
Ok, did a little research on leak down testing. I can get a leak down tester tool or use compressed air direct, but make sure I remove the schrader valve from the hose connecting to the spark plug hole. Put on TDC (Top Dead Center) and listen for air.

Does this sound right for 2-stroke engines?

Leo
Author:  MPDano [ Sun Oct 15, 2017 10:21 am ]
Post subject:  Re: FL350 Carburetor Runaway?
Oops, just saw a 2 stroke leak down test and totally different. No more than 10 psi on these.

At least I am learning both ways as I own both 2 and 4 strokes.
Author:  canadian oddy [ Sun Oct 15, 2017 3:30 pm ]
Post subject:  Re: FL350 Carburetor Runaway?
Yeah careful what you do here. To much pressure and you will blow the seals out.
1) Remove the exhaust pipe and cap the hole with a plate and rubber seal (use an old inner tube).
In this plate I have a fitting for a low pressure gauge and a fitting to pump air in.
2) Remove the carb and plug that hole -- various items can be used. I made a plastic plug.
3) Plug vacuum hose coming from crankcase for the fuel pump.
4) Make sure piston is near bottom so it is not covering the ports and sparkplug is tight.
5) Put in 10 psi MAXIMUM !!!!
6) If you start losing pressure then spray soap water around to see if you can get bubbles to find a leak.

If I find the post with my test rig I will post it here.

Edit: here are some pics of my test rig. They are old ones and you will also note that I have the fittings on the intake and on the exhaust plate. I prefer the exhaust plate because you can't do the vacuum test properly on the intake side because of the reeds.

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Author:  MPDano [ Mon Oct 16, 2017 9:36 pm ]
Post subject:  Re: FL350 Carburetor Runaway?
canadian oddy wrote:
Yeah careful what you do here. To much pressure and you will blow the seals out.
1) Remove the exhaust pipe and cap the hole with a plate and rubber seal (use an old inner tube).
In this plate I have a fitting for a low pressure gauge and a fitting to pump air in.
2) Remove the carb and plug that hole -- various items can be used. I made a plastic plug.
3) Plug vacuum hose coming from crankcase for the fuel pump.
4) Make sure piston is near bottom so it is not covering the ports and sparkplug is tight.
5) Put in 10 psi MAXIMUM !!!!
6) If you start losing pressure then spray soap water around to see if you can get bubbles to find a leak.

If I find the post with my test rig I will post it here.

Edit: here are some pics of my test rig. They are old ones and you will also note that I have the fittings on the intake and on the exhaust plate. I prefer the exhaust plate because you can't do the vacuum test properly on the intake side because of the reeds.


Ok, removed the air filter assembly and pulled the carb. Pretty sure I know the source of the air leak. The little screw with a blade in the end that guides the carb piston fell out and a nice big hole for an air leak once throttle is pulled.

Going to tap it out and put a larger screw and grind the end so the piston has a guide, then jb weld it in place. If this doesn't resolve it, then it's a leak test for sure.

Leo
Author:  canadian oddy [ Mon Oct 16, 2017 9:39 pm ]
Post subject:  Re: FL350 Carburetor Runaway?
Oh my.
Are you sure it didn't fall inside ??
Why not do a leak down test anyways, they're fun, and then you will know the condition of your Engine.
Author:  MPDano [ Tue Oct 17, 2017 10:12 am ]
Post subject:  Re: FL350 Carburetor Runaway?
canadian oddy wrote:
Oh my.
Are you sure it didn't fall inside ??
Why not do a leak down test anyways, they're fun, and then you will know the condition of your Engine.


Very sure it didn't fall into the carb. I remember it being loose so I put some silicone on the screw head, apparently didn't hold.
Yeah, gonna source the pieces I need to make my own leak tester as well.

Leo
Author:  DMoneyAllstar [ Thu Oct 19, 2017 9:55 am ]
Post subject:  Re: FL350 Carburetor Runaway?
MPDano wrote:
Yeah, gonna source the pieces I need to make my own leak tester as well.

Leo


Good to hear. You shouldn't even fire a 2-poke Engine until you've leak tested it. Not that the leak test would've known your carb screw was going to eventually fall out, lol. But the "death rev" didn't get it's name for nothing. And the kill switch won't always "kill" a diesel'ing Engine. Run-away 2-stroke CVT buggies are not fun.

I cannot believe what people charge for a 2-stroke leak test kit on fleaBay. You can easily replicate a $100 tester for under $20.
Author:  MPDano [ Thu Oct 19, 2017 10:14 am ]
Post subject:  Re: FL350 Carburetor Runaway?
DMoneyAllstar wrote:
MPDano wrote:
Yeah, gonna source the pieces I need to make my own leak tester as well.

Leo


Good to hear. You shouldn't even fire a 2-poke Engine until you've leak tested it. Not that the leak test would've known your carb screw was going to eventually fall out, lol. But the "death rev" didn't get it's name for nothing. And the kill switch won't always "kill" a diesel'ing Engine. Run-away 2-stroke CVT buggies are not fun.

I cannot believe what people charge for a 2-stroke leak test kit on fleaBay. You can easily replicate a $100 tester for under $20.


Yeah, I did the repair to the screw. Put it all together, no more death rev but I still feel the throttle get very light on high rev. To me, sounds like it is still leaning. Do you have a list of pieces to make my own leak tester? I did see a video but parts weren't listed out.

I saw a seal kit for 2 seals on ebay. Is this correct?

https://www.ebay.com/itm/151748410951

Leo
Author:  MPDano [ Thu Oct 19, 2017 10:16 am ]
Post subject:  Re: FL350 Carburetor Runaway?
Carb screw repair

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