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Help with clogged carbureator passage


frankd

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I've been working on a 9.9HP Yamaha 4 stroke outboard motor that was left with gasoline in the carb. First I pulled the carb and cleaned all the jets and then put it back together and attempted to test run it. There was gasoline running out the bottom of the carb. I opened up the accelerator pump and found the diaphragm was dried out and cracked. I replaced it and tried to test run it again. When I first started cranking it over, it would hit a couple of times, but not start. I helped it start by restricting the air intake and it was lean unitl it warmed up, and then ran pretty good. I pulled the carb again and found that there was no discharge from the accelerator pump. I pulled it apart 'again' and found that everything was working except the final discharge tube was plugged. I've been trying to clean out the restriction, but no luck. The discharge hole is very small. I soaked it in Berrymans B-12 for 2 days, and a friend had a stainless steel cable that had very small strands (.009") but I couldn't get that to go into the opening from either end. Any ideas on what else I could try? Maybe some magic potion that'll eat the crud out? A new carb is $400 or more.

 

I've added a couple pictures. The first one shows the discharge tube in the carb. throat....it's the first brass tube. The 2nd one is from the bottom of the tube. The opening here is pretty big by comparison, but the opening the fuel flows from is much smaller. I've tried to unscrew the tube so I could get better angle, but it doesn't budge. HELP!!!20200327_144902a.jpg20200327_144916.jpg

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I'm going t wait for Patch, the idea I have will work but dangerous and seeing as I have no idea who you are I will keep it to myself for a bit.

What you could try though, and you have to do this carefully, is to get some heat to the tip of the tube, either by using a soldering iron or a very small torch. Once it's hot, poke it out. Not too much heat or you might deform the orifice.

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An old school carb clean method is to mix lemon juice concentrate and distilled water 1/1 and heat to boiling on a hot plate. Dump the whole carb in and simmer for several hours. This can sometimes smell pretty bad. I wouldn't do it in the kitchen.

 

after everything cools down clean it up with non chlorinated brake parts cleaner. This method does not destroy the rubber bits that are not already completely unserviceable.

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Sorry I'm late checking in.

 

Thanks for the pics, the second one is cause for concern. All of us that regularly play in carbs have tuned their drivers to not damage the the slots. When we overturn the carb body to access the jet, the chips from the brass slot can and most often falls inside the jet! Now most folks will try to push the clearing tool thru the bottom up, and this at times jambs the chips inside. Replace the jet is a better choice

So best way to remove the jet is to prepare a water and cleaning detergent bring it to a simmer place the stripped down carb body into the pot, and cover... I remove the plastics like floats. After 10 minutes and using a better fitting driver, hold the body in a thick cloth or oven mitt, then remove the jet while still hot. What you did was expand the material.

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Patch,

 

The tube that is clogged is not available from Yamaha. I will customize a larger screwdriver and make it fit better, then I'll warm it in the cleaning solution/water mix and try to remove the tube. I 'assume' that you mean something like Mr. Clean or do you use dish wash soap?

 

Frank

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I used a High "E" guitar string to clean my outboard carbs. Both of my carbs got gunked up due to our crap gas and my inattention (I thought I'd drained them both).

 

The E string is a steel string and very small. Worked well on both the 2.5 hp and the 6 hp. Because the string is so small, I don't worry about hurting the brass jet. And I push from the outside of the jet up to dislodge the junk.

 

About $2 at any music store.

 

BTW, I also used regular carb cleaner...it seems to dissolve hard case junk better than Berryman's or Seafoam.

Edited by videoarizona
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I customized a screwdriver to fit the bottom of the tube's slot, soaked the carb body in a solution of cleaner and water, and then heated the water up to simmer on the grill burner. I pulled it out of the solution, and attempted to unscrew the tube. Nope, it wouldn't budge and then when I tried harder one of the slots cracked and fell away. Thanks Patch, a good idea but....

 

I PMed with MarCarl and he told me his method. It's a good method, but I decided that the potential of doing damage to the carb was too high and decided to look at other methods before I tried it. I decided to order the BerryMann cleaner that Puc suggested, and it arrived Friday. I also made up a Rube Goldberg attachment to blow air into the tube from the carb throat side. I took the shaft from an arrow, cut a piece about 2" long, drilled a hole almost all the way along it's length, and another small hole to intersect it from the side. Then I took a slightly larger drill and made a tapered hole that would seal better to the tube. I connected an air hose to it and soaked the carb for about 2.5 hours. I held the 'adapter' in place and had my wife open the air valve. The first time, nothing happened, but the second time I saw bubbles and carb cleaner come out of the inlet.

 

 

When I refilled the tube with carb cleaner spray and blew air from the bottom up through the tube, my wife saw something interesting. The tube outlet wasn't on the top end of the tube where I 'ASSUMED' it was, but on the inside side of the tube spraying in the direction of normal air flow. With the discharge hole in this location it occurred to me that the tube had to be in it's present roation after it was installed in the carb body. I wonder if the tube was screwed into the carb body because that would mean that the thread starting position would have to be repeated on every carb. I wonder if it's possible if the tube was pressed into the carb body with an interference fit. That would make it easier to duplicate the rotation of the tube in each carb. That would also mean that you can't remove the tube from the body to make it easier to clean. If so, this is a throw away piece, like a lot of things. One more thing. Yammie must have had problem with this tube clogging because the accelerator pump inlet in the float bowl has a fine mesh screen on it. When I took it apart the first time the screen was laying in the bottom of the float bowl. The screen has a rubber grommet that holds it into the carb body and over the years the rubber had dried up and shrunk. The new screen fits tightly......now.

 

I plan on putting the carb back together this morning. There is a small plastic plug with an Oring that pushes into the carb body. If I have a replacement Oring in one of my kits I may even get to try out the carb in the driveway. If I don't have a suitable replacement I'll have to order it. The original Oring has dried up and isn't tight in the hole it goes into.

 

Thanks everyone!!!

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One thing I learned early on is that what one man ensembles another can disassemble;)

Having said that tho there are times its just not worth the effort.

 

When you first posted the pic of the tube jet I took pause to admire her physics. Yes the port would have to be downstream;

the cylindrical shape dictates her performance and the height ensures even minimization all the way to the valve. That greatly reduces drag and air/fuel separation at its give rpm and flow rate (the bore wall effect).

May not seem like much but from the butterfly's perspective and where the Plate will already be parallel to the bore, a nice mixed flow across the plate!

(on a side note, some time ago a hobbyist playing with flow principles designed and machined the needle jet with a lift which greatly increased what again is mentioned above)

 

Of course servicing would be best done thru a heated chemical cleaning if possible. As for installing it, well there are different ways to accomplish that. Because of what is mentioned above the seal around the jet must be 100% so contraction of the body makes the most sense to me.

Also should such a jet design rotate or come off true center to the air flow then, it would cause a reverse pressure down the tube to the bowl rendering the design useless.

Thanks for sharing the problem;)

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I customized a screwdriver to fit the bottom of the tube's slot, soaked the carb body in a solution of cleaner and water, and then heated the water up to simmer on the grill burner. I pulled it out of the solution, and attempted to unscrew the tube. Nope, it wouldn't budge and then when I tried harder one of the slots cracked and fell away. Thanks Patch, a good idea but....

 

I PMed with MarCarl and he told me his method. It's a good method, but I decided that the potential of doing damage to the carb was too high and decided to look at other methods before I tried it. I decided to order the BerryMann cleaner that Puc suggested, and it arrived Friday. I also made up a Rube Goldberg attachment to blow air into the tube from the carb throat side. I took the shaft from an arrow, cut a piece about 2" long, drilled a hole almost all the way along it's length, and another small hole to intersect it from the side. Then I took a slightly larger drill and made a tapered hole that would seal better to the tube. I connected an air hose to it and soaked the carb for about 2.5 hours. I held the 'adapter' in place and had my wife open the air valve. The first time, nothing happened, but the second time I saw bubbles and carb cleaner come out of the inlet.

 

 

When I refilled the tube with carb cleaner spray and blew air from the bottom up through the tube, my wife saw something interesting. The tube outlet wasn't on the top end of the tube where I 'ASSUMED' it was, but on the inside side of the tube spraying in the direction of normal air flow. With the discharge hole in this location it occurred to me that the tube had to be in it's present roation after it was installed in the carb body. I wonder if the tube was screwed into the carb body because that would mean that the thread starting position would have to be repeated on every carb. I wonder if it's possible if the tube was pressed into the carb body with an interference fit. That would make it easier to duplicate the rotation of the tube in each carb. That would also mean that you can't remove the tube from the body to make it easier to clean. If so, this is a throw away piece, like a lot of things. One more thing. Yammie must have had problem with this tube clogging because the accelerator pump inlet in the float bowl has a fine mesh screen on it. When I took it apart the first time the screen was laying in the bottom of the float bowl. The screen has a rubber grommet that holds it into the carb body and over the years the rubber had dried up and shrunk. The new screen fits tightly......now.

 

I plan on putting the carb back together this morning. There is a small plastic plug with an Oring that pushes into the carb body. If I have a replacement Oring in one of my kits I may even get to try out the carb in the driveway. If I don't have a suitable replacement I'll have to order it. The original Oring has dried up and isn't tight in the hole it goes into.

 

Thanks everyone!!!

 

Your more than welcome brother, hope it all works out and you end up slaying all kinds of fish out there playing with that Yammie boat engine.. Let us know how it comes out..

If it dont work and it was mine,, long before I shelled out 400 bucks for a new one I would probably do a little research on the specs to make sure it would fit and be thinking along this line: https://www.ebay.com/itm/Craftsman-247-88790-24788790-9-Horse-Power-now-Blower-carburetor-carb/223272117076?hash=item33fc0e2354:g:bQYAAOSwH8VeAaEX

 

https://www.ebay.com/itm/Carburetor-Carb-Kit-For-kohler-8hp-on-a-Troy-Bilt-wheel-horse-tiller-Engine/153866645162?hash=item23d32aaeaa:g:SeYAAOSwHfZdPlKg

 

https://www.ebay.com/itm/CARBURETOR-FOR-TROY-BILT-CHIPPER-VAC-47279-47261-65582V-SHREDDER-HORSE-TILLERS/143320921013?hash=item215e97b3b5:g:KpoAAOSwYNVdIDbB

 

When all fails, my favorite saying is: its always something :big-grin-emoticon:

 

Puc

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I put the carb back on the motor and pumped the float bowl full of fuel. I activated the accelerator pump linkage and it did pump fuel. The next day I pulled it out on the driveway and hooked up the cooling water (aka garden hose). This motor has one main lever for throttle and gear shift and a 2nd lever that seems to be a fast idle in neutral lever. I first tried pumping the fast idle lever, but there wasn't enough accelerator pump linkage movement to pump enough gas to start the motor. I switched to the main lever, and pumped it twice. The motor started right up. I had to adjust the idle speed screw, but it runs great and has good throttle response.

 

Now I've got to put the boat in the water and try motors and the live well pump out (I had to change the pump). We have 3 good sized lakes close by but the TVA boat ramps are closed. The county ramps are still open, but very crowded and most don't have docks. One of the lakes about 20 miles away has a nice dock, but I'll have to take a ride and make sure it's open. Maybe next week or the one after the weather looks better.

 

Thanks again everyone for your help. There aren't many things that the members of this site don't know something about.

 

Frank

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I put the carb back on the motor and pumped the float bowl full of fuel. I activated the accelerator pump linkage and it did pump fuel. The next day I pulled it out on the driveway and hooked up the cooling water (aka garden hose). This motor has one main lever for throttle and gear shift and a 2nd lever that seems to be a fast idle in neutral lever. I first tried pumping the fast idle lever, but there wasn't enough accelerator pump linkage movement to pump enough gas to start the motor. I switched to the main lever, and pumped it twice. The motor started right up. I had to adjust the idle speed screw, but it runs great and has good throttle response.

 

Now I've got to put the boat in the water and try motors and the live well pump out (I had to change the pump). We have 3 good sized lakes close by but the TVA boat ramps are closed. The county ramps are still open, but very crowded and most don't have docks. One of the lakes about 20 miles away has a nice dock, but I'll have to take a ride and make sure it's open. Maybe next week or the one after the weather looks better.

 

Thanks again everyone for your help. There aren't many things that the members of this site don't know something about.

 

Frank

 

:thumbsup:OUTSTANDING FRANK!! GOOD JOB BROTHER!!:thumbsup:

 

Thank you for the update,, so many times subjects like this come up, discussions insue and than outcomes just slip away.. You are welcome and THANK YOU for not being one of those:missingtooth:

 

Only other suggestion I might make would be to double/quadrupal check that carb for any leakage.. It only takes a few drops of gas in the bottom of the ship to muster up a big boom boom.. Beyond that,, let er rip my friend!! :thumbsup:

 

Oh yeah,, also dont forget to keep an eye on the water cooling pee stream,, make sure that impellar is functioning.. Sieze the day not the motor.. Oh wait,, its 4 stroke,, probably air cooled.. Oh well, I'll leave this edit intact incase its not

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