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Author Topic: Carburetor help AGAIN B&S 18hp  (Read 4533 times)

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Offline brdmkr

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Carburetor help AGAIN B&S 18hp
« on: September 20, 2010, 09:16:54 am »
It seems I have problems keeping sawdust out of my carb bowl.  Early on, I learned how to take the top off of the carb and clean it out.  This has always worked.  Now it does not seem to help.  Below are the speicifics.  If anyone can offer any ideas, I'd sure appreciate it as I need to be sawing this week and weekend.

1. Mill cranks after sitting for a while.  Then, dies.  Sometimes, you can pull the choke before it dies and it will catch up, but it will eventually die regardless.

2.  I cleaned out the bowl and needle valve and put everything back together.  Fuel is getting from the tank into the bowl.  Fuel lines to the carb are open.

3.  Put carb back togther, same problem as before.  In the past, the cleaning has always worked, but not now.  I feel confident that the mill would crank right now after having set, but it would not run for long.

Is there anything else I should consider?

Thanks much


Mike
Lucas 618  Mahindra 4110, FEL and pallet forks, some cant hooks, and a dose of want-to

Offline pineywoods

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Re: Carburetor help AGAIN B&S 18hp
« Reply #1 on: September 20, 2010, 09:54:53 am »
There's probably still sawdust in the metering jet. You may have to use something like  a tip cleaner to get it out. If that don't work, dis-assemble the carb and soak it in carb cleaner, then blow out the jet with compressed air. The holes a rather small.
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Offline Peder McElroy

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Re: Carburetor help AGAIN B&S 18hp
« Reply #2 on: September 20, 2010, 11:33:38 am »
I also have a lucas 6-18 and am wondering how saw dust gets in the carb,through the air cleaner or what?

Offline Chuck White

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Re: Carburetor help AGAIN B&S 18hp
« Reply #3 on: September 20, 2010, 12:58:49 pm »
I know it's a different brand of engine, but I recently had the same type problem.

I'd start sawing down through a log/cant and get almost to the other end and the engine would die unless I was quick enough to take the blade out of gear.

It would run fine at an idle, but high rpm, it would make a full run.

The culprit was one of the diaphragms in the fuel pump.  It was out of place, with only one side holding.

Put on a pump that goes to a DR® unit and it's running like a top now.

That fine sawdust gets into some really small places.  Sawdust even gets into my gas tank and that vent is probably less than 1/16 inch opening.
~Chuck~
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Offline Slingshot

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Re: Carburetor help AGAIN B&S 18hp
« Reply #4 on: September 20, 2010, 01:51:14 pm »

       I had the same problem with a 15 HP Kohler that Chuck described and finally found a partial
   blockage in the fitting where the gas enters the carbureator. Enough gas would get through to
   fill the bowl and let the engine idle but not enough gas would get through to keep the engine
   running at high speed. Cleaned the little hole out and it ran fine.   



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Offline DanG

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Re: Carburetor help AGAIN B&S 18hp
« Reply #5 on: September 20, 2010, 03:32:09 pm »
I had the same trouble as Slingshot.  The homemade pickup tube was clogging between the tank and fuel filter.  I added a chainsaw filter to the end of the pickup and solved the problem.
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Offline weisyboy

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Re: Carburetor help AGAIN B&S 18hp
« Reply #6 on: September 20, 2010, 04:22:18 pm »
id say the valve on the fload is not opening. conce the fuel in the bowl cets used up there is nothing and it has to slowly fill back up. check the inlet under the  needle.

i had a carby full of [I have typed a profane word that is automatically changed by the forum censored words program I should know better] after i had a broken air filter. but that is after 2000 hours on the machine.

i would consier finding where the problem is in the filter. tht is leting dust in.

Offline Hilltop366

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Re: Carburetor help AGAIN B&S 18hp
« Reply #7 on: September 20, 2010, 06:17:31 pm »
Other things to check is water in the gas and if it has a fuel shut off solenoid that prevents it from back fireing through the muffler. It has a wire that runs to the side or bottom of carb. The wire can come off or the needle valve can get gummed up and stick so it can not open all the way.


Offline Slabs

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Re: Carburetor help AGAIN B&S 18hp
« Reply #8 on: September 20, 2010, 07:40:07 pm »
I didn't see fuel filter mentioned.  18Hp, float carb, fuel pump or not??  Regardless, operation in a dusty(including sawdust) environment, a fuel filter is a must.  The little "inline" units work well and can be installed in a flex line somewhere though I'm a strong advocate  for sediment bowls.  Change or clean them ocasionally.

Good luck
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Offline sawguy21

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Re: Carburetor help AGAIN B&S 18hp
« Reply #9 on: September 20, 2010, 10:56:16 pm »
Check the seal between the carb and air filter base and around the filter. Fine sawdust could sneak in and be drawn through the bowl vent which is next to the choke butterfly.
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Offline brdmkr

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Re: Carburetor help AGAIN B&S 18hp
« Reply #10 on: September 20, 2010, 11:42:21 pm »
Check the seal between the carb and air filter base and around the filter. Fine sawdust could sneak in and be drawn through the bowl vent which is next to the choke butterfly.

That is how the dust got in the bowl.  The nut that held the filter vibrated loose and dust made its way stright into the carb.

Today, I thought I would try to run it again.  Maybe the results were better maybe not. 

Today, the mill would run but it surges.  Runs good a second, acts like it is running out of gas and then 'catches up'.  It ran this way for 10 minutes or so, before I shut it down.  If you hold the choke out slightly, it runs smooth.  However, the choke will not stay in this position without being held there.  If you get it in the sweetspot and take your hand off, it goes full choke and will shut itself down. 

On the offbeat chance it would help, I put a hefty dose of seafoam in the tank (It already had the recommended amount).

Fuel flow from tank through in-line filter to bowl is fine.  The bowl fills up fine when the float is down.  All of that is clean.

Do these new symptoms help?
Lucas 618  Mahindra 4110, FEL and pallet forks, some cant hooks, and a dose of want-to

Offline Chico

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Re: Carburetor help AGAIN B&S 18hp
« Reply #11 on: September 23, 2010, 03:02:13 pm »
You using outerwear on your filter ? I used to take pantyhose and tie them around the whole assbly if I couldn't find anything else It helps but an outwear and even and oil bath filter may help tho I'm partial to dry filters but sometimes you have to experiment jmo
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Offline mad murdock

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Re: Carburetor help AGAIN B&S 18hp
« Reply #12 on: September 23, 2010, 03:08:42 pm »
That is a DanG fine idea you got there!! I second DanG's idea of putting a saw inlet filter on the pickup tube in the tank.  Sawdust is real fine, and can get into the tank through the tank vent, settle to the bottom and get sucked up the intake tube causing issues like they experienced for sure.
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Offline arnold

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Re: Carburetor help AGAIN B&S 18hp
« Reply #13 on: September 25, 2010, 06:45:36 am »
When I was the agent for Lucas in New Zealand we came across similar problems on the 18 hp and found that when the air filter blocked it created a vacuum and the engine is looking for more air.  On the carb. there was vent or breather which would allow sawdust to get dragged into the needle valve and bowl. We ended up putting a rubber hose on that breather and drilled a hole into the inside of the filter base and that fixed the problem. I am not sure if the manufacturer added this on later engines or not.
I recall the carb make was Nikki of japan. they are used on other makes of engines so the problem was widespread. 

Offline Magicman

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Re: Carburetor help AGAIN B&S 18hp
« Reply #14 on: September 25, 2010, 09:20:39 am »
Chico, you have been gone for over 5 months ???  Welcome back.   :)
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Offline Meadows Miller

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Re: Carburetor help AGAIN B&S 18hp
« Reply #15 on: September 26, 2010, 06:28:45 am »


HEY CHICO Nice To Have You Back Mate  :o :) ???  ;) :D :D ;D ;D ;D 8) 8) 8)
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Offline sigidi

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Re: Carburetor help AGAIN B&S 18hp
« Reply #16 on: September 26, 2010, 07:43:40 am »
My first Lucas (Larry) was the 6-18...

First thing, I used to do in this situation is dump the fuel tank, take at it with compressed air and 'dry' it out,
then open up the carby and clean her out too, compressed air again to finish,
lastly air filter and foam pre-cleaner off, blow filter out from the inside, then wash the foam pre-cleaner and oil it before going back on.

Once everything is back together it should be sweet again, but to stop that wing nut or thumb nut on top of the filter coming undone again, I locked a second on top of it.

Also another thing I used to do before pulling everything apart, if I suspected a bit of crud in the carby, get up to full revs, pull the choke out until it has all but stalled, then dump the choke back in quick, when she fires back up again, it tends to pull a heap of crud through, try doin this a couple of times to save having to pull everything apart.
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Offline Chico

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Re: Carburetor help AGAIN B&S 18hp
« Reply #17 on: September 27, 2010, 12:36:23 am »
Thanks Ya'll have had a lot going on
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Offline brdmkr

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Re: Carburetor help AGAIN B&S 18hp
« Reply #18 on: September 28, 2010, 12:06:46 pm »
Thought I'd provide an update.

I cleaned all the jets, needle valve, and bowl.  The surging went away, but now it runs good for a few seconds, runs out of gas and dies.  Let it set for few seconds, and it will fire right up.  I am sure that I have a flow problem from the tank to the bowl.  I will clean the tank and lines this evening and put on a new filter.  If that doesn't do it, I suppose I'll need a new needle, but the existing needle looks fine.
Lucas 618  Mahindra 4110, FEL and pallet forks, some cant hooks, and a dose of want-to

Offline paul case

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Re: Carburetor help AGAIN B&S 18hp
« Reply #19 on: September 28, 2010, 01:34:15 pm »
i bet it wont need any parts changed like the needle. its the illustrious carb crud. it only shows up when it is all bolted together. check the flow from the tank and if that aint it it must be more stuff plugging somethin up in the carb. break out the wrenches again.
aint that just the way it goes?  pc
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pc