Author Topic: engine wants to die while idling? (Read 2100 times)

sawman · « **on:** November 24, 2009, 07:25:41 pm »

Just got off the phone with dad and he says that when he releases the clutch on our 95 lt40, when the engine goes to idle it just dies.
When he restarts it he says it acts like it is flooded.
He has checked and changed the spark plugs,& wires, took carburetor apart and check and cleaned it.
Nothing he has done so far has helped.
He says he has fresh gas in it, and that it has been doing this the last few times he has sawn.
We have the 24 HP Onan on this mill.
Anyone have suggestions on where to look next?
Thank you in advance for any ideas or suggestions.

fishpharmer · « **Reply #1 on:** November 24, 2009, 08:11:02 pm »

A dirty air filter can choke it down. You didn't mention that.

coastlogger · « **Reply #2 on:** November 24, 2009, 08:39:15 pm »

sounds like the float needle is letting too much gas in,not a prob when engine drawing lots of fuel, engine floods and dies when idling. Could prove/disprove this by pinching off fuel line to carb with vice grips, see what reaction of engine is.If it is this, disassemble and clean carb, checkto make sure float is not "sunk".
clgr

Chuck White · « **Reply #3 on:** November 24, 2009, 08:42:10 pm »

I have the same problem with my LT40!

I think I have it narrowed down to the fuel pump or the governor!

There are 1153 hours on my mill!

I have a tech. coming in after hunting season to take a look and get this thing cleared up for Spring sawing season!

Keep us posted on what you find with your engine!

John_Haylow · « **Reply #4 on:** November 24, 2009, 08:46:28 pm »

Have you checked the o rings on your fuel tank quick connects?
John

Slingshot · « **Reply #5 on:** November 24, 2009, 08:52:10 pm »

Did you try turning the idle screw, (you should have one), to increase the idle speed just a little?

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firecord · « **Reply #6 on:** November 24, 2009, 08:52:53 pm »

Sounds likethe low speed jet is cloged. Usualy it is in the center tube protruding into the bowl. Take it out and clean it with a cutting torch cleaner or blow high pressure air through it. the slightest obstruction will cause it to die on idle.

sawman · « **Reply #7 on:** November 24, 2009, 09:29:49 pm »

He tried adjusting idle screw, no help
Air cleaner has been checked and cleaned
The search continues,
Keep the ideas coming
Thanks

He will double check carb tomorrow and try pinching fuel line off and see
what happens.

Posted on: Today at 07:42:10 PM Posted by: Chuck White
Keep us posted on what you find with your engine!

Hey Chuck, keep us posted as well.

paul case · « **Reply #8 on:** November 24, 2009, 10:37:47 pm »

i have some of that same type of problem with my honda 20 on my e-z boardwalk mill. it has a way to speed up the idle a little bit on the throttle control. it still revs up and down a bit when running at a faster idle. ive never had it act like it had flooded any. the gas we buy today is suspect to me. sure dont burn as good as the stuff we could get 10 years ago.i know you have checked this but sorry gas sure comes to mind with your symtoms. pc

bandmiller2 · « **Reply #9 on:** November 25, 2009, 07:15:12 am »

This time of the year it could be carb. iceing,and it dosen't have to be below freezing.Frank C.

solidwoods · « **Reply #10 on:** November 25, 2009, 10:01:06 am »

Quote from: firecord on November 24, 2009, 08:52:53 pm

Sounds likethe low speed jet is cloged. Usualy it is in the center tube protruding into the bowl. Take it out and clean it with a cutting torch cleaner or blow high pressure air through it. the slightest obstruction will cause it to die on idle.

Ditto.
Also the way to check if an engine is flooded is smell the exhaust as you crank the engine.
jim

Chuck White · « **Reply #11 on:** November 25, 2009, 10:20:41 am »

Quote from: John_Haylow on November 24, 2009, 08:46:28 pm

Have you checked the o rings on your fuel tank quick connects?
John

I have eliminated an O-ring leak by removing the quick disconnect and sticking the hose directly into the the gas tank!

- - - - - - - - - - - - - - -

My engine doesn't flood out, because I have to choke it in order to restart it!

- - - - - - - - - - - - - - -

Here's the link to my post back in October with the same problem!

http://www.forestryforum.com/board/index.php/topic,39793.0.html

It ran good for a while and then started acting up again!

jdtuttle · « **Reply #12 on:** November 26, 2009, 08:44:13 am »

That engine is known for carbon build-up on the heads. i just changed mine out to the kohler 25hp. They make several products you can use to help remove the carbon.
good luck

Burlkraft · « **Reply #13 on:** November 26, 2009, 08:52:01 am »

I had the same problem with mine.

I quit using gas with ethanol in it and that engine runs better than it has in a long time.

MartyParsons · « **Reply #14 on:** November 26, 2009, 08:53:52 am »

We have ahd a # of these issues in the last couple of weeks. All have been carb issues. It only takes one drop of water. I remove the top of the Carb pull out the main jet, pull out the brass jet clean and dry reassemble. Remove the fuel pump clean out water and dirt. Remove the fuel tank clean and dry. Purge out the fuel line. There is also a governor spring that sometimes breakes. This may not be your problem but that is where I would start. If you did not clean the fuel pump before starting remove the carb top again there may be water back in there. ?
Hope this helps!
Marty
I think the ethanol may also be a big issue.

solidwoods · « **Reply #15 on:** November 26, 2009, 02:12:19 pm »

Definitely stay away form gasoline with alcohol.
Unleaded gas without alcohol will absorb water from the air and water in the bottom of the tank. More when it is warm, and it will shead water when cooled.

But alcohol absorbs water even easier than gas.
Gas with alcohol can have a higher moisture content than straight gas.
When the engine cools down, some of the water falls out of the gas and settles in the bottom of the carb. The carb bowl will corrode and let loose of small flakes of metal headed for the fuel path.
Or if your lucky fuel fungus. Yep fungus can live in fuel just ask a boater.

If you have a vibration type fuel pump:
Set a gas tank up that is above the elevation of the carb.
This makes it easier for the pump to pull gas.
Run the engine long enough to fill the fuel path then try idle.
Got idle = weak pump or restricted flow.

Most vibe. pumps have a weep hole that is on the non fuel side of the rubber diaphragm (that does the shaking-n-baking) , so if the diaphragm is leaking you'll see fuel seeping from the weep hole. (also done on auto/some water pumps).

Fuel filter good also installed the right direction?

Polly · « **Reply #16 on:** November 26, 2009, 07:51:34 pm »

i had simelar problems with my onan ,until i started using 97 octane gas , ialso add sta bil that i get at wal mart shebam after a couple tank fulls engine problems were solved , sthl chain saw manual says use mid grade gas also ,

backwoods sawyer · « **Reply #17 on:** November 28, 2009, 11:24:46 am »

I believe everyone is on the right track with it being fuel related. Over the last couple of weeks, I have had to pull apart several carburetors for others do to moisture in the fuel. I use a big can of carburetor cleaner and use it liberally, as it has enough pressure to clean out the jets and flush all that grime out. If you are done milling for a period of time, drain the fuel system and it will save you head aches when you go to use it again.

customsawyer · « **Reply #18 on:** November 28, 2009, 11:30:11 am »

I don't think that the gas we get these days will even last two weeks.

tomsteve · « **Reply #19 on:** November 28, 2009, 11:47:29 am »

i'm not a carb expert, but sounds like dirt in the carb to me. maybe even a little gumming on the needles. i like to run some seafoam in all of my gas powered stuff as it keeps the fuel systems and combustion chambers pretty clean.

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Author Topic: engine wants to die while idling? (Read 2100 times)