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localdj77

Crazy pressure build up and flooding....see story

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localdj77

Ok so you guys have been great and I'm slowly getting the bugs worked out of the beast......heres the latest.....

 

I started the tractor and got it warm in prep for final carb tuning per previous threads you have helped on.  It ran like a champ and I started to tinker with the low idle screw.  All of a sudden it died and I was sure that I had adjusted it too far out so started back where it was and tried to start the engine again.  It wouldn't fire for anything.  Long story short I never re-opened the pit cock from the last time I worked on it.  When I did that it had built up so much vacuum that it quickly filled the fuel filter completely and also filled the carb so much it puked fuel out of the carb.....all without the engine running!  I never had this problem before and even had it running for over 30 minutes last week with zero issues.  I finally got it started and it ran for nearly 5 minutes with the gas shut off.  Problem is that now everytime I open the pick cock it floods the whole darn thing in a matter of seconds....

 

Should it be building so much vacuum???  Should I just bleed the pressure but removing the line and start over?  Did I damage the float or something?  I'm bummed because I was planning on using it tonight!!!

 

Help!  lol

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ford2go

Hi,

I'm far from an expert, but I'd guess that your needle valve isn't seating or your float is sticking. Cranking the engine will run the fuel pump and if the needle valve doesn't close the bowl will overfill.

 

Simplest thing would probably be a kit that covers that area. Should include gaskets, a float and the valve. This forum seems to have manuals available  -- some of which probably cover your carburetor. If not, Kohler engine manual pdfs are floating around the web. (I assume that it's a Kohler) .  The kit may also include instructions, but it's good to be sure. You have to bend pieces of the float to locate it at the correct height etc.

 

If I can do it with two  all thumb left hands you certainly can :).

 

Doubt if you hurt anything.

 

hj

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rmaynard

What engine are we taking about, and what model tractor? The above info on the float sounds like the most likely answer.

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localdj77

Thanks guys.....I was assuming that but I haven't torn into it yet.  312-8 Kohler Magnum........still thinking the same thing?  Sorry I didn't mention the model at first.

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WH nut

If you had a vacuum and heard hissing when you open the fuel cap you have a vent plugged in the cap

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localdj77

No basically it was building pressure because I had the pit cock closed.....as soon as I open that it bleeds the pressure but thats when the flodding happens.  I'm fighting an uphill battle because I'll run the engine with the cock closed to burn the gas in the bowl which builds pressure in the line so when I open the cock it floods it again.  I know that if I cut the line to bleed the pressure it will get me back to square one but I'm assuming that regardless it should NOT be overflowing in the carb.  Could it do so because of the rush of gas??? 

 

I guess maybe I will bleed the pressure and start over.  If it still floods then I need to look at the float and valve......right???

Edited by localdj77

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WH nut

Closing the pet cock should not build pressure. Why are you closing it anyway. Is it leaking if left open?

Edited by WH nut

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localdj77

It hasn't leaked up to this point.  To be clear....if the pet cock is closed and the engine runs or is cranks it builds vacuum.... 

 

I went home at lunch and messed with it some more.  I slit the line, it released the vacuum then I cut the line and reinstalled on filter.  Opened the pet cock and it fired right up.   Once I got it off choke I got it to partial throttle and it would misfire every couple seconds.  I am not educated on carbs so I don't know the symptoms but there wasn't any noticeable black smoke and it I pulled the choke a bit it would start to dye.  When I ran it down to idle it died so I screwed the low screw in all the way and backed it out 2.5 turns.  It will now idle extremely low around 700 rpm for a few seconds and die.  It will start back up once I raise the throttle.  FYI if you havn't seen all of my threads.....I cleaned the carb and all was good....i was going to tune the carb and thats when I left the pet closed which when opened it caused the puking of gas.   

 

So, should I attempt to tune as is or should I still pull the bowl off the check the float valve?  It didn't leak during the 5 min or so while it was running so I think that problem might be fixed?

 

If I should tune as is....which direction should raise my idle?

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WH nut

Closing the pet cock should have no affect What little vacuum that the pump might pull will not cause the carb to flood

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localdj77

I sure wouldn't think so either but the vacuum came from somewhere.  It created such vacuum that I had to slit the hose.  I tried and tried to remove the line from the filter and it just wasn't possible!  It had only been on for a couple days so it not like it needed extra attention to be removed.  It is a new pump.....mech pump.....i ditched the electric pump in favor of the mech.

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WH nut

I think a new needle and seat is what you need to be looking at. I think the fact you cant get the line off is creating tunnel vision.

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leeave96

IMHO - if you are pulling a vacuum, that tells me your fuel pump is working great! So from your tank to the pump you are OK. If the engine floods once the fuel is flowing from the fuel pump, then ypu've got a bad float, needle/seat or both. This will let the gas flow in volumes greater than the engine can digest as the fuel pump is doing it's thing and to much gas is getting into the carb.

Revisit your fuel bowl, float and needle/seat and you might have a fix.

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localdj77

I will do that next.  I was reading the manual and it says to see "carburator chart" but I don't see it in the manual.  Is it a seperate document?  I'd like to know how to adjust!  Even if the valve/seat is the problem I still need to do the initial tune afterwards. 

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19richie66

Your float could have a pinhole in it which would not let it "float". This would not shut the fuel off when the bowl gets full.

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localdj77

Ok so I dropped the bowl and found a little bit of a film but all in all everything looked could considering I cleaned everything up a  couple months ago.  I played with the idle a bit and couldn't get it locked down.  I also ran it up to full throttle to get a good RPM number.  It revs all the way to 4k!  I quickly backed it down because I figured it was way too high.  I decided to just regulate the throttle manually to just above idle and maybe 80% throttle to get the lawn mowed.  All went well!  At 3500rpm approx it runs like a champ and at about 10% throttle it purrs......at say 50% it still seems to miss.  Not sure what that was about but at least I was able to use it.  I figured until I have more time to tinker it was worth just using it and just being careful of the revs. 

 

One thing I did notice what that it didn't seem to cut well......but the blades are to dull they are more like rotating steel stock than blades....lol....thats next.


Forgot to mention....never overflowed last night......check the cloat and valve and all seemed fine.  All I can think it that when I released the pressure after cranking so long with the pet cock closed.....the carb just couldn't handle the rush of fuel?!?!?!  All I know is it seem fine now.  Where could I find info to keep it from over revving?

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cleat

My K341 in my Ford is sort of the same. Smooth at high RPM, Normal vibration at idle but steady. Slight intermittent miss at part throttle.

 

Been like this for years. Carb rebuild has no effect. Throttle shaft and bushings replaced as well.

 

Cleat

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Molon_Labe

If you are turning 4K with that Kohler you need to adjust the governor. This link runs you through the procedure, it's simple, just make sure to follow it to the letter.

 

http://cubfaq.com/govadjust.html

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localdj77

great.....thanks!  I will check things out!

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