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Post by crazedfox on Dec 22, 2013 10:07:25 GMT -6
Ok, _this is the 2'nd carb i've put on this scooter (peace sport, renegade, 50cc QMB139.) The last carb was a throw away type. (No air/fuel screw, tamper-proof fuel bowl screws.) Now the new carb ran fine, I just needed to fine tune it to my weight, & scooter's eng. Changed out the pilot jet, reused the main jet fro old carb, adjusted the air/fuel screw, & adjusted the accelerator diaphragm needle a few times. (accelerator diaphragm needle; the can with 2-screws on top.) (& yes I know to be careful not to pinch or damage the diaphragm.) I believe it started puking fuel after the accelerator diaphragm needle was adjusted. Not real sure of when, but is my best guess. Now this is the second carb that has the same problem, what the hay is going on? Carb looks like this one -  _ |
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Post by crazedfox on Dec 22, 2013 14:46:59 GMT -6
Any chance the float needle may have been over
powered by the gravity of fuel coming in?
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Post by JR on Dec 22, 2013 19:06:38 GMT -6
When you say puking fuel are you saying it's coming out the side over flow hose? If so then the needle is hung, or float is badly adjusted.
Please tell me what you mean by puking fuel?
JR
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Post by alleyoop on Dec 22, 2013 19:07:21 GMT -6
What do you mean pucking fuel? Are you saying fuel is coming out of the overflow VENT tube near the top of the carb??
What size Carb 18,19,20 mm etc.. And what size Pilot Jet and Main Jet are you putting in the carb. And why are you upjetting and messing with the needle? Is this a stock 139QMB or have you got a BBK on it and or Free Flow Filter and or free flow exhaust.
Explain what it is doing bogging, making Popping Sounds when on Throttle or Decel, Braat Sounds Backfiring etc..
Alleyoop
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Post by crazedfox on Dec 24, 2013 20:04:11 GMT -6
18mm carb.
Fuel is comming out the intake bell.
By ether the main jet or pilot jet venturi openings I believe.
Tried to stop the overflow of fuel by JB welding the bumper on a float needle,
then tried an adjustment on float to lower fuel level.
Both ajustments failed.
(No dirt, or foreign object found ether.)
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The main jet was too small & pilot was too big.
The acceleration diaphragm needle was adjusted to stop stumbling on acceleration.
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When left alone long enough,
it will even leak past the vacuum pecock valve.
I tested the valve & it dose function properly.
But, I still suspect it's broke.
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Side note;
I have upsized the fuel line from 1/4 to 3/16th of an inch.
Would this have any correlation to my problem?
Or is it even relevant?
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Post by alleyoop on Dec 24, 2013 20:30:49 GMT -6
Got to tell you, you did not have to do anything but adjust the Fuel Ratio Mixture on the carb. I know carbs like the back of my hand and you have a stock 139QMB motor all stock and a 18mm is plenty of fuel for that motor.
I do not understand what you JB WELDED but you should not have done that.
IF the VACUUM LINE from the manifold intake going to the PETCOCK has gas YOU NEED to replace the PETCOCK, it is leaking gas through the Vacuum line. That alone will throw off all and any adjustments you can make on a carb. You are trying to compensate for the extra fuel it is sucking in through the VACUUM line.
What size JETS did you put in?
Also from what you say gas is coming out of the AIR FILTER SIDE is that correct? DO YOU have the AIR BOX Tubing connected or have you got that off? If gas is pouring out that means the FLOAT is not shutting off the fuel inlet. DID you mess with that at all?
Sorry to say but you have messed up your new carb pretty good.
My Advice is get another new carb and DO NOT TOUCH it and come on here and I will help you set it up right for your motor.
Alleyoop
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Post by crazedfox on Dec 27, 2013 13:44:13 GMT -6
Figured I messed it up good.
Yes, the fuel is coming from the air filter side.
But it isn't getting fuel from the petcock valve, the vac line has always been dry.
Still, does having a larger fuel line cause this overflow to occur over time?
(I up-sized the line from 1/4" to 3/16".)
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Post by alleyoop on Dec 27, 2013 13:57:34 GMT -6
3/16 is smaller diameter than a 1/4, but that really does not matter only so much gas can come into the Carb Bowl and the Float should rise and push the valve up into the fuel inlet and not allow anymore fuel to flow in. Did you happen to take the Bowl off and mess with the Float or settings? Alleyoop  |
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Post by crazedfox on Dec 30, 2013 3:59:32 GMT -6
Only worked on the float after it started over flowing the carb.
Oh sorry about the fuel line size,
I meant 5/16"
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Post by alleyoop on Dec 30, 2013 12:05:19 GMT -6
Is it FIXED?
Alleyoop
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Post by crazedfox on Dec 31, 2013 1:11:00 GMT -6
Not yet.
Dealing with catch-22.
No ride-No cash
no cash-no parts
No parts-No ride
& that's the catch-22 I'm dealing with.
I'm disabled & have limited income.
-Mental/Social disorder coupled with other memory/coordination issues.-
Took me around a year just to get the funds to purchase this darn scooter.
The only reason I got it was, it was new.
& half the price of name brand scoots.
I didn't want to be having to deal with unknowns,
or someone's lack of maintenance that older rides come with.
& used dealers where too far to get to.
Heck it took me a week just to get a ride to purchase this scoot.
Disability income really sucks.
Ugh...
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Post by alleyoop on Dec 31, 2013 1:17:33 GMT -6
I mean did you fix the OVERFLOW, that should have fixed the flooding of the carb if you adjusted the Float correctly and you did say pushing gently on the float DID stop the air you were blowing in.
Alleyoop
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Post by crazedfox on Dec 31, 2013 22:24:00 GMT -6
Tried to adjust the float, after it started to overflow. .
But no matter the adjustments,
it still overflowed.
That's why I tried to see if this has happed to anybody else.
I know I need a new carb. because this one is trashed.
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Post by alleyoop on Dec 31, 2013 22:39:18 GMT -6
Your not doing something right that is all, these carbs are simple and easy to fix. Your just not doing it right. If you did it like in the PICTURE on how to adjust it AND YOU BLEW INTO the fuel inlet and it stopped the air, it will stop the fuel from coming in when the float gets to that level. Or the rubber tip is damaged on the valve and it will no longer seal.
If you cannot fix the flooding then you will need to get a new carb.
Alleyoop
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Post by crazedfox on Jan 1, 2014 21:30:24 GMT -6
Figured on that, or rebuilding it.
But with rebuild kits costing almost as
much as the carb's initial purchase price.
What's the point rebuilding it?
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*Sigh*
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If I don't rebuild it, I'll see about
finding a high quality one.
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It would be nice if I could afford the EFI kit.
No carb tuning, just a little time for the system to learn.
& the bonus is, infinite tuning capabilities.
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..BAD TO THE BONE..