Carburetor Flooding CV carb

S

STS 95

Club Member
Hi, 1995 FXSTS with a CV carb. Issue one, gravity fed petcock fuel pissing out the carb after a winter lay up. Checked the float level, checked the cut off valve no sign of wear or sticking and all working when you blow air through the carb fuel inlet. Air is cut off as you move the float. Still pisses out fuel. New CV carb with vacume fed petcock all connected, fuel flowing when the engine is cranked and the fuel still pisses out of the carb. Float bowl removed, engine cranked, fuel flowing, raise the float gently until petrol stops flowing, its all working as it should. Rebuild and try again, fuel still pissing out. Question, is the petrol tank pressurising ? How do I check that the fuell filler caps are vented ?
 
Place cap in mouth and blow to check cap take float assy out and place in water check for bubbles caused by perforations due to fuel sounds like float fills up staying open……
 
Thanks for the reply, right hand fuel tank has a venting system that responds to sucking and blowing, so that means the tanks are not pressurised. Both the old float and the new float are perfectly air tight, no holes, no bubbles and no fuel rattling around inside.
 
Just mulling this one over when you replace the needle on the float its wire carrier is it centered on the tang if twisted to one side it will jam and flood also is the float going back right way up had one that had been put in upside down and tang bent to fit
there is a float level measurement in the workshop manual which involves leaning the carb at an angle to set the tang on the bench to cure flooding hope this is of some use
 
First thing I did was check the how too in the manual and on U Tube videos. I created a 15 degree ramp and set the float to 11 mm as per instructions. I tested the response by blowing air into the fuel inlet and then tilting the carb to make the float rise. The air flow stops, therefore the cut of valve is working. Then again the fecking thing is not working when fuel is around it. What am I missing ?
 
It's worth checking the float for any rough edges. Sometimes the seams are rough and this can cause the float to stick when in situ.
 
Thanks for the help, the float is as smooth as a babys --- and the needle valve has been checked for any rough edges. The hole that it sits in has been cleaned and I can get it to spin when I blow air into it. The pin that holds the float has been checked, polished and re installed. It still pisses fuel out.
 
i think you need another pair of eyes to look at it ,,

some thing simple that your not seeing ,,,we've all been there

john
 
Finally sorted out the flooding CV carb, threw it in the bin. Seriously, paid £215 for a replacement CV carb (made in Tiawan and brought in from USA) absolute shite do not buy one of these carbs. Refunded so all is good. Bought a HSR 42 Mikini (made in Mexico ) fuel flooded out of it even worse than CV, obviously something missing inside. New replacement arrived yesterday and installed it a couple of hours ago, perfect, did not even have to adjust the tickover. I have since been told that the O ring and the diaphram inside the accelarator pump could be the source of the flooding problem in the old CV carb, I might repair it and sell it.LOL
 
STS 95 said:
I have since been told that the O ring and the diaphram inside the accelarator pump could be the source of the flooding problem in the old CV carb, I might repair it and sell it.LOL
Click to expand...

i had a similar problem with a butterfly keihin (I know....). Same scenario. Rebuilt using brand new valve, gaskets and O rings. Turns out - the ball check valve in accelerator pump body wasn't free (no rattle) so cannibalised another and replaced; and, to my disgrace, I'd lost one of the tiny O rings sealing fuel channel up into float bowl....

Anyway, seems ok now. So your thought about accelerator pump seal may well be correct.
 
check the black plastic elbow that the petrol pipe goes on to. They are prone to breaking. I had one leak a few years ago due to a small crack. you can get a brass replacement from Harley or CCI, Zodiac etc. the petrol will run down the outside of the float bowl which makes it look like it is leaking.
If you lay the bike up for the winter drain the tank, and it sounds like your petrol tap isn't turning off completely.
 
Last edited:
STS 95 said:
Hi, 1995 FXSTS with a CV carb. Issue one, gravity fed petcock fuel pissing out the carb after a winter lay up. Checked the float level, checked the cut off valve no sign of wear or sticking and all working when you blow air through the carb fuel inlet. Air is cut off as you move the float. Still pisses out fuel. New CV carb with vacume fed petcock all connected, fuel flowing when the engine is cranked and the fuel still pisses out of the carb. Float bowl removed, engine cranked, fuel flowing, raise the float gently until petrol stops flowing, its all working as it should. Rebuild and try again, fuel still pissing out. Question, is the petrol tank pressurising ? How do I check that the fuell filler caps are vented ?
Click to expand...
Same thing has just happened to me, first time started in a couple of months... 98 FXSTS. Will come back to this information no doubt!
 
You must log in or register to reply here.
Back
Top