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Fuel streaming from the air box!!!

  • Thread starter Thread starter Bruin
  • Start date Start date
B

Bruin

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I have tried the search feature but haven't found my problem anywhere. I ran my 650 almost to the point where I needed to switch to reserve but gassed up just before I needed to move the lever. When I left the gas station I noticed the bike would bog down until after a second or two at full throttle and every time I let off the throttle it would do it again. I figured I had a stuck float again so I tapped on the bowls and it stopped leaking fuel and idled smoothly again. This problem happened before when I switched to reserve but was cured by tapping on the carb bowls. This time I wasn't so lucky. I got the bike back home and started looking it over to see exactly what was going on. The fuel is pi**ing out of the line that comes from the air box and ends in front of the rear tire. I found a line just sitting on top of the engine too. It looks like it attaches to the gas tank at a point behind the petcock. There is a thing hanging down that a line would attach to and the bend of the hose sure looks like it should go there. The thing is, I can't see anything that the other end would attach to. Is this a vacum line or something? It is about 8 inches long with a bend at one end. Is this line the problem or are my floats still stuck? Any ideas? Thanks in advance for any help.
 
I would go with the floats being stuck... I have had it where gas would pour out the vent tubes while they are 3 to 4 inches higher then the carbs.

The only other vents could be if your tank happen to have been vented by a hose from the bottom, but if you over filled your tank it would leak there, however it wouldn't have a dramatic effect on the operation of the bike.

I would check the floats
 
You should have 2 float bowl vent hoses that are open to the air. 1 hose to vent the gas gauge that is open to the air. And 1 smaller vac hose from the #2 carb to the petcock. It does sound like a stuck float, have you rebuilt your carbs? Good luck
 
Maybe it was some dirt in fuel tank (after running fuel low to nearly reserve level) that got into needle/seat area and now not shutting fuel flow off, causing overflow.
 
lucabond said:
You should have 2 float bowl vent hoses that are open to the air. 1 hose to vent the gas gauge that is open to the air. And 1 smaller vac hose from the #2 carb to the petcock. It does sound like a stuck float, have you rebuilt your carbs? Good luck
Click to expand...
Well, close. That hose does not actually vent the gauge, or even the sending unit. Since the sending unit bolts to the inside surface of the tank, and there is a gasket involved, there is always the possibility that the gasket can fail. Since that is directly over the engine, there is a shield around the bottom of the sending unit flange to catch any gas that leaks. The attached hose merely directs any gas that drips from there away from the engine.

.
 
Steve said:
Well, close. That hose does not actually vent the gauge, or even the sending unit. Since the sending unit bolts to the inside surface of the tank, and there is a gasket involved, there is always the possibility that the gasket can fail. Since that is directly over the engine, there is a shield around the bottom of the sending unit flange to catch any gas that leaks. The attached hose merely directs any gas that drips from there away from the engine.

.
Click to expand...

No, it's definitely running out of the hose that comes from the airbox. I'm pretty sure that sticky floats are the gremlin here. I was at WOT most of the trip trying to stay with my buddy's CBR 1000. What a tard huh, trying to keep up with him on a 650 L. Sounds like it's time to clean some carbs. Looks like I will have plenty of work to do on it this winter. It needs a new steering head bearing and some new engine gaskets. Gonna check the valve shims while I'm in there too, maybe swap the damn L bars for some daytonas.
 
The petcock works off the vacuum from your engine. Engine runs, vacuum occurs, diaphragm in the petcock opens, fuel flows to the carbs. Stop engine, diaphragm closes, fuel stops.

If the petcock is in the PRI positions the fuel just flows to the bowls - no diaphragm needed. If it's in the ON or RES position, diaphragm needed.

In your case it sounds like your vacuum line from the carb to the petcock is off. It also sounds like the diaprhagm is shot leaving the petcock open OR it's in the PRI position. Fuel runs into carbs, overflows the bowls, runs into airbox, drips out breather hose.

Reattach the vacuum line to the petcock, put lever in ON position. Try that first before tearing into your carbs.

Seen it, done it, been there.
 
Buster-boy said:
The petcock works off the vacuum from your engine. Engine runs, vacuum occurs, diaphragm in the petcock opens, fuel flows to the carbs. Stop engine, diaphragm closes, fuel stops.

If the petcock is in the PRI positions the fuel just flows to the bowls - no diaphragm needed. If it's in the ON or RES position, diaphragm needed.

In your case it sounds like your vacuum line from the carb to the petcock is off. It also sounds like the diaprhagm is shot leaving the petcock open OR it's in the PRI position. Fuel runs into carbs, overflows the bowls, runs into airbox, drips out breather hose.

Reattach the vacuum line to the petcock, put lever in ON position. Try that first before tearing into your carbs.

Seen it, done it, been there.
Click to expand...

If the float bowl gaskets don't leak, floats are set right, the needles seat good, and the o-rings around the seats are good, it doesn't matter if the fuel is on, off, or funneled in bring your beer helmet, the float bowls should never fill past the set mark causing fuel to pour out, drip ot anything else.

Unless you have a tank 30 feet up in the air feeding the carbs with a 1/2" fuel line, fuel should never push/leak past the needles or O-rings around the seats.
 
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