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Not getting gas into carbs.

8K views 17 replies 6 participants last post by  gymkhanaGuy 
#1 ·
Read and searched, still can't figure this out.

Bike ran prior but would randomly stall and die on me. Happened twice in a period of 5 days.
Decided to clean carbs.

Removed and cleaned. Nothing is ripped, nothing is sticking, carbs were relatively clean when I opened them up.
Assembled everything back. Now the bike won't start.

Checked petcock, fuel is flowing well when I apply vacuum by attaching a hose to the vacuum nipple on the petcock and sucking on it.

Removed tanks, filled carbs with fuel via the fuel hose that attaches to the tank.
Bike starts right up and runs.
Filled the hose back up again, attached the tank.
Bike starts up, runs, but then dies as if out of gas.

Opened drain bolts on the carb float bowls, no fuel is coming out.

Looks to be that the carbs are not generating vacuum for the fuel to start flowing.

Any ideas?
 
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#6 · (Edited)
Sounds like the petcock is opening properly when vacuum is applied, but once it's hooked-up to the carb the vacuum is not sufficient - so gas flow stops.

Check the hose for cracks or cuts and make sure it's attached to the correct port.

With the engine running you should be able to unplug the hose from the petcock and feel vacuum by covering the end with your finger.

EDIT: If that's good, you have a blockage.
 
#7 ·
I'd suggest to discard the inline filter, revert back to a stock continuous length 8 3/4" fuel line....correctly routed, just like the factory intended.

See how that works out. Going forward...

at a later time, provided your fuel tank is not filled with rust, particulates, dead birds, rocks or stones...go with the proven rail filter. All thats needed in an otherwise functional EX500 fuel system, no fuel line cutting, hacking or routeing issues.

http://www.ex-500.com/50-carburetors/23180-easy-fuel-filter-alternative-yes.html
 
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#8 ·
I'll try without the filter, but I have a question about this thing.


One of the vacuum tubes goes into that thinner nipple. I removed the hoses from it and took a look inside, it looks to be pretty rotten and corroded.

Since one of the Carb's vacuum tubes is connected to it, does this valve provide vacuum?
Could it be damaged and not sealing correctly?
 
#9 ·
#10 ·
So the kit includes the Carb Vacuum Cap, which I'm assuming goes on the Carb to eliminate the hose going from it to the PAIR valve.
It seems to me that the PAIR valve must hold vacuum, since carb vacuum is connected to it.
So if I have a defective PAIR valve, that does not hold vacuum, that would be the issue I'm facing?
I'll see if I can cap off the vacuum side of the carb that connects to this PAIR valve and see if that helps with the carb generating enough vacuum to start fuel flowing.
 
#11 · (Edited)
If the pair valve is not holding vacuum (it would have to , to work properly), then it needs to either replaced, or properly deleted. It is not going to effect your fuel flow, but you will have other problems. Edit: As ducatiman already stated.
 
#12 ·
All good. Thanks everybody for input and suggestions.
Seems that the fuel filter is the problem. Removed it, connected the hose directly to the carb and the tank.
Looks to be working fine now.

In my slight defense, the filter was there when I bought the bike a couple of months ago, so didn't think it was a problem until it started stalling and I re-built the carbs and ran into this issue. Not sure why it was working before and stopped after carb rebuilt, but at this point the bike is running without the filter.
 
#14 ·
All good. Thanks everybody for input and suggestions.
Seems that the fuel filter is the problem. Removed it, connected the hose directly to the carb and the tank.
Looks to be working fine now.
Know that the same thing may happen again. Running without a filter will let the particles into the carb, where they will lodge under the fuel valve ("needle and seat") and flood the engine with fuel.

Check the tank and drain/clean if necessary, then install a new (clear) filter and keep an eye on it.
 
#17 ·
A stall while running could also be a result of a vacuum being created in your gas tank. There is a valve system in the fuel cap that can go bad over time.
Standard recommendation is to get rid of it to avoid issues down the road.

John Z.
 
#18 ·
Bike came with a pos aftermarket "screw-in" tank cap. I replaced it with also an aftermarket (ie cheaper) normal cap with the key and a plug. I don't think vacuum in the tank is an issue. I'm hoping that I'm not getting this anymore, but if it stalls on me again, I'll see if opening the tank will get her running again. Thanks.
 
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