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Post by brob305 on Dec 28, 2017 13:13:00 GMT -5
Ok so one night I was riding and my scooter just turns off. I have a clear fuel filter and I noticed there was no fuel flowing. Checked the petcock and it works fine but replaced it anyways. Checked and replaced vacuum lines and still have the same issue. But starts right up and runs fine until it warms up. Then fuel will stop flowing. Replaced carb 3 times and still the same problem. Any help would be appreciated cause I'm lost at this point.
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Post by lilpinny on Dec 28, 2017 13:22:30 GMT -5
Is your vacuum line a good thick rubber? I’ve seen some after market lines that flex too much esp. warm and it loses vacuum. The colored ones have too much flex.
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Post by brob305 on Dec 28, 2017 13:45:11 GMT -5
Is your vacuum line a good thick rubber? I’ve seen some after market lines that flex too much esp. warm and it loses vacuum. The colored ones have too much flex. fuel and vacuum lines are just standard issues ones. No special "high performance" colored lines. |
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Post by lilpinny on Dec 28, 2017 13:55:55 GMT -5
Hmmm. So you know that the problem is that it’s not getting any gas. To me it sounds like it’s the lack of vacuum or a blockage. Sounds like you have ruled the blockages out.
When you start it and it conks out, can you just start it again after a while, or do you have to wait and prime the lines and use starting fluid to get it going?
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Post by brob305 on Dec 28, 2017 14:00:20 GMT -5
Hmmm. So you know that the problem is that it’s not getting any gas. To me it sounds like it’s the lack of vacuum or a blockage. Sounds like you have ruled the blockages out. When you start it and it conks out, can you just start it again after a while, or do you have to wait and prime the lines and use starting fluid to get it going? after there is no more fuel in the line and it dies, if I wait 10-15mins I can see the filter fill back up with fuel and it will start right up and ride fine until the motor gets warm again. Then the fuel will stop flowing and it will die again. |
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Post by brob305 on Dec 28, 2017 14:01:57 GMT -5
I even drilled out the petcock so it would be gravity fed instead of vacuum fed. Still same issue.
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Post by lilpinny on Dec 28, 2017 14:07:26 GMT -5
Your fuel pump might be jacked. Vacuum pumps can goof up.
I’ve read about a trick, never done it. Start it and suck on the vacuum line to create the vacuum. Plug up the vacuum nipple on the intake with a vacuum cap.
Trying to figure out if the vacuum pump is dying when running or the carb is letting too much air in. If it’s a pump (like a mikuni) that you can swap easy you just might want to try that.
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Post by brob305 on Dec 28, 2017 14:58:00 GMT -5
Your fuel pump might be jacked. Vacuum pumps can goof up. I’ve read about a trick, never done it. Start it and suck on the vacuum line to create the vacuum. Plug up the vacuum nipple on the intake with a vacuum cap. Trying to figure out if the vacuum pump is dying when running or the carb is letting too much air in. If it’s a pump (like a mikuni) that you can swap easy you just might want to try that. I basically bipassed the petcock and still does the same thing.even if I ride with the gas cap off to help vent it still will do the same thing. |
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Post by lilpinny on Dec 28, 2017 16:02:41 GMT -5
I’d maybe try swapping the pump.
You cleaned out the tank and made sure there was no junk in there?
Either that or you have an air leak somewhere that’s showing itself when the vacuum builds up when it’s running.
How long does it run for before it dies?
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Post by lostforawhile on Dec 28, 2017 16:31:04 GMT -5
is this gravity fed or a fuel pump
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Post by 90GTVert on Dec 28, 2017 16:33:31 GMT -5
It really sounds like the petcock (most of these don't have a pump, but just a vacuum petcock as long as the tank is above the carb). I'm not sure why it would do that though if you have drilled it out to bypass it, assuming like the link below shows : 49ccscoot.proboards.com/thread/18187/vacuum-petcock-manual-conversionMaybe check fuel line routing. It's best if it is fairly steady downhill without high spots. I'd check float height too, just to cover the bases of fuel delivery. |
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Post by lilpinny on Dec 28, 2017 16:42:34 GMT -5
Huh... you don’t have one of these things?  It just sucks it right from the tank.. interesting. I learned something today. |
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Post by 90GTVert on Dec 28, 2017 16:52:08 GMT -5
Not sure what his scoot has, but in most carbureted scoots the pumps are only used with tanks that are level with or below the carb... like the one in the floor of your Ruckus. Of course fuel isn't going to defy gravity and flow uphill, so they have to have the vacuum pump to move fuel.
When the tank is above the carb, then fuel is moved by gravity feeding. All the vacuum is used for in the petcock is to operate a mechanism to shut off fuel with no vacuum is present and allow fuel to pass by when it is present. I am not a fan of these things. They seem to too commonly be a point of failure. I swap all of mine to a manual shutoff valve of some sort. The only real advantage of the vacuum petcocks is ease of operation for the average user... that is till the petcock seemingly inevitably fails one day.
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Post by lilpinny on Dec 28, 2017 17:09:50 GMT -5
The vacuum pumps fail too... the one in the pic is still in its bag in my spare parts bin waiting for the day it’ll be summoned into use. 😁
Stock rucks have an electrical pump that is also the source of many failures.
Sounds like the petcock has its issues as well.
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Post by km4nxa on Dec 29, 2017 11:42:51 GMT -5
I know you've in a round about way bypassed the petcock, but really need to try doing away with it all together. Straight hose from bottom of tank to filter to carb. If it still has same issue, just go straight from tank to carb, bypassing filter. If still same after that, I'd replace the fitting that threads directly in tank. There's a small screen located on it. Maybe some weird situation going on with that. Doesn't make much sense if so but seen weirder things happen. Eliminate each variable one at a time.
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