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Post by oscar on Oct 5, 2010 20:53:35 GMT -5
Been having this trouble running out of fuel in the bowl after startup & while making the slow climb up my driveway. I had thot this was the vacuum fuel valve not getting enough vacuum but then today the scoot started stuttering in its midrange again. (Been an on & off problem.) Also bogging at WOT. Pulled over to the side of the road & was looking things over & noticed the fuel filter was full of air w/ just a smidgeon of gas at the bottom. Tried to release the vapor blockage by pulling the fuel line off the top of the filter but no joy. Got home & let the scoot set & noticed as it sat over time I could actuate the fuel line valve by sucking on the line & gradually the filter would take on more fuel. Felt the bottom of the carb & it was quite warm but the rest of the carb & fuel line were nice & cool. I'm guessing vapor lock coming out of the bowl.
Anyone else ever have this problem?
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Post by als01seville on Oct 5, 2010 21:14:36 GMT -5
Sounds more like a Vacuum problem from either your intake hose and or your Petcock or your Fuel Pump has a problem. To test your pump or petcock, take the vacuum hose off and take the fuel line off the carb and put it into a glass and suck on the Vacuum hose. Fuel should STREAM OUT and not Dribble out.
Alleyoop
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Post by tomcas on Oct 5, 2010 22:36:55 GMT -5
One thing is for sure, you are not vapor locking because of a warm bowl. It sounds more like the tank isn't venting. Leave the gas tank cap loose and see what happens.
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Post by oscar on Oct 5, 2010 23:41:28 GMT -5
Yeah took the tank cap off while I was along side the road. When I pulled the line off the filter it released fuel w/ fuel valve actuated but once I placed the line back on the filter it would not fill the filter. The only thing that put fuel back in the filter was time to set after being run.
Smells like a vapor lock, looks like a vapor lock, & quacks like a vapor lock...
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Post by D-cat on Oct 6, 2010 0:09:26 GMT -5
Is this a larger than stock fuel filter? This problem has been reported sometimes when using larger fuel filters designed for high power lawn mowers. I'm not really sure why, but replacing with a smaller filter might help.
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Post by als01seville on Oct 6, 2010 0:49:00 GMT -5
Also the fuel filter could be backwards that would restrict the fuel from coming in quite a bit.
The Fuel Filters Usually have a wider part on one end THAT part should be connected to the Carb side.
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Post by tomcas on Oct 6, 2010 7:33:48 GMT -5
Dcat and Al have good points. You should perform the fuel delivery test that Al suggested to rule out any of these problems. If the fuel delivery checks out then its time to reinspect the carb for proper float setting, functioning of the float valve, and venting of the float overflow tube.
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Post by scootercapecod on Oct 6, 2010 8:53:43 GMT -5
It's no doubt a fuel delivery issue. the petcock may be OK BUT..... you may not be getting a good vacuum so the petcock acts like it is faulty when it could just be the line itself isn't completely sealed.
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Post by oscar on Oct 6, 2010 15:40:38 GMT -5
Had some indication it could be a siphon vent w/ the filler cap. Needs more testing which I'm about to do. Had originally thot it was a vacuum issue as I've been dealing w/ a couple vacuum leaks which I can't completely get sealed. It seems like when a void of air gets into that filter it really hangs in there. After the void developed again this afternoon I did the flow test prescribed earlier here. Flow was excellent but the air pocket/void in the filter remained. Going for along highway run w/ filler cap loose to see if that cures what is ailing my little scoot previously tested by leaving cap on 1 end of the highway run & then tight on the way back. The way back, the stutter redeveloped, so will see. Thanks for the input.
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Post by tomcas on Oct 8, 2010 15:10:08 GMT -5
It's no doubt a fuel delivery issue. the petcock may be OK BUT..... you may not be getting a good vacuum so the petcock acts like it is faulty when it could just be the line itself isn't completely sealed. Petcock valves are a lot more forgiving then one might think. These valves almost snap fully open with less than 5"Hg vacuum and will stay open until the vac drops to around 3"Hg. |
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Post by oscar on Oct 12, 2010 10:58:39 GMT -5
Now it looks like this problem is low output from the stator or regulator. Seems to take alot of current in the midrange to run the ignition as indicated by the poor output of the horn. Higher speeds & throttle reduction allow the horn to be louder. Need to install a battery here to see if that doesn't clean up my problems. A friend found that the wiring to the fuel tank sender was severed by the underseat panel. I found that the wiring was shorting to ground probably on 1 strand. Separating the wires provided a brighter light & better horn operation. Guessing this short probably damaged the stator or regulator.
Fuel still runs out in the filter but I ran along time 1 day on a mostly empty filter w/o any missing.
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Post by tomcas on Oct 12, 2010 19:21:40 GMT -5
Now it looks like this problem is low output from the stator or regulator. Seems to take alot of current in the midrange to run the ignition as indicated by the poor output of the horn. Higher speeds & throttle reduction allow the horn to be louder. Need to install a battery here to see if that doesn't clean up my problems. A friend found that the wiring to the fuel tank sender was severed by the underseat panel. I found that the wiring was shorting to ground probably on 1 strand. Separating the wires provided a brighter light & better horn operation. Guessing this short probably damaged the stator or regulator. Fuel still runs out in the filter but I ran along time 1 day on a mostly empty filter w/o any missing. I think your reasoning and assumptions may be wrong because the lighting and charging coils are completely separate from the ignition system and the fuel tank sender has a fuse before the battery. |
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Post by oscar on Oct 12, 2010 20:54:01 GMT -5
Nope not it. Idle was somehow improved w/ the addition of the battery. The longer I run the more the stuttering comes into play. Just casting about on this 1. Will go back to examining the vacuum issue. Ha why are these problems so difficult.
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Post by D-cat on Oct 12, 2010 21:22:16 GMT -5
Question: Do you know if your ignition is AC or DC fired?
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Post by oscar on Oct 12, 2010 22:33:37 GMT -5
Don't know but the stator circuit does this pulsing thing on the DC voltmeter.
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Post by oscar on Oct 12, 2010 22:34:42 GMT -5
The horn seems to pulse w/ the stator output when at midrange RPM.
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Post by D-cat on Oct 12, 2010 23:21:18 GMT -5
Stator output should not register with the meter set to DC, stator output is AC. The difference between AC and DC fired ignition is the power source for the CDI (and DC CDI's tend to be larger). The more common AC fired system gets the capacitor charge from the exciter coil in the stator, the DC fired ignition charges the capacitor from the battery. The AC system is not dependent on the battery; it can be kick started fairly easily without even a battery installed. The DC system however is more difficult to kick without a battery, or possibly worse with a low battery, because enough juice needs to be built up for the CDI to fire a sufficient spark. Thus, battery condition makes a negligible difference on an AC fired system, but can be quite noticeable on a DC fired system.
Now as far as the electrics having issues, this could be a wiring problem, possibly a bad engine ground or other ground. A bad ground will also cause battery charging issues, so the wiring should be investigated and any wires that are secured to the frame (should all be green except for the thick black battery cable) should be checked to make sure the connections are clean and tight. If those are all good, go through the whole harness looking for loose wires in connectors or damaged wires.
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Post by oscar on Oct 13, 2010 9:14:13 GMT -5
The stator generating coil was jumping all the way up 20 v on the DC meter. Prior to cleaning a couple of the ground terminals it would only jump to 14 v. Getting this kind of reading on the charging circuit leads to believe the regulator could be bad. On the positive side the stator was able to keep the battery charged on my 12 mile run yesterday though it didn't charge above the 3/4s charge I had already on the battery. The horn wouldn't work well until i installed the battery.
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Post by D-cat on Oct 13, 2010 10:33:35 GMT -5
That's a DC offset, and a big one; it means the stator's ground, or engine ground, is bad. A bad ground will also prevent the regulator from functioning properly (it has to dump excess current somewhere to keep voltage nominal). It is also possible the regulator/rectifier is bad (or being bypassed/shorted), so it may be a good idea to test this too. With the ignition off, set meter to ohms, and test against the frame the engine block and various green wires throughout terminals in the harness. Every one of them should read 0. If you get any ohms or no connection from any of these points, you have a suspect location; trace the wire back to see if you can find the cause. For testing the regulator, unplug and test continuity (ohms) according to the following chart:  |
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Post by oscar on Oct 13, 2010 10:40:40 GMT -5
I worked on the regulator ground but never tested engine block to frame. The ground terminal under the foot platform hasn't not been cleaned yet. Thanks for the diagram.
Looking for a online service manual for the 50cc scoots. Got 1 for the 150cc scoots but obviously not the same.
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Post by oscar on Oct 13, 2010 10:44:27 GMT -5
Am wondering about the routing of the fuel line coming off the tank. I have so much fuel line I have the fuel filter setting back by the air filter. Should the fuel line be as short as possible?
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Post by D-cat on Oct 13, 2010 11:11:01 GMT -5
Generic 50cc manual: www.scootdawg.com/downloads/GY6_50CC_MANUALscooter.pdfAFA fuel line, it should be short enough to gravity feed the entire distance. Suspension should be considered; you don't want it tight when the rear wheel is lifted off the ground, but you also don't want it in danger of hitting the rear wheel at full compression. |
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Post by oscar on Oct 13, 2010 11:55:45 GMT -5
10.5:1 ratio, 215 psi on compression check. Wow. Would think premium grade would be a must.
Only 2.2 hp (wow hard to believe its that low)
Thanks for the manual info.
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Post by D-cat on Oct 13, 2010 13:01:16 GMT -5
At least 91 octane, and you can pull more power out of that engine; 2.2 is restricted low end. Opened up (free flow) you should get about 3.5, throw in a BBK for around 5 hp (varies with size).
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Post by oscar on Oct 13, 2010 13:08:43 GMT -5
Do get a knock at low idle.
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Post by oscar on Oct 13, 2010 13:11:22 GMT -5
At least 91 octane, and you can pull more power out of that engine; 2.2 is restricted low end. Opened up (free flow) you should get about 3.5, throw in a BBK for around 5 hp (varies with size). Yeah mine goes 45-50 MPH so I doubt I'm restricted. My snowmobile wants 91 so I'll try it w/ scoot. Snowmobile only runs 7.5:1 or so I imagine because it has to burn oil. |
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Post by oscar on Oct 14, 2010 7:58:09 GMT -5
Shortened the fuel line, no help. Missing badly after startup & continues for a mile or 2 down the road until the cold start solenoid closes & then suddenly the problem is gone. I had checked the solenoid earlier & the little o-ring pulled out of its groove when I reinstalled the solenoid. Wondering if I have a bad seal & need a new o-ring.
I am wondering if my problem is being rich but I doubt it. Gotta get that spark plug out & check its color. Would have done this along time ago but its so hard to get at. Think I'll drill a hole in the plastic panel so I can access plug easier.
Sure alot of complaints of bogging w/ these beasts. Wonder what the common denominator is?
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Post by D-cat on Oct 14, 2010 22:17:12 GMT -5
Bogging is usually the F/A mix being off. With the changing seasons, it adds another level of complication trying to dial in the carb. Even I'm having a little more trouble than usual right now; there is no setting that works both in summer and winter, but if you can dial it in in the spring or fall, you might be lucky enough to have an acceptable ride for the solstice seasons.
Yeah, the autochoke gasket may well cause some problems. It's not really a solenoid, more of an electrically heated riser, but point taken. If it can't regulate the fuel through the enricher circuit, it's not going to behave. It probably was rich, but like you said, it's the plug that'll tell you.
BTW I saw a neat trick a shop used for the plug. While tightening down and breaking loose still had to be done by wrench, freehanding the plug was done by placing a couple inches of extra fuel hose over the plug top, then it spun like a flexible nut driver. They didn't even have to take the bucket out.
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Post by oscar on Oct 15, 2010 9:46:21 GMT -5
Is the ignition weak on these? My snowmobile doesn't bog when its off it just keep going faster & faster.
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Post by D-cat on Oct 15, 2010 10:40:25 GMT -5
I do often suggest getting a high-output coil and keeping a spare CDI handy. I don't know about "weak," but stock parts aren't known for their resilience.
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