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Post by mgreenfield on Jul 19, 2006 8:48:55 GMT -5
My new GY6-powered Roketa Jamaica-150 is VERY hard to start sometimes. Sunday night it died as I was riding it in the neighborhood, and WOULD NOT restart. Pushed it home. Last night I verified bright blue fire at the sparkplug, and fuel in the carburetor. Wouldnt even sputter.
Sprayed starting fluid into air-cleaner box (which has worked in the past), still no sputter even. Put scoot on battery charger and went to bed.
(FYI the battery is inaccessable, so I connected the charger at the starter solenoid in the trunk compartment, which I had open anyway. Red lead to red lead. Black to ground on a bolt.)
This morning it cranked a couple times and started right up. I cranked it with throttle closed. It caught when I gave the throttle a tiny "blip". Ran a little rough. Died a few times, but finally warmed up and smoothed out. Took test spin with no further problems.
It seems likely to become hard to start when the engine dies for some reason rather than being shut off with the ignition.
What's up with this?? Are these engines easy to flood??? Really weak OEM sparkplug???
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Post by subarutech on Jul 19, 2006 19:51:01 GMT -5
as stated in your other post i have the same scooter with same problem.the auto choke is not the best at metering fuel.just always crack the throttle to let more air in if it doesn't start without applying any throttle.its seems as i get more mileage on the motor the piston rings are sealing better creating a better combustion.and now is starting much easier without opening the throttle as much as i had too.
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Post by mgreenfield on Jul 20, 2006 10:27:01 GMT -5
Think I may have found the TWO problems causing this.
1/ If I set the idle a little faster than I'd prefer, it starts better. Apparently it likes a little more air to get going.
2/ THIS IS THE BIG ONE. Originally the fuel line rose from the vacuum shut-off valve, ran over the heat shield that's right over the engine and right under the fuel tank, then DESCENDED slightly to the carburetor inlet. The fuel had to "go up a little hill then back down". FURTHER, the lower part of the line was quite close to the exhaust emissions air-injection reed valve, which is pretty hot. I figure the fuel picked up heat at that point, and created a vapor lock at the top of the little hill, which shut the scoot down.
I re-routed the fuel line so it's away from the exhaust as far as I can get it, and so the run from the vacuum shut-off to the carburetor is just one smooth rising slope. Bingo! No more stalling and hard starting.
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Post by Admin on Jul 20, 2006 17:18:06 GMT -5
I think the vapor lock was the biggest part of your problem but who knows? Good work.
I've seen three posts on various forums in the last two days about the routing of the fuel line going over hot spots causing vapor lock. Maybe the hot weather is adding to the problem.
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Post by subarutech on Jul 24, 2006 19:18:10 GMT -5
just to update mgreen.i bypassed the vacuum valve and ran a short fuel hose from tank to the carb inlet fuel supply.still the same problem.i dis connected the choke and still same problem.i have to open the throttle to get the motor to start and keep it running till it is warmed up.now if i disconnect the fuel source and run the scooter just off the fuel in the bowl it will start fine and idle excellent.this is after it has burned off the some fuel from the bowl.im thinking the float level is too high causing a over rich mixture.when the motor is hot it runs fine.i think this is due to the hotter engine temp atomizing the fuel better even though the float level is high.made a post for float level specs with no luck.so im going to take the carb off and measure it level.then make small change from there till i get it right.will post back.good luck.
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Post by subarutech on Jul 24, 2006 20:46:25 GMT -5
hey mgreenfield,found the problem,starting a new post in tips -tricks,will have picks and problem found.in short binding/sticking float. you dont live that far from me.if you wish i could stop by and we can get this squared away.
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Post by mgreenfield on Jul 25, 2006 7:40:13 GMT -5
Dawg, ....re hot weather & vapor lock. That was my tip-off. On 90+degF day it happened very soon after starting/running. On 70degF day wouldnt happen at all, unless left the scoot idle for a while. When the whole thing cooled down completely the scoot would start again just fine, .....as long as I had plenty of gas in the tank. This made diagnosing the problem pretty tricky.
Suburutech, ....let me fiddle with it a little more before putting out an SOS. I'm actually another 45min north of the Milwaukee airport. The scoot starts/runs fine, ....as long as there's more than 1/3 of a tank of gas, and I understand that this problem has been seen before. ALSO, I used your format & posted a fix for vapor lock in the tips/tricks section!
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