Fuel Starving? By dn3616 (Read 7,381 times)

[dn3616]

Hey guys. Ive been having this problem for quite a while now. Im not very knowledgeable when it comes to scooters but i know a little bit about them. I have a longjia 125 (crapty Chinese scooter!) and lately i will ride my scooter for maybe 10-15 mins, and all will be fine THEN suddenly, the bike will start to splutter and feel like the bike is losing fuel, or just losing power. Its very weird and annoying as its my only transport to get back and forth to work. If anyone has any advice or help, i would be MORE than appreciated :)

I have cleaned carbs out before, replace spark plug, checked cabling, electrics checked, nothing seems to work though... :/

[jct842]

Fuel filter? or spark? Air filters too. You need to narrow it down. Could also have a vacuum side leak as in air getting into manifold. A vacuum leak can do all kinds of weird crapt like shutting down the fuel pump or petcock.

[dn3616]

Well i havent replaced the fuel filter at all. I thought that was fine. I could replace that cause i know i get one for cheap. The spark plug has been tested and it has a spark and the air filter hasnt been replaced but will be needing to be replace soon like.

I havent seen any vacumn leaks on my manifold. Its weird aswell cause ill pull over to the side of the road once my bike starts to do that, and the bike will be ok on the side stand, it will rev and will not misfire or splutter or anything, but once back on the bike, it will start up again.

[Bashan]

Your gas tank venting may be compromised especially if you have a vapor canister. Loosen the gas cap and take it out for a ride and see what it does. Rich

[Alleyoop]

Check under the seat there may be a hose being pinched with your weight.
Also next time it does it TRY THIS and that will tell which of the two is the problem LEAN OR RICH:

When it starts to act up BACKOFF the Throttle about 1/4 of an inch AND HOLD IT THERE.
a. If it speeds up it is LEAN.
b. If it sputters hesitate and settles down it is RICH.

Finding which of the two it is will help find the problem.
Alleyoop

[dn3616]

I havent tired the gas cap thing but i will try it next time its a nice day out

And with the post on the throttle, i usually do back the speed down until a find a right spot, and alot of the time it just splutters so what your suggesting is the bike is running rich?

[Alleyoop]

If you already have done that and it sputters, yes it is running rich. If you haven't messed with anything check your AIR FILTER a dirty air filter will restrict air and then it will run to rich.
Alleyoop

[dn3616]

I have been needing to replace my air filter but i have asked my uncle and my dad who are good with bikes and own bikes, and they say my air filter is preety ok. But i need to change the air filter as i have 4.6k miles on the clock and the air filter needs to be changed every 2k soo... needs a change i think

Thanks for all the help guys Anymore adivce will be amazing ><

edit: Also, it seems the problem happens when i have to accelerate above say 40-50 for a good 10 mins or so. Sometimes even after a few miles it happens more. The chance of it happening then greatly increases it seems

[kepps1280]

I had problems like that. After checking everything that was visible, and changing the filter to a larger one, I finally changed the fuel pump. problem immediately disappeared. $12 well spent on ebay

[sprocket]

For $12 that is a petcock...new fuel pumps on EBay run round $30 ...they have different functions...

[dn3616]

Quick update, went out on the bike today to get home from my girlfriends house. Normally, this ride would take me 30-40 mins to get home... It took me nearly 2 HOURS to get home! I had to keep stopping and starting as the bike was basically unrideable. I removed the carb and checked the jets and one was blocked, so i blew the dirt out and everything else was fine. Put it back together everything was fine. I also adjusted the air/fuel mixture screw.

I started to ride the bike home again and everytime i was slow enough so i nearly stopped, the bike would cut out completley! This happened several times and one nearly ending up in a collision with a car. Im not comfortable enough to go out on this bike. I think it could be the idle scew is incorrectly adjusted but i will try more stuff out on it tomorrow.

Im gonna get a new air filter soon and try that out, also a fuel filter

[sprocket]

I don't think Chinese scooters are snitty...actually for the price, they are great! Have you completely flushed the tank and fuel system? Cleaning the carb, does nothing you need to clean the system and replace the fuel filter...sounds like the petcock, or fuel pump...check you vacuum lines.

[dn3616]

Yeah i think some are aswell. When my bike works, it runs amazing! It just pisses me off when this happens... Its really weird, and im just gonna have to get the parts for it

Why would the fuel tap/petcock fail?

[sprocket]

They are run from vacuum ...hoses leak or the petcock diaphram gets a pinhole...very common...

[dn3616]

Ahh right ok Well i will makes those changes to the bike, ive found everything online and i will try the air filter and fuel filter firstly, and if that doesnt work, ill buy the petock as its more expensive that the air filter and the fuel filter together