Problem Surging 257cc By damin69 (Read 3,784 times)

[damin69]

Ok So I took my scoot to work today 63 miles each way. Temp this am was about 40 degrees. Scooter ran great all the way in. Now is where the problem starts. I left work it was 72 degrees. Scooter started up ran great all the way over to the mall to take picture for TAG. Then ran great for another 20 miles I had to stop to do a battery pull on GPS that had locked up. Just left scooter idling still running great.

I then take off running about 57 mph at about 5200 rpm and the scooter looses power I let off power comes back I ease back on it surges again. So pull off in a park n Ride open up that seat and richen up the AF one half turn. I had it set at 2 1/4 turns out already. Well take off from there all seemed to be good for about 35 miles then all of a sudden it starts major surging like it is starving for fuel then the poer comes back. I let off the throttle then just ease back on and was able to get back to cruising speed.

I have no Idea where I need to start to trouble shoot something like this. HELP please.

[Alleyoop]

Sure sounds like fuel problem, maybe the Fuel Pump or Petcock depending on what you have is acting up and not filling up the bowl quick enough. Have you checked your Vacumm lines for any weak connections and or leaks. Did you maybe Overfill your gas tank and the vent has gas in it and not venting stopping fuel flow.
Alleyoop

[damin69]

Yeah I had checked the vacuum lines the other night I had one line that I put clamps on that seemed loose. I filled it up this am Tank was at about 3/4 when it started acting up. Do not know of a Pet cock on the scoot. I put new fuel line from tank to filter to pump then up to carb is all new fuel line. Does not mean that it is not the pump causeing the problem though.

Maybe I should think about putting an electric pump on. Where is a good place to get a reasonable priced electric pump?

[ce]

Did you change the Y's or T's in the vac lines? Make sure they're 3/16 and not 1/8 or at WOT you won't have enough vacuum to keep the pump supplying the fuel bowl. You might get better vacuum with the fuel vapor recovery line T'd to the air cut off valve on the carb, and the pump on a single connection to the manifold.

Or just remove the fuel vapor system and have one less connection. You have a different carb than what's on the 54B, I have a 260 VOG like yours, and I removed that stuff and haven't had any fuel starvation.

Check the float level too

[damin69]

Thanks guys. Give me some areas to start looking at. Going to be raining for the until next week now so have some time to sort it out.

[Cruiser]

This is the best deal on a Mr. Gasket 42S fuel pump that I could find.

[mcalli]

An Electric fuel pump sounds like a good idea. What problems does it solve? Would it help solve an idle adjustment for example. Is it computerized. Does it adjust fuel flow depending on what the bike and its components are doing? I would love to have information on this little item.

[speedracer]

Reply #4 You bring up a subject I was wondering about. Do our scoots really need those extra vacuum lines going to the fuel vapor system? They go into it, but there is no hose going back to the engine or carb that I can find. Without them on, one vacuum line to the carb and the other to the fuel pump correct?

[royldoc]

It does sound like a fuel problem. When was the last time you filled up and do you use an additive? quick test, pull the fuel line off carburetor and put in glass jar let some fuel run into jar and check for water. This may not be the problem but it is easy test. I like to eliminate the easy stuff first.


Roy

[damin69]

Apr 13, 2011 18:54:57 GMT -6 ce said:

Did you change the Y's or T's in the vac lines? Make sure they're 3/16 and not 1/8 or at WOT you won't have enough vacuum to keep the pump supplying the fuel bowl. You might get better vacuum with the fuel vapor recovery line T'd to the air cut off valve on the carb, and the pump on a single connection to the manifold.

Or just remove the fuel vapor system and have one less connection. You have a different carb than what's on the 54B, I have a 260 VOG like yours, and I removed that stuff and haven't had any fuel starvation.

Check the float level too

CE

What did you have to do to remove the Fuel Vapor system? just take the T out and connect the Vacuum line to fuel pum directy to the Vacuum port on motor?

[ce]

Yeah, that's it, just connect the vacline straight from the port to the pump and abandon the vapor system.

Stick a golf tee in the line from the tank and make sure the gas cap is vented. They usually are, but if not drill a tiny hole in the top.

Sometimes there is only a charcoal cannister, sometimes there is another vent tube to the air box, just seal or plug any open lines once you track down the whole system to keep the valve cover vent working at the airbox.

It's pretty simple once you get started, and if you're not sure, don't destroy anything until you're sure it's extranneous.

I think Bashan posted a bunch of pics and descriptions under "Motorino Maladies"in Tech Help.

[damin69]

Thanks. I will look into all of this On the weekend when i have some more time to check it all over. I will get it all sorted. Going to be crappy pretty much for the next 7 days so not going to be riding anyway but do want it ready to go when this weather does decide to warm up and stop raining.

[brndnpnt]

before you go changing and fooling with all the hard stuff to fix do this take off the intake from the carb and put it back on tight and do this all the way to the air box and that should be a rap. sounds to me like an air leek throwing off the air fule mixture which you think it is also so try the air box down to the carb

[Cruiser]

Apr 14, 2011 5:25:15 GMT -6 mcalli said:

An Electric fuel pump sounds like a good idea. What problems does it solve? Would it help solve an idle adjustment for example. Is it computerized. Does it adjust fuel flow depending on what the bike and its components are doing? I would love to have information on this little item.

The pro/con analysis can give most of the highlights on the electric fuel pump. These pumps are not computerized and do not have pressure regulation.

PRO:

1. Steady fuel supply regardless of engine rpm. Vacuum pumps tend to have a drop in output as the engine speed increases.

2. Pumps as soon as the key is turned so that carb priming is not necessary. Ensures faster starting after a long shut down like winter storage or when the carb has been drained for maintenance.

3. Vacuum leaks do not affect output of pump.

4. Higher pumping output than a vacuum pump.

CON:

1. Uses electrical power (about 1 amp) which can be a problem on marginal charging systems.

2. Higher price than OEM vacuum pumps.

[speedracer]

I don't think its a fuel issue at all. You went over a 120 miles the same day plus new fuel lines and filter. Vacuum line possible, but how about a coil issue? A loose coil connector at coil or at cdi. Or a overheated coil.