Only running 50 mph and then shutting down

[ivankifa]

My 2009 Lance Vintage has good power but running at around 45 mph for maybe a quarter mile it will just shut down, drops down to around 15 - 25 mph (total loss in power) let go of the throttle for a few sec and then picks up and runs back up to 50 mph for another shot distance and shuts down again, If I hold it around 45 mph will have no problem. Runs fine except for the cutting out at 50mph.
Help is requested. Thanks.

Let me know.

[choicemopeds]

The first/simpliest thing I'd try is loosening the gas cap. Then I'd consider trying alternative for the air supply. Someone told me once the cdi can cause your situation as well.

[ivankifa]

I tried loosing the cap, still same problem.
what would be my alternative air supply? so trashing the current air vacuum system?
can anyone steer me the right direction?
Anything will help.

[qwertydude]

This is one of the most common problems with 150cc scooters.

The cause for this is a combination of poor vacuum pulses and a crappy fuel pump. The vacuum system is so poorly designed with so many T's coming from a single vacuum source that the vacuum operated fuel pump can't work at high RPM's.

The solution is to first isolate the fuel pump and give it it's own vacuum source. On the intake manifold is usually two vacuum nipples and often times one is simply blocked and the other is used to supply all the vacuum. Many people just to simplify things remove the entire smog canister and all the hardware and block the pair vent from the exhaust.

Then the only things needing vacuum are the carburettor air cut valve and the fuel pump each will have a dedicated vacuum line with no T's if you remove the smog equipment.

Now the actual solution is to run as short a vacuum line as practicable to the fuel pump with no T's splitting off that vacuum line and most important is get a quality fuel pump. The Mikuni worked best for me.

www.amazon.com/Mikuni-Single-Outlet-Rectangular-DF44-227/dp/B000HS8RRI/ref=sr_1_1?ie=UTF8&qid=1358041803&sr=8-1&keywords=mikuni+vacuum+fuel+pump

That should fix it.

[rockynv]

The Vintage can be impacted by fuel starvation at speeds over 45 by cracked or loose fitting vacuum lines, ethanol clogging the fuel pump and intake elbow not tight to the head or fitted loose to the carb.

Start by verifying that the vaccume lines are in good condition and the intake is in place and adding 1 to 2 ounces of Lucas or Berryman's fuel treatment to the next few tanks of gas.

Next is valve adjustment which once it gets off will cause a loss of intake vaccuume so the fuel pump won't be able to keep up at higher speeds.

Due to the body style of the Vintage the ignition pickup will get overheated and fail to fire occasionally when it gets hot. This will only continue to get worse over time until you replace the pickup unit under the flywheel cover on the right side of the bike. Scrappy Dog has them for less than $20.

My Lance Vintage cutting out issues were mostly solved by regular valve adjustments and monthly fuel system treatment with Lucas or Berryman's after replacing the igition pickup.

After that it would only cut out at extended speeds over 60 mph or on long extended inclines. I weighed about 255 to 265 when I owned the Lance.

[Deleted]

A fuel pump is a device that either through mechanical or electrical power moves fuel by physically pulling or pushing gasoline from one location to another... It is my understanding the fuel in these scooters is gravity fed, the fuel flows down from the tank through the rubber line and the filter on to the carburetor's bowl float mechanism so there is no fuel pump, to prove that fuel flow exists simply disconnect the line at the carburetor.

That might be worthy of a test, but be ready with a rag and be ready to shut it off because if it flows freely, flow it will. Disconnect the fuel line at the carburetor and see if fuel comes flowing through, if it does your problem likely lies in the float bowl mechanism, an improper air supply, or a vacuum leak.

[qwertydude]

I remember looking at the Lance Vintage the fuel tank is in the floorboard. All scooters with floorboard gas tanks need fuel pumps to pump gas up to the carburetor it's not gravity feed.

The fuel pump though isn't electric so that confuses some people thinking it's a simple petcock but it's a fuel pump and it requires the vacuum pulsations to work properly. The way they have the vacuum system set up is very poor and the pump itself is of low quality causing fuel starvation issues at high rpm.

[rockynv]

The Lance Vintage has the fuel tank under the floor boards and uses a vacuume pulse operated fuel pump. The fuel filter can also get fowled but usually my problems with the Lance Vintage 150 were ethanol related fowling of the fuel system which were corrected with regular applications of a decent fuel system treatment. It is basically the same Znen bike as the Puma Elvis with 10" wheels. The valve seats were a little soft so that the valves did need adjusting more often and if you did not keep up you would also have fuel starvation issues at higher speeds or loads.

I owned one for 1.5 years and used it as a daily ride on a 20 mile commute to work.

If you kept up with the adjustments and such the bike was Ok but it was finicky at times.

[ivankifa]

I really don't know where to begin. Thank you for all that helpful info

There is a lot of work to be done from what hear.

I'm also spitting out oil from somewhere, cleaned it up but still haven't found where its coming from, it looks like it coming from where the fuel tank cap area. but don't know exactly.

Could it be the reason why its acting up at 50mph?


Again I appropriate all the advise.

Attachments:

[beachbum]

You can get a high flow mikuni fuel pump that has two lines from the pump. Use a "Y" to bring it to your carb. I had the same problem.

www.scootertronics.com/mihiflfupufo.html