Scooter won't stay running By beo111 (Read 39,213 times)

[beo111]

I've run into this same problem again. I few months ago I posted that my 50cc scoot wouldn't start after storing it for the winter. I cleaned the carb inside and out and it ran great. I haven't been riding it because I have another scoot, but I tried to start it today and it turns on then dies after a few seconds. I took the carb out and cleaned it out and put it all back together but the same thing happens. Here is what I did also:

1. Checked the battery for 12V
2. Checked the vacuum hoses for leaks
3. Checked for spark (have a nice blue spark)
4. Checked forf compression with my finger and there was
pressure
5. Adjusted the valves, they were almost closed so I made
them .004 top and bottom

One thing I must mention is that while cleaning the carb I assume the bigger jet is the main jet and the smaller is the pilot? Well, I clean out the jets with carb cleaner and use a tiny wire to make sure none of the small holes are clogged. I noticed with the smaller jet I can't get the wire all the way through. Is the hole supposed to be that narrow that the wire can't get through?

By the way, I've had the same gas in the tank since November but I used sta-bil for the for that non-riding time. Could that be a reason it starts then dies? I'm looking for any help!!!

[sprocket]

Sta-bil doesn't work in scooters... I wish people would drain their tanks... it only takes 2 minutes.

Anyhow... you need to flush the entire fuel system, tank, petcock/pump hoses...pour in 1/2 bottle of STP fuel injector/carb cleaner into the tank and get it through the system... then add fresh gas to the tank... 87 AKI octane .. not premium.

Now.. clean the carb again....

Some pilot jets are not open on the top but have many little holes on the sides...soak your jets in the STP cleaner and then run a wire through the holes... soak the body of the carb too and get cleaner into the carb passages...

Reassemble and you should be good to go...

[beo111]

Thanks sprocket, I assume I'd have to remove the petcock entirely to drain it? Or is there an easier way? With my 150cc, I can just remove the gas line from the vacuum pump and the gas will drain out of the hose. This 50cc is above the carb with the petcock, so I'm just wondering if there is a trick to this before I have gas all over the bike and floor!!

[Bashan]

Is your petcock screwed into the tank? If it is, that's going to make it somewhat more problematic to drain. You'd have to put a slight vacuum on it with a syringe to open the valve (see below). If the vac/fuel valve is a little puck about halfway down the fuel line to the carb just pinch the hose before it and pull it off. I agree with everything Sprocket said and will note the tip about the fuel injector cleaner, I didn't know that. Your main jet is the one that has the needle come through it. You can see the holes in the jets if you hold them up sideways to a light, they should all be clear. You've got spark and compression, if it was me, I'd check the fuel flow. Rich

[beo111]

Thanks for the responses, I definitly know it's not a fuel flow problem. I bought the see thru glass fuel filter from autozone and I can see that it's full of gas. When I crank it I can see the gas moving down the tube and refilling the filter. The carb had plenty of gas in it when I took it apart. Also, the petcock is screwed into the tank.

[beo111]

Well I just took out the carb and cleaned it out again thoroughly. I took out the main and pilot jets and made sure all tiny holes were clear. cleaned every hole and passage of the carb. I drained the old gas out and got the STP fuel injection cleaner put it in the tank and got it through the system. I put in fresh gas and went to start it and the same thing happens. Starts for a few seconds and then dies. I still have 12.5V on the battery and spark. I'm sure it's one thing that I'm missing somehow. What am I doing wrong?

[Bashan]

Try a few things one at a time and see what it does.

• Take the vacuum hose off of the "T" and squirt a little carb cleaner down into the intake manifold. Reattach the hose and crank it.
  
• Bypass the vac fuel valve by putting a splicer in the line.
  
• You cleaned your carb a while ago and it fixed it. This time it didn't, maybe something happened during the process. You checked your vac lines but look carefully at the intake manifold and make sure there's no cracks and the carb is secure.
  
• Make sure your autochoke is secure and it's plugged in.

Rich

[beo111]

I don't have a T-connection on this bike, but there was gas in the manifold when I pulled it apart. The manifold wasn't cracked or damaged. Also, what do you mean by bypassing the vac fuel line and putting a splicer? What am I checking for there? I put together a video in the meanwhile just so everyone can see.

[beo111]

I believe I found the problem. I decided to look again at the possible vacuum issues, and I took the intake manifold off again and saw that the black plastic gasket under it has a slight crack on it. I will order a new one, but I'm hoping that this was it. It could have happened when I last put the manifold back on because I didn't look at it before. Can a slight crack in it still cause a bike not to start?

[jhbietz]

Even a 150 is a very small engine. If there is much of a vacume leak it won't run correctly. Replace the plastic spacer and then follow the directions listed above. You will have it running it running in no time.

[Bashan]

Hey pal, we can't do anything around here without some damn pictures to go by!!! Kidding! Great job on the video, you've really did good work AND your homework. That canister is a stupid pollution device and is just a potential vacuum leak IMO. If it was mine I'd plug the vac line that supplies it and remove all the crap, but that's just me. To splice your fuel line and bypass the vac valve for testing purposes, get a brass 3/16" or 1/4" splicer at Lowes and unhook both fuel lines going into the vac valve. Splice the line and see what it does, if it makes a change your vac valve is bad; it happens all the time. That wire hanging down by the valve cover looks like a turn signal wire, I don't know how it got down there. Bike factories leave empty wire connections all over the place that are used on other models, don't worry about those on the back. Replace the manifold spacer and make sure you use a gasket on the non O-ring side. If that doesn't get it don't worry, this is a process of elimination and we'll get through it. Let us know what happens. Rich

I found a pic, pull the line off of each side of the valve and use the splicer to join them. I'd see if the spacer fixes it first though.

Splicer:

[beo111]

Thanks for all of the suggestions. I guess there is hope for this scoot! My scoot has a petcock connected on the tank so it looks like the splicer won't work that way. I did see a thread one time where someone removed the petcock from the tank. He added an elbow fitting, and relocated the fuel valve to a place similar to what's in the picture above. Maybe that's an option I should look at!

[Bashan]

Oh yeah, I forgot you said you had a petcock...sorry. That's unusual on a 50cc. Did you see the syringe test on the fuel flow test link? That's another option. I use manual valves on most of my scooters, it removes a potential problem. You do remember to turn them on after you run out of gas a few times. Rich

[beo111]

I didn't have a syringe, but I have a hand held vacuum pump. I used it on the vacuum line to the petcock and put the fuel line in a container and gas came out. I'm going downstairs to squirt some gas into the intake manifold and see what happens.

[beo111]

I mentioned this in the video, but do you know what this small rubber piece is? I found it next to the scoot and it might be the source of my problem also. It's some sort of a one way tube (10mm long), like a check valve. I can blow through the side with the hole, but not the other side. It must have been in something, then fell out when I originally worked on it. Looks familiar?