GY6 Engine coughed, then died By Steve (Read 8,990 times)

[Alleyoop]

Lets now check if the carb is allowing enough fuel to fill the bowl:

Connect the fuel hose back up and now take the CARB DRAIN HOSE and stick that in the container.

OPEN the CARB DRAIN SCREW counter clockwise( the fuel in there will drain out).

Again crank the motor over and gas should keep on coming out of the Drain hose.

You can also try loosening the fuel tank cap from the locked position to see if maybe the tank is NOT VENTING and once it builds up pressure it does not allow fuel to flow.

Alleyoop

I do not like those PETCOCKS because of the Plastic tubing inside that can get clogged and not allow enough fuel to free flow.

I would drain the tank and take that sucker off and check the plastic filter and or remove the damn thing you have a fuel filter that I see and its a good one VISU type you do not need 2 fuel filters especially that one which is very restrictive.
Alleyoop




ALSO reposition the FUEL line it is gravity fed and must not have any ups and downs. I would take the line from the frame and cut the hose by the carb to make a straight DOWN shot to the carb.

[Steve]

Thanks, John.

Do I need one with a switch? The one I have doesn't have one.

How would I install either one of those you identified?

These two look like the one I have:

www.pccmotor.com/gas-fuel-tank-petcock-for-50cc-49cc-moped-scoote504904.html

www.chinamotoparts.net/gas-fuel-tank-valve-pump-petcock-50-150cc-scooter-atv-dirt-bike-p-871.html

They look easy to swap out. ;-)

< Steve >

[tvnacman]

just unscrew it , I have both ready to ship from NY .

John

[Steve]

John,

Allow me to re-phrase: How would I install the ones that don't have a nut that I can use to attach the petcock to the bottom of the tank?

Second unanswered question: Do I need a petcock with a lever?

Do appreciate your help!

< Steve >

[tvnacman]

I have the replacements that mount under the gas tank . You can use the air actuated valve same as the factory one . Or if you want to mod it to the one with the lever . Can you see the valve when all of the plastics are assembled ? If you can the one with the lever would be great .

John

[Steve]

John,

I can't see the petcock with the plastic on. The vacuum activated is my preference, anyway. Is it as efficient?

This is the one you have listed under the 150cc size: www.testedscooterparts.com/product_info.php?cPath=1_9_32_279&products_id=10561927

The one you provided me a picture of is from the 50cc listing.

I only have two hoses to connect to it...

Which is the one I need?

< Steve >

[tvnacman]

it is a miss print the 50 and 150 use the same one

www.testedscooterparts.com/product_info.php?products_id=10561928

John

[Alleyoop]

Yep, if you cannot get to the shut off valve then you cannot use one of them. But if you modify it and put one of these on then you can run you gas line from the tank to a Petcock or a Fuel Pump or a Cutoff fuel valve and where it is easy to get to.

The parts are for gas lines at a hardware store then you would not have to worry about the LONG PLASTIC FILTER inside the gas tank getting clogged.
Alleyoop

[Steve]

Uhhhh...you know I'm new at this...

If I connect the bottom of the tank directly to the fuel line, where do I connect the vacuum hose?

Maybe it's easier to buy a petcock with only two ports...? But...are we sure I need a new one or is it because the old one has the plastic on it?

Q: Evidently, you think that the fuel flow is OK from the petcock and down to the carb. Therefore you want me to check it coming out of the carb, right?

I was looking at the fuel line today. I'll make it shorter and downward then check the flow from the carb.

< Steve >

[Alleyoop]

If you modify like the picture then you need to get a PETCOCK: The hose from the tank will connect to the petcock, the Vacuum line will connect to the Petcock and then a hose from the petcock to your fuel filter then to the carb.

Right now you do not know if you need a PETCOCK and you can take the PLASTIC filter extension off and mount it again, You already have a VISU FILTER further down. But Also straighten out the fuel line to go DOWN TO THE CARB. Just cut the zip tie holding it to the frame and then take the fuel hose off the carb and cut enough off to make a straight down shot and put the hose back on. You need a PETCOCK like this with 3 ports, the top curved one is for your VACUUM, then one hose from the tank to the input side of the PETCOCK then the other right under the curved vacuum connector goes to your fuel filter then to carb.
Alleyoop

PETCOCK:

[Steve]

Good afternoon!

Anyone have a manual for a BN157QMJ scooter/motor? I have a couple of different GY6 manuals (122pgs, 182pgs, and 200 pages) but they are not specific to my particular BMS Romans 150cc. Of course not. I can't seem to locate a good diagram or picture of my carburetor...

That being said, Alleyoop, is this the CARB DRAIN SCREW you are talking about?



Meanwhile, I reran the fuel line. I cut off about 3 1/2" of it.




Do I pass?

Really appreciate your help - thanks!!

< Steve >

[Alleyoop]

GOod job on the fuel hose now it is going straight down to the carb that will help with fuel flow.

And yes the bottom hose is YOUR CARB BOWL drain hose and it looks like the screw next to it is your DRAIN SCREW if you turn that counter clockwise fuel should come out of the Drain Hose.
Alleyoop

[Steve]

Thanks.

Upon further searching and subsequent analysis....

Yep - that's the drain hose. Only problem was when I turned the screw, the gasoline ended up on top of the engine. So-o-o, now I need to replace a cracked carburetor drain hose. I connected my clear plastic hose to it. It seemed to function well. That means that the fuel spit out; paused (for the float to fill?) and then streamed out again; then repeated each time I tried to crank it up.

It seemed to have more "volume" in its streams than the other tests. Logic would dictate that the only way that could happen is if the fuel line from tank to carb exit is flowing smoothly.

Can I replace the black drain hose inside the coiled wire with the clear polyurethane hose I have?

The real trick is going to be replacing the tension clamp with a new one... ;-)

The next step?

< Steve >

[Alleyoop]

If the drain hose is leaking(split) just replace the hose with any 3/16 diameter hose all the connectors on the carb take a 3/16 id hose. If you have no clamps use zip ties.
Alleyoop

[Steve]

Clamps or zip ties...it's in a heqquva position!

On my chore list is the removal of the petcock and elimination of the rubber portion.

Since the fuel is flowing, do we look at the vacuum system next?

Here is a top view of the whole system:



The cannisters:



What is the function of the cannisters? Can they be tested?

A close-up of the little one:



Is the larger one supposed to be secured in place? Does it matter if it is vertical or horizontal?

What are the two vents(?) for at the bottom?




Thanks for all of your help!

< Steve >