Modern Vespa

Looking for some info
My px200 has been giving no end of grief.

Finally got it running....then it stopped

I discovered that it was getting no fuel when I rebuilt the carb
OK tank out again.
I replaced the fuel line with a clear one and noticed no fuel was coming from the tank to the carb.

I took the line off the carb still no fuel flowed out
I got fuel when I blew into the tank

So my question is, should the fuel get to the carb just with gravity?

cheers

try a new fuel tap.

It had a new "fast flow" fitted

should the fuel go through the pipe just with gravity?

Yes

are you turning the fuel petcock knob straight up thinking it is on open with reserve to full right.. and you bought a fast flow fuel tap that doesn't have a reserve position? Try turning the petcock knob all the way right.

Just shooting in the dark now to see if it is something simple. Apologize if this is too basic and simple but sometimes we just overlook things like that!

The fuel tap is meant to be on when its in the full right position. But even when the pipe is disconnected from the carb and I shake tank the fuel just sits about two inches in the pipe.

like I said the only way I have managed to get fuel through it was to blow it through (made a nice black ring round my mouth I didn't notice)

I'm thinking it could be a faulty fuel tap....total pain

thanks for the info

maybe you cut the fuel line too long and it breaks the gravity vacuum going to carb.

In my experience with the fast flow fuel tap. Works with small frames where the hose can be routed in a direct downward slope to the carb. On a large frame the hose routing requires a low point in the hose prior to heading upwards towards the carb. Without the vent tube as per the stock tap, airlock occurs in the hose whenever an air bubble is introduced, IE running low on fuel/ reserve.

Well just now there is a dirty great big air bubble!

I will blow more fuel though it till it comes out the end then re attach and see what happens

Thanks guys

One of my BGM FF fuel taps was assembled incorrectly, so that ON was actually OFF. I had to take it apart, turn the internal bit round, then put it back together again. It worked fine after that

I tested my BGM FF fuel tap yesterday before fitting. Off is off, On is .5L per minute and Res gives 1L per minute. I have a fuel gauge on the T5 so it is safe to say I will only use OFF and RES.

There also may be some leftover casting from when it was made in the holes.

If you have the fuel tank out you might want to take off the front plate and look at the holes that the fuel goes through.

Mine were 1/2 covered with excess of when it was made. I put a drill bit in by hand and cleaned up the fluff in there...

Looks like these guys have flagged it for you.
Should it flow with gravity - yes.
Most likely some junk in the tap - or a misaligned gasket that is cutting off flow.
My best guess...
Perhaps disassemble - blow out - and you will discover what ever has clogged /blocked it.
Let us know!

Well rain was off yesterday so manged to get the other scoot and junk out the shed so I could get to it.

took the fuel pipe off the carb, leaned the tank round fuel cap (don't want to go around looking like Bluto, lesson learned!)

Blew into the tank, fuel stared to flow. on the reserve position fuel flowed at half the rate as the on position. Let the fuel spill for a bit, then switched to off.

reconnected to carb and fired up. Huge cloud of smoke (will worry about later)

scoot ran for a few min then died.

Lifted tank dirty, great big air bubble in pipe. By dirty great big read 95%. Fuel only in the first 2" from the tank had fuel.

This is doing my box in.

Honestly, seems like you sucked up some crud into that new tap that was left in the tank. You should pull and service the petcock. They are easy to do and clean. I can typically save 1/2 original petcocks I come across, and the other half it is almost always the rubber valve backer that is toast.

Have you got enough fuel in the tank?

If so try blowing back up the fuel pipe as this may dislodge any crud blocking any fuel lines. You should hear bubbling back into the tank. Try this in different positions on the petcock valve.

Failing that remove valve, strip and ensure all fuel ways are clear, or get another valve.

Sounds to me like a clogged tank cap vent hole might be suspect too.

Ok so I now have fuel getting to the carb

Now the little git wont start. (as the sticker on it states "built by c**ts")
Can't get to it because it's been raining for days

hopefully get a chance at the weekend

think I have found the culprit

filled with fuel, blew the fuel through the pipe and tightened the banjo nut, scoot started

next day no fuel in tank, big puddle underneath scoot.
So I'm thinking new gasket for the banjo nut.

the joys