fuel of woe
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Molto Verboso
px 200, lxv 125
Joined: 14 Aug 2012
Posts: 1078
Location: Glasgow
Mon Dec 07, 2020 7:35 am quote
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
Ossessionato
1980 P200E , 2005 Stella 177
Joined: 20 Jul 2018
Posts: 2586
Location: Staten Island, NY
Mon Dec 07, 2020 8:01 am quote
try a new fuel tap.
Molto Verboso
px 200, lxv 125
Joined: 14 Aug 2012
Posts: 1078
Location: Glasgow
Mon Dec 07, 2020 8:20 am quote
It had a new "fast flow" fitted

should the fuel go through the pipe just with gravity?
Moderator
VNB VSC VBC VSX
Joined: 28 May 2008
Posts: 4626
Location: Hustletown, TX
Mon Dec 07, 2020 8:39 am quote
Yes
Ossessionato
1980 P200E , 2005 Stella 177
Joined: 20 Jul 2018
Posts: 2586
Location: Staten Island, NY
Mon Dec 07, 2020 8:43 am quote
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!
Molto Verboso
px 200, lxv 125
Joined: 14 Aug 2012
Posts: 1078
Location: Glasgow
Mon Dec 07, 2020 9:13 am quote
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
Ossessionato
1980 P200E , 2005 Stella 177
Joined: 20 Jul 2018
Posts: 2586
Location: Staten Island, NY
Mon Dec 07, 2020 9:17 am quote
maybe you cut the fuel line too long and it breaks the gravity vacuum going to carb.
Ossessionato
Joined: 24 Jan 2008
Posts: 2004
Location: Santa Margarita,Ca.
Mon Dec 07, 2020 9:27 am quote
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.
Molto Verboso
px 200, lxv 125
Joined: 14 Aug 2012
Posts: 1078
Location: Glasgow
Mon Dec 07, 2020 9:34 am quote
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
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1588
Location: UK (South East)
Mon Dec 07, 2020 9:47 am quote
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
Member
Vespa T5 251, Lambretta GP200
Joined: 27 Jul 2019
Posts: 23
Location: Leeds, England
Mon Dec 07, 2020 2:53 pm quote
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.
Molto Verboso
79 P200E, 62 Allstate, 2008 Stella
Joined: 11 Jan 2006
Posts: 1946
Location: Florence, OR
Mon Dec 07, 2020 3:07 pm quote
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...
Molto Verboso
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 1979
Location: california
Mon Dec 07, 2020 4:32 pm quote
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!
Molto Verboso
px 200, lxv 125
Joined: 14 Aug 2012
Posts: 1078
Location: Glasgow
Thu Dec 10, 2020 2:52 am quote
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.
Member
1965 Vespa VBB
Joined: 20 Apr 2020
Posts: 32
Location: NYC
Thu Dec 10, 2020 11:48 am quote
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.
Hooked
1972 Vespa GTR, 1963 Lambretta LI 125
Joined: 05 Nov 2018
Posts: 153
Location: Halifax, England
Thu Dec 10, 2020 11:50 am quote
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.
Enthusiast
GS-150 VS4
Joined: 04 Feb 2020
Posts: 83
Location: Vallejo, CA
Thu Dec 10, 2020 6:09 pm quote
Sounds to me like a clogged tank cap vent hole might be suspect too.
Molto Verboso
px 200, lxv 125
Joined: 14 Aug 2012
Posts: 1078
Location: Glasgow
Fri Dec 18, 2020 7:05 am quote
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
Molto Verboso
px 200, lxv 125
Joined: 14 Aug 2012
Posts: 1078
Location: Glasgow
Tue Jan 05, 2021 8:36 am quote
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
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