Fuel Starvation and Adding a fuel Pump

jmer1234 · Post by **jmer1234** » Tue Apr 23, 2013 4:35 pm

So there was an earlier thread with folks having their scooters stall as the fuel tanks got low. I have been experiencing this effect when I get below 1/2 - 1/3 of tank. When I stall, I immediately pop off the engine cowl, and see that the fuel filter is mostly empty. Wait a minute and I can start the scooter back up and maybe travel a couple blocks before it stalls again. Initially we thought it might be vapor lock (though I had my doubts) so the dealer drilled a small hole in my gas cap. This did not fix the issue.

I am getting ready to take it back in for round two. I am wondering if a fuel pump might help. Does anybody have any experience with the pumps listed on the SIP site, e.g.
http://www.sip-scootershop.com/en/produ ... +_98840000

JohnKiniston · Post by **JohnKiniston** » Tue Apr 23, 2013 5:12 pm

Does it make a difference if you use the Reserve setting on your Fuel tap vs Main? It could just be a problem with your fuel tap.

Check your hose routing as well, a kink could cause problems.

jmer1234 · Post by **jmer1234** » Tue Apr 23, 2013 6:13 pm

No, the fuel tap doesn't make a difference. In fact, this issue has been getting worse over the year I have had the scooter. Originally, it would start to stall as soon as the gauge hit the red. Most folks have a few miles in reserve once they engage the fuel tap. I have never had more than a couple blocks, so I am thinking it is the same issue, just getting worse.

No kink in tHe hose. I thought of that.

JohnKiniston · Post by **JohnKiniston** » Tue Apr 23, 2013 6:27 pm

Odd. If it were my bike I think I'd replace the fuel tap and see if that helped before I went to the trouble of hooking up a pump. You are either going to have to find a electric pump and tie it into a keyed circuit or setup a vacuum operated pump like the one you linked to but I'm not sure where you would get the vacuum source.

The carburetor is almost directly under the tank, it shouldn't require a pump to get fuel to it.

I thought I had a problem with lack of fuel on my bike but it turned out to be a bad ignition wire & plug boot. It stalled out like the bikes that were vapor locking so I put a drilled gas cap on it briefly before finding the source of my problem.

BuddyRaton · Post by **BuddyRaton** » Tue Apr 23, 2013 6:56 pm

The first thing I would do is check for any crimps in the fuel line. I would then order a fuel tap rebuild kit or try a fast flow fuel tap but these are usually only needed for heavily modified motors.

jmer1234 · Post by **jmer1234** » Tue Apr 23, 2013 8:09 pm

The fastflow tap was what I was actually looking up whenI came across the fuel pumps. I wondered about the vacuum source, leading me to wanting to see if anybody else had experience/opinion on the matter.

jmer1234 · Post by **jmer1234** » Tue Apr 23, 2013 8:16 pm

If I were to get a fast flow fuel tap, would this be the one to get? It lists Vespa PX as one of the compatible scooters.

http://www.sip-scootershop.com/en/produ ... r_15878000

JohnKiniston · Post by **JohnKiniston** » Tue Apr 23, 2013 8:36 pm

It lists the LML Star which is the original branding for Stella.

Now it does say 2T not 4T so there is a possibility it won't fit. I think the tap looks the same on my 4T bike as my 2T bike but I've not compared the two directly.

Maybe call Scooterworks and get a price for a stock fuel tap.

jmer1234 · Post by **jmer1234** » Tue Apr 23, 2013 8:46 pm

The only fuel tap listed on Scooterworks (no sediment bowl) states "fits all tanks after 1960" so I would assume the sip tap is similar. They are roughly the same price. What kills me is the $22 removal tool that basically looks like a wrench stuck on the end of a coat hanger.