2006 Honda reflex runs out of gas early

[Maddog]

Owned this scoot two years, and burned lots of fuel. Twice now it's run out of gas and the subsequent fill up tells me it's still got over a gallon in the tank, shit I can see fuel in the tank.
It's probably got the typical vacuum feed petcock, but I'm expecting to see some debris on the pick up screen.
Oddly, this scoot never sits, it's my daily driver.
After it "runs out of fuel" I fill it up with 2gal and it runs great! The pisser is it holds 3.2 gal.
I've run 3.1 gal out of it before!
Anyone seen this before? I'll be wrenching on it in the morning, and hope it gets me home tonight.

[kz1000st]

Crud on the screen on the petcock. Once cleaned you'll get full volume again.

[Maddog]

I tore that thing down this AM. Shit there is a lot plastic before you can remove the gas tank. The tank was pristine, no debris, no water and no rust. All fuel lines looked good and the filter was clear.
This pick up system uses an open ended metal tube that is routed to the rear of the tank. The delivery is an electric pump, that draws through an external filter, then the metal tube at the bottom rear of the tank.
I removed the sending unit to get the best access, the tube looks good, blowing compressed air through it confirms that it's not clogged.
I cannot find a cause for failure to deliver the last gallon of fuel. Upon reinstalling the empty tank, I only added 1/2 gallon fuel. Test running it and checking fuel delivery from the electric pump, all seems normal?
Fully reassembled and topped off fuel, headed to work 20 mi highway travel each way. Got to work OK! Must be some intermittan gremlins at work here. Hmmmmmm.

[bandito2]

If you had to unplug the power to the fuel pump, I just wonder if it may have had an intermittent bad connection. (one of those hard to find gremlins) And plugging it back in made the connection good again. Sounds like a possibility. The carb could have been temporarily blocked. No vacuum feed petcock as you see it has an electric fuel pump. And yes... the removal of all that plastic to get to the fuel tank AND the fuel filter is a common gripe when it needs to be accessed. Some owners add extra length to the fuel filter line and move it to a more accessible spot.

It seems gremlins don't like being exposed to daylight. Funny, but often going through the noise and motions of removing covers, unplugging items, removing parts, finding nothing wrong and then putting it all back together again seems to chase the gremlins away... This, from experience and tales from others.

[novaraptor]

Possible plugged vent on the fuel cap. Have you tried opening the cap and running it?

[Maddog]

Yes, I did try the cap. Both times I did remove the cap to physically see the fuel level. The only remedy seemed to be adding fuel. I'm thinking that adding fuel was just a coincidence, cause it was not low on fuel and any cause of low level has been eliminated.
Recently I removed fuel down to the level when it last failed, bottled one gallon under the seat as a reserve. Rode the shit out of it till it ran dry. Found that you can add 3.2gal after running out, just as the specification sheet said.
Guessing that the electrical intermittan issue will be a continuing deal.

[Ebuddy]

I wonder if the fuel pump isn't just a hair under the pressure that it's supposed to be. In this case, perhaps the extra weight/pressure of the fuel in the tank is giving it just enough to keep going, but when the volume gets low enough, it crosses over the minimum pressure threshold.

[Maddog]

While I had the tank exposed, I ran the engine and removed the fuel line to the carb. With minimal fuel in the tank, the electric pump provided plenty of fuel to the carb to run the bike. I again am guessing the pump intermittently loses power and the float bowl runs dry. My multiple attempts to restart it must justle a bad connection or component into operating again.
I ride this scoot to work almost every day. It's only stopped 2 times, and these have been in the past 3 weeks.
The bike sits outside in the rain while I'm at work, if this continues I'll start running down the electrical wiring to try to find it. But for now it's 70mph cruise 20 miles one way every day. It's been a great ride for the last two years.
Bandito, great idea on that rear car tire. 20k and loads of tread left. Thanks!