Fuel Problems - when guage gets in the red

[Guest]

My '83 850 seems to have some kind of fuel starvation problem that shows up when the guage gets down to about the red zone, but while there should still be plenty of fuel left (based on capacity and mpg). It will gradually lose power or surge, and eventually die. Changing to "Reserve" helps, but the problem sometimes still persists until I refill the tank, then it's gone.

I've learned to deal with it just by switching to Reserve when the guage hits the red, or when I hit about 100 miles on the trip meter, but I'm reluctant to try and go too far on a tank. Neither one of my previous two GSs did this, and I could run them down to the "E" before I ever switched to Reserve.

The guy I bought the bike from (original owner) had the fuelcock rebuilt or replaced as part of prepping it for sale, so I wonder if that has something to do with the problem. Anyone know what's wrong?

[MinnesotaTim]

Are you sure of how much is in the tank when the gauge is in the red? I've learned over the past couple of years that fuel gauges can be quite inaccurate even when working correctly. Appearently designing the gauges and float mechanisms can be tricky due to tank geometries.

- Tim

[Guy]

Sounds like the petcock is partially blocked. When the tank is fairly full there will be more pressure/better fuel flow. I never take PO's claims at face value unless they can be verified. Strip and clean the petcock yourself - a half hour job, then you'll know for sure. You can also adjust the float arm in the tank to read more accurately if necessary.

[JMHJ]

Thanks. I'll put that on my list of stuff to go over early this summer. I'm sure actual fuel level isn't the problem, since mid-30s on the mpg and problems at 100 miles translates to about a 3-gallon tank or less.

[DimitriT]

Take a flashlight and look around in the tank. Maybe you'll find a tube full of $100 bills.

Seriously, though. You need to empty out the tank and take out the petcock. There's a screen in there which may have gotten clogged up due to someone storing the bike full of fuel in the past. It's possible the screen is only clogged to the reserve depth.

[JMHJ]

Yeah that sounds real possible. I do see rust inside the tank, too. I got some mild hesitating tonight at 60mph, with just over 100 miles since my last fillup, and with Reserve selected. I filled it up and it was fine again.