I've got a 1998 carbureted fatboy and when I ride the bike has been shutting down around 65 miles like it has no gas. I look in the tank and there is still a bunch of gas. I then turn the petcock to reserve and I am able to keep riding. I am able to go farther than 65 if I begin riding a full tank on RESERVE. Is it bad to run the bike this way? My dad thinks it's because the bike hasn't run in 2 years and there is dirt in the tank. My bike recently left the shop and they went through it and did the fluids.

 

I would check the petcock.... sounds like perhaps the upper portion of the pick-up tube is plugged up....possibly due to sitting around and the gas plugging the screen.

 

You can ride until you run out of gas, if you always use reserve - that is bad! One possibility is that air isn't getting into the tank, as you ride, does the tank hiss as you undo the gas cap? Another possibility is that a PO has replaced your gas tap at some time with one that fits, but isn't quite right. Ride until the fuel level is low, then drain the tank into a suitable container, remove the gas tap and check inside the tank - flush out any muck if necessary. You could also replace the tap with a known good quality one, such as a Pingle, which should give you a more sensible reserve, before you turn to reserve. Also check the balance pipe between your tanks and make sure that is free-flowing.

 

had the machine since new??? if not, then perhaps the petcock was changed and it has a higher stand pipe or maybe yours has a hole in it. pull it out and check, measure height so you can see where fuel level is when running out. the equalizer tube is a good point as was mentioned.

 

WOW! Today the bike shut down at 40 miles!

recently bought it third owner, cap doesn't hiss when undone

 

I’ve got a 1998 Dyna and mine was dying between 1/4 & 1/2 tank left. Would idle and start just fine but when under load it would cough and die. I was on my way to OC bike week and it did it. Filled the tank back up and would run fine. Was able to get the local dealer to remove the petcock and found it clogged up as my tanks inner liner is disintegrating from ethanol/water in the fuel. They cleaned it up for me as they didn’t stock the filter and I continued on with no more problems so far but I’ll probally get the tank relined over the winter.

 

Screens clogged.
If he can restart it in reserve I'll bet it sat with 1/2 a tank and the gas seperated. causing a varnish ring on the lower run position portion of the screen.
Maybe

 

Make sure your tank is venting properly and if you have an in-line fuel filter installed get rid of it.

 

OK---Dumb question here: Are you filling BOTH tanks?
That bike should have about 4.2 gallons capacity between the two tanks.

Check the cap on your left tank--it may be a LH thread, needing to be turned to the left in order to loosen and remove.

Fill the LEFT tank first, cap and then fill the RIGHT tank last.

If you're only "topping off" on fuel, fill the RIGHT tank first and see if the level drops and if so, the fuel is transferring to the left tank.

Some later model bikes (not sure what year it started) were equipped with a vacuum system that opened the fuel flow.

The only other suggestion I have (happened on my cousins '82 Low Rider) is that the fuel tank "nipple" on the RH tank that connects to the rubber cross-over hose may not have bored (I.D) large enough and is not letting fuel transfer quickly enough into the LH tank.

 

Blocked tank crossover line