Even after I pulled my tank and sloshed over a cup of trash (including a dead mouse) out of the tank, I found that out of the blue I would get these "hiccups" as I called them. If I pulled over and let the bus sit for a while, I could get it going again for another while. I've spent up to an hour on the side of the road, though.

My guess was that the trash was getting sucked in enough to create a vacuum. Even though I could get fuel to go through the lines, it wasn't enough.

Here's what finally fixed it:

1. Pulled the tank

2. Poked a nail up into the tube from which gas flows, discovering a tar-like substance in the tube at the bottom of the tank.

3. Had the tank acid washed. (If you do this, bring a sealer with you. I didn't and I could see rust forming by the time I got it home. If you don't have a sealer, bring something that will dry the tank and something else that will oil it...like dry gas and wd-40).

Once I reinstalled it, everything worked like a charm. I run two in-line filters and watch for gas.

***I think the problem is that in these old buses, if they sit for some time, the gas starts turning to shelack (which I've heard it does) and gums up the tube where the gas leaves the tank. The reason it interferes at speed and doesn't appear to do so when you press in the clutch is beyond me.