Okay, first off let me introduce myself.  My name is Joe, and this is my very first post.  I just traded my 1990 Ford Bronco for an 86 samurai with a weber carb about two weeks ago.  It has been running great until today.  I started driving to work, and as soon as I got to about 50 mph on the interstate, it started sputtering and jerking.  If I slowed down and put it in 3rd gear, it would run fine.  I pulled off to the shoulder and it seemed to be idling fine.  But as soon as I got back up to about 50 mph it did the same thing, and then died all together.  I coasted to an exit and got off the interstate, and again it started right up.  luckily I was only about 5 miles from home, so I limped it back to my driveway and popped the hood.  There is a fuel filter before the carb, and it looked pretty clogged up with what looked like rust, and when I started the car air bubbles were coming into the filter from below.  I switched out the filter, and now the new filter won't even fill up with fuel, but it will still start.  I took it for a spin around the block, but it's still doing the exact same thing, as soon as it gets up to about 45 or 50, it loses all power, the throttle doesn't do anything, and then it dies.  I'm thinking it's gotta be a leak in the fuel line somewhere?  I took a quick peek down there, and didn't see any leaks, but I wasn't being super thorough.  There also seems to be another fuel filter closer to the fuel tank?  Maybe that could be the problem?  Obviously the lines and probably the tank should be replaced due to the rust in the old filter, but I'm just trying to get it running first. 

So, any ideas?  Thanks in advance for your time and help.
-Joe

Probably the fuel pump, check it out and the diaphragms
probably have little holes in them, change it out and give
it a shot, also check your oil, as it could be leaking into the
crank case too 

Wild

So I replaced both fuel filters and the hose that connects the filter near the tank to the fuel lines, and that seems to have fixed it.  The fuel isn't rust colored anymore, and although I've only taken it above 50 for about a mile, it seems to be running better.  Hopefully that did the trick.  Thanks for your help.

I would be worried also about WHY your fuel was rust colored in the first place.   fix that and you can avoid having a repeat of your issue in the future.

Couldn't the rust in the fuel filter mean your Samurai has a rusty gas tank?

samurai tanks don't rust....they last forever....just kidding. Check your tank because it's probably going to fall apart very soon. I had two filters on my 413K and some dirt still got through and plugged a little screen where the line goes into the carb. You're running a different carb but it might have a similar set-up.