ok. i have here a fb 12a gsl completely stock engine.
Car starts fine, idles perfect, drives normal.

My problem:
When driving, if i reach highways speeds (apprx) 50mph, engine starts to lose power causing it to shutting down. It only does this sometimes, but most of the time it does it. If i down shift when i reach around 20mph, car will regain normal power. It feels like there is a vacuum leak somewhere. Also, gas meter never goes up. it stays below "E". started when engine power loss started happening.
But again, Car starts fine, idles perfect, & drives normal.

 

Have you replaced the fuel filter? Or are you saying that the electrical system causes the power failure?

 

I have not replaced the fuel filter. and it seems it could be an electrical problem down the line but i have no idea honestly. ill change the fuel filter tomorrow and see if it does anything.
hope i can make it to the rotary meet tomorrow in salt lake.

 

Ten bucks says its your fuel filter...

 

Probably, or check for loose connections on spark plug wires, at the ignitors, and at the coils. Also, make sure the battery connections are nice and clean/tight...

If you make it to the meet, let someone with lots of experience drive the car. Nothing beats sitting in the seat to get a feel for this type of issue...

 

I've been having the same problem, whips around the suburbs but when I try to get it to highway it dies (and tends not to want to come back to life if it floods) I knew the gas was bad and the carb needed a rebuild. So I checked the gas in the lines, no joke, dark yellow like a German beer. I got this car last august and had ran it for a little while to try and burn out the gas (the fuel gauge is broken making this an annoying process) So the gas in it is probably like 2+ years old, maybe more as the guy who had it before me didn't drive it and the guy who had it before him left it in storage for 10 years. So yeah, check the fuel your carb is getting and make sure it's nice and clear.

 

thanks guys. i changed the oil yesterday and it now drives high speeds on the freeway normally. but acceleration power is decreased a bit. ill be rebuilding the carb, and putting a whole new fuel system and other goodies in when i rebuild the engine this year. But after the meet, its time for the tear down. Today will be the last ride for months to come. Ill post some pics of the Utah Meet.

WISH ME LUCK GUYS!