I have an 89 rs with a 350 HO crate engine and TBI with big injectors and a programmed chip, open element and open exhaust wit o2 sensor. I was running fine until the fuel pump went out which I replaced with a walbro 255 in tank. now it will run fine until I get about 10 miles down the road and it just cuts out. Will not run or idle for a while then will start and idle but not run. It's almost like something heats up like a sensor or something. It did the exact same thing when the fuel pump was going bad but then I could not hear the fuel pump when I turned on the ignition now with the new fuel pump I still hear it come on, yes the new fuel filter is in the right direction. battery , alternator, coil, plugs are fine.

 

the fuel pump fuse is most likely blowing i think its a circuit breaker typ relay.
the fuel pump is most likely drawing too much current and after a while those typ of fuese ie:circuit breakers reset themselves over time. just like window motor fuses.

 

any idea how to fix that? Thanks!

 

yeah get a new fuse that has a higher amp rating i dont know the specs but the fuse is usually located on the drivers side firewall next to the vacuum booster there should be 2 there one is the fuel pum and i forget what the other one is see if you can fine one that is compatable and swithch it out.