wjmac40

!989 vette, been running great, until yesterday! Was driving highway speed when all of a sudden car started bucking and surgeing. Got off highway and on coast down was smooth
At stop light rpm's fluxed from 5 to 8
on demand of fuel car runs good, however when I reach speed desired the bucking and surging starts, push more on the peddle and it stops
Got home and gunned it up and had all kinds of black smoke
No service light came on , But i tried to get a message anyway and got nothing, Including no code 12
Looked for short or open vacum but saw nothing
Same thing happened this morning

rick lambert

Well, if you did try pulling the codes correctly you should have gotten the code 12. Did you put the paper clip in the top 2 right hand pins...then turn the key to the ON position without starting the car?

Next I would check fuel pressure.