Sign of bad pump? or PSI reg?

[Tonatom]

1986 Turbo Z, T2 conv not sure if it has stock 87 or 88 injectors.

Car runs perfectly fine until 3.5k RPM then starts bucking and stuttering, (Pretty much as soon as I hit power band) happens until I shift out of it. Happens in every gear at the same RPM range. Builds Boost perfectly fine, I can hold the car through the bucking and it will build to 12-14 Psi but not instantly. So I have ruled out Vac problem.

I have checked the HEP connections too, I thought if it was a HEP prob it would prob happen at all RPM ranges.

So I am wondering if it is a Fuel Pump or Fuel PSI Prob, I have spare Reg and Spare pump in a separate car.

What is the Fuel PSI Supposed to be at Idle (on 87 and 88 injectors)?


Thanks for any help.

[phantomrt]

Maybe neither. When there is an insufficient fuel delivery issue, bucking/jerking doesn't really occur. I'll blame this problem on a weak ignition system. I'm not there to see it myself though, so I am shooting in the twilight.

[NAJ]

Static rail pressure is 53-57 psi.With the engine running rail pressure will drop 1 psi for every 2" hg applied to the FPR.In boost fuel pressure shoiuld rise 1 psi for each lb. of boost.
Until you run basic diagnostics it is all a guessing game.