96 pontiac sunrunner bad idle miss bog

[fixkick]

i sure hope it is the FPR.!
but fuel pressures are not right.
and is the most easy to change.

[Barkerman77]

Changed the fpr. Runs great now. I didnt see 60 when i run the pressure test.

[fixkick]

great news.,.
we have rash of them now, this old , all fail how it seams, and MPI is worst case, 16v the poor thing flexes inside ever time you push the throttle pedal.

ive not read the book from GM or Suzuki for 10 years,but... ., I think the book states 58 psi is spec for this shunt test.
its above 50 (pump shunt test) for sure,

the regulator must have over 43psi pressure as input, or it will fail under full engine load,
the pressure from the pump to FPR needs overhead, for when you are at sea-level, and it needs max pressure, to run the car at wide open throttle.
the FPR can provide up to 43psi to all 4 injectors, so the dead head overhead must be way over that amount. (50 for sure, but books show 58)

the shut test or dead head fails?
this test makes sure the pump is ok.
1; 12VDC TO TO PUMP NOT 6V OR 8V. 12V OR MORE, (11.5 WITH WEAK BATTERY)
2: PUMP IMPELLER NOT WORN BAD, (A GUTLESS PUMP worn out )
3: If fails at rail, the filter is packed solid, (but not at filter ,if it is stuck at 58, then the filter is packed and pump is ok)
4: if the hose on top of pump splits, as they love to do 20 years old yeah, fails.
5: wrong gas cap, wrong cap lacking the vacuum breaker, the tank pulls a vacuum and pressure falls. even tank collapse possible see my pump dead page, for photos of that.

nice work, good job and cheers on finding the true culprit.

[fixkick]

the shut test takes 2 persons. engine not running. key on 3 times.
if running, it takes 1 person. but the engine may flood, and cat converter gets real hot and damage can result.
using real fuel pressure gauge , pinch the return line,
on 20 years old that pinch may wreck that 20 year old relic rubber line see at the aft end of FPR


I have nice photo of the FPR here, and that old old line,