1990 Chevy 5.7L TBI Surges At Idle And Has No Power?

Question

fuel press is 9 lbs key on, also running. not findind any bad vacuum hoses. when i disconnect the vacuum line to the map sensor the engine runs normal but still no power. disconnect the harness to the map, no change. replaced map sensor no change. new cap and rotor no change. when i manually turn the TPS sensor the engine tries to die. disconnect the TPS no change. disconnect the iac, no change. any ideas????? thanks in advance.

Answer 1

Replace the fuel filter and put a gas guage on it to see if there is enough fuel pressure.. if anything below 40psi, replace the fuel pump if already replaced the filter.

Answer 2

Did this start out of no where. Or did you just buy this. It could be a high RPM cam.

Answer 3

my dads truck did the same@187k miles, 2 months ago

it was the fuel pump (he has a 1992; 5.7l tbi also

did the same @150k miles, 4 years ago, and it was the heads

Answer 4

wow where were you a week ago? had the same thing ended up being a fuel pump! same thing good pressure just bad idle and no power! unpluged the map and it ran like a dream!! i thought 4 sure that it was the map! NOPE! replaced it and it still ran like c**p! cant  explain y unpluging the map made it run good but the pump did it and it runs great!