Fuel pressure / fuel gauge

GOLDROADS · 11-12-2008

PART 1 ( fuel pressure )
this ia a stock 5.0 HO . i have 30 psi of fuel at idle . it will increase to 40 psi if i remove the vacuum from the fuel regulator and it does go back to 30 psi when vacuum is replaced . if i close/ pinch of the fuel return from fuel regulator to the tank my fuel pressure does not increase ( i beleive it should ). with the fuel gauge still attached to the fuel line i drive the car and the fuel pressure drops down to 20 psi and lower. this is my problem, under mid to heavy acceloration i get popping / backfire out of the throttle body . i noticed it is only when the fuel pressure is low. by the way this is with a new fuel pump . ( i think i have a defective fuel pump ) . and i beleive the fuel pressure should rise under acceloration. can someone confirm this?
PART 2 ( fuel guage )
the gauge did not ( always read full ) . i got a boneyard sending unit and it tested 12 ohms full and 74 ohms empty ( i beleive this to be the correct specs ). once the tank was back up and filled with gas, the dash gauge reads closer to empty with the more gas i put in. can anyone help here?
IS IT POSIABLE THE TWO HAVE ANYTHING RELATED IN A SHORTING OUT / LOSE OF POWER KIND OF WAY?

GOLDROADS · 11-17-2008

PART 1 ( fuel pressure )
this ia a stock 5.0 HO . i have 30 psi of fuel at idle . it will increase to 40 psi if i remove the vacuum from the fuel regulator and it does go back to 30 psi when vacuum is replaced . if i close/ pinch of the fuel return from fuel regulator to the tank my fuel pressure does not increase ( i beleive it should ). with the fuel gauge still attached to the fuel line i drive the car and the fuel pressure drops down to 20 psi and lower. this is my problem, under mid to heavy acceloration i get popping / backfire out of the throttle body . i noticed it is only when the fuel pressure is low. by the way this is with a new fuel pump . ( i think i have a defective fuel pump ) . and i beleive the fuel pressure should rise under acceloration. can someone confirm this?

PART 2 ( fuel guage )
the gauge did not ( always read full ) . i got a boneyard sending unit and it tested 12 ohms full and 74 ohms empty ( i beleive this to be the correct specs ). once the tank was back up and filled with gas, the dash gauge reads closer to empty with the more gas i put in. can anyone help here?

IS IT POSIABLE THE TWO HAVE ANYTHING RELATED IN A SHORTING OUT / LOSE OF POWER KIND OF WAY?

dakine858 · 11-17-2008

Quote:

Originally Posted by GOLDROADS

PART 1 ( fuel pressure )
this ia a stock 5.0 HO . i have 30 psi of fuel at idle . it will increase to 40 psi if i remove the vacuum from the fuel regulator and it does go back to 30 psi when vacuum is replaced . if i close/ pinch of the fuel return from fuel regulator to the tank my fuel pressure does not increase ( i beleive it should ). with the fuel gauge still attached to the fuel line i drive the car and the fuel pressure drops down to 20 psi and lower. this is my problem, under mid to heavy acceloration i get popping / backfire out of the throttle body . i noticed it is only when the fuel pressure is low. by the way this is with a new fuel pump . ( i think i have a defective fuel pump ) . and i beleive the fuel pressure should rise under acceloration. can someone confirm this?

PART 2 ( fuel guage )
the gauge did not ( always read full ) . i got a boneyard sending unit and it tested 12 ohms full and 74 ohms empty ( i beleive this to be the correct specs ). once the tank was back up and filled with gas, the dash gauge reads closer to empty with the more gas i put in. can anyone help here?

IS IT POSIABLE THE TWO HAVE ANYTHING RELATED IN A SHORTING OUT / LOSE OF POWER KIND OF WAY?

When was the last time you changed your fuel filter? Also, you should be reading 10 ohms full, 73 ohms empty.

It's possible that the two are related in that you might have some faulty wiring on the sending unit which is screwing up your gauge reading and not sending enough power to the pump to properly charge the fuel lines.

GOLDROADS · 11-17-2008

i did change the filter along with the pump, and thanks for the input. i wll get to trying a few things this week if i have time.

chris12398 · 11-22-2008

for the most part, your stock regulator isnt adjustable. It should rise maybe 5psi under accel. And you wouldnt know unless you have an electrical guage. Change out your regulator. There would be a popping noise if there was a leak at the tank anywhere (Sending Unit, Pump, Lines. I had a bad Sending Unit and there was a small leak, going around corners it would lean out an pop if I had it on the throttle at all. Replace the regulator and if you get a chance change the filter too.