jspaeth
10-13-2009, 07:26 PM
I have had this ongoing problem....95% of the time, my fuel pressure at idle is 35 psi (with vacuum plugged in)
5% of the time, it reads about 30 psi.
Things it is NOT:
1) Vacuum related----a vacuum leak at idle would cause the f.p. to go UP
2) Bad voltage at the pump
a) At 35 psi, checked voltage between power wire to pump and ground wire, got 12.6 volts.....checked between power wire and chassis, also got 12.6 volts
b) Did the same thing when the idle f.p. was down at 30 psi, got SAME voltage readings.
What else could it be? Why would the fuel pressure every so often go down like 3-4 psi at idle?
Possible causes:
1) Fuel filter? (but I feel like this would cause larger f.p. drops, and less predictable ones....mine are ALWAYS 3-4 psi drop).
2) Pump intermittingly "underperforming".....again, the voltage drop across the pump seems okay in both cases, and the pressure drop is predictably 3-4 psi.
Any comments would be helpful, especially in light of the fact that I recently discovered that the voltage to the pump is good in BOTH conditions.
Thank you
P.S.....I was checking the voltage in the near-dark, and somehow my ground pin on my multimeter touched the clip i had clipped to the power wire.....and the car went off....the fuel pump 15A fuse blew....
Is there any reason to suspect that any other electrical damage occurred? The car drives fine, I am just paranoid.
5% of the time, it reads about 30 psi.
Things it is NOT:
1) Vacuum related----a vacuum leak at idle would cause the f.p. to go UP
2) Bad voltage at the pump
a) At 35 psi, checked voltage between power wire to pump and ground wire, got 12.6 volts.....checked between power wire and chassis, also got 12.6 volts
b) Did the same thing when the idle f.p. was down at 30 psi, got SAME voltage readings.
What else could it be? Why would the fuel pressure every so often go down like 3-4 psi at idle?
Possible causes:
1) Fuel filter? (but I feel like this would cause larger f.p. drops, and less predictable ones....mine are ALWAYS 3-4 psi drop).
2) Pump intermittingly "underperforming".....again, the voltage drop across the pump seems okay in both cases, and the pressure drop is predictably 3-4 psi.
Any comments would be helpful, especially in light of the fact that I recently discovered that the voltage to the pump is good in BOTH conditions.
Thank you
P.S.....I was checking the voltage in the near-dark, and somehow my ground pin on my multimeter touched the clip i had clipped to the power wire.....and the car went off....the fuel pump 15A fuse blew....
Is there any reason to suspect that any other electrical damage occurred? The car drives fine, I am just paranoid.