1rad280 Posted April 4, 2009 Share Posted April 4, 2009 Ok so my 76 280z fuel pressure is through the roof and Iv been scratching my head because I cant figure out what is causing the problem.Then my nephew set in the driver seat and started the car while I checking the fuel pressure,he desided to turn on the head light and the fuel pressure droped and idle smoothed out. So I had him turn the lights off an the fuel pressure spikes and then rough idle. The alternator puts out 14.2 volts and the battery voltage is 13.2. Any ideas? Quote Link to comment Share on other sites More sharing options...
woldson Posted April 4, 2009 Share Posted April 4, 2009 Odd, mabe the voltage drop is causing the fuel pump to "slow" down? In which case it can be cloged lines, filter or regulator?? What is output of alt, before and after head lights? What happens if you load the electrical even more? Quote Link to comment Share on other sites More sharing options...
chrism Posted April 4, 2009 Share Posted April 4, 2009 Does the fuel pump ever turn off after you turn on the ignition or does it stay running? This is without starting the car. Quote Link to comment Share on other sites More sharing options...
1rad280 Posted April 5, 2009 Author Share Posted April 5, 2009 none of the lines ar clogged I have checked all of them I have tried 2 fuel pressure regulators and the same thing happens I even have a after market fpr. I have a ground wire that goes to the fuel pump that dont look so hot,so im redoing that.But I dont see how that could cause this problem unless its back feeding and causing the pump to work harder. The pump runs and gets voltage only when the engine is running. The voltage from the alternator is round 14.4 and with the headlights on about 13.8. Could the ecm cause this ?? Quote Link to comment Share on other sites More sharing options...
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