Fuel issues during tuning
10-10-2014, 08:18 PM
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Fuel issues during tuning Ok so I have a l92 converted to ls3 with all requisite parts minus pistons. Heads are milled .10 and I'm using a tsp 231/236 w/112 cam. Motor is in a 2000 firehawk. I am having problems getting fuel over 5000rpm. My fuel system is a racetronix 255 purple pump hotwired running through an inline filter and stock lines up to holley rails with 1 crossover into stock ls3 injectors. Tuning this thing is proving to be a pain. All the injectors are good. I have a m. fuel gauge and run about 55psi and it looks like it drops to 50psi at wot but the needle bounces around a bit so I can't be 100% sure. Anyone have any ideas? I had this issue before the pump and upgraded the pump with the same results. It's actually worse with the new pump. Tuner can't seem to get the ecu to respond. Please help!
10-10-2014, 08:47 PM
#2
I'm trying to find the same thing. Mine drops from 60 to 30 lbs. at wot. I have the same pump but worked fine a couple of years ago when the car first went on the rollers. I changed the fuel filter and cleaned up the ground stud, it was pretty corroded. I also ran a #8 ground wire back to the relay for the fuel pump. I haven't had a chance to check to see if this has helped. Something else that is happening is my fuel pressure drops right off when I turn the car off. Next thing will be putting an external fuel pressure regulator in place of the in tank one. I've already tried a truck alternator but that made it worse.
10-10-2014, 08:54 PM
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Yeah I run truck coils and alternator. I was thinking the same thing about the afpr but not sure how to turn off the one in the tank yet. I'm scared about blowing up my motor I can't imagine how you feel.
10-14-2014, 08:25 AM
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Push the spring clip off the regulator can be removed.
10-16-2014, 10:41 PM
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Ok so I drove it around again today and the fuel pressure holds at 60 psi in all normal driving and when I go above 50% throttle it drops to 57-58 psi. Is this enough to screw with it? That's anywhere from 50% to 100% throttle and it kinda goes down with the gas pedal. I haven't taken it past 4500 rpm but it seems like that's the most the pressure will drop. Does that sound like a regulator issue or a pump issue?