This is topic 68 Mustang: Fluctuating fuel pressure & idle in forum Tech Talk at Northern California Ford Owners .
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Posted by SilverLX351 (Member # 3207) on
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I just got my friends 68 mustang going, it has an 88 5.0 motor and a Tremec 3550. It has MSD coil, box, and distributor. It has a Holley blue pump with regulator set to 6psi. I set the idle to 800rpm and test drove it. After 5 minutes of driving the idle went to 500rpm and 4 psi on the fuel pressure guage, so I put them back up and it did the same thing again....ANY ideas?? EVERYTHING is new, so could something be defective?
thanks
Posted by PunkINa5.SLOW (Member # 10) on
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If it has been sitting awhile could be debris
Posted by Fostang (Member # 3752) on
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umm? what kind of carb? what does it have? 800 rpm why(I can see why if you have major performance parts)
Posted by SilverLX351 (Member # 3207) on
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i dont know why 800rpm, it will idle lower no problem. it has been sitting for 3 months. Any other ideas?
thanks
Posted by Fostang (Member # 3752) on
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I would idle mine at 550 rpm with edel carb, perfomer intake, performer cam, timing at 12, full advance 36, fuel pressure at 5.5 psi, (edelbrocks are not ment for more than 5.5 psi.)
Posted by SilverLX351 (Member # 3207) on
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I set the fuel pressure to 5 psi, but cant set the idle lower then 700 or the motor shakes too much because of the cam. Thats beside the point though, why does the fuel pressure keep on going up and down on its own?? this morning it was down to 2 psi, we set it to 5 and now its up to 6.5?? Please help any way you can!!
thanks
Posted by PunkINa5.SLOW (Member # 10) on
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Dude you probably have debris in the fuel lines.
IF not that then make sure the voltage is not fluctuating to the power lead on the fuel pump itself.
Holley blue pumps along with their regulators are usually pretty sturdy
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