Community Q&A Question: new motor swap in my 1990 mustang .... having trouble getting smooth idile

Asking About: Mustang Holley Adjustable Fuel Pressure Regulator (86-93) 5.0


0

new motor swap in my 1990 mustang .... having trouble getting smooth idile

how does the adjustment work on this fuel pressure regulator... came on the motor I just installed.. trick flow street burner top end kit.. has f 303 cam. BBK 255 fuel pump,, all new parts
from Palmetto |

2
With the engine idling and the vacuum line removed and plugged off, screwing in on the adjustment raises fuel pressure and screwing out lowers fuel pressure. You want to shoot for 38-40psi. Once you reconnect the vaccum line, the fuel pressure will drop and this is normal.

Of course, the idle will never be totally smooth with the F303 cam, but I'm thinking you are referring to a surge (wildly fluctuating RPM), not just the lope. Once fuel pressure is set, set your timing to 14° as a baseline if you're running 93 octane(check out our youtube video on the how-to). Next, set your idle. With the engine at operating temp, kill the motor. Unplug the IAC and start the car. If it will not idle on its own, adjust the throttle blade stop screw until the engine will idle steadily at 700-800 rpm. Kill the engine and plug the IAC back in. Set your TPS voltage, refer to our youtube video on how to do this. Restart the engine and let it idle for a minute or two. Then turn on the A/C (if equipped) and allow to idle another minute or two. Then take the car on a 10 mile cruise with plenty of stop and go situations. After this, the idle should be relearned and the surge should be dramatically reduced or eliminated.
from Hewitt |


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  • Mustang Holley Adjustable Fuel Pressure Regulator (86-93) 5.0
    Holley Adjustable Fuel Pressure Regulator (86-93) 5.0
    #LRS-9968HLY
    4 stars (1) $99.99
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