Thread: Engine Vacuum and FPRs
03-19-2014, 04:54 PM #1
Engine Vacuum and FPRs
If anyone is having issues with the vacuum playing with your fuel pressure and making it harder to tune i found a solution while installing my new fuel system on Grand Cherokee SRT. available from mcmaster carr, it will screw into your boost source and only allow 1psi or greater to affect fuel pressure, no vacuum
03-19-2014, 05:04 PM #2
Good find. I just had to switch to static because the vacuum was sending my afr's into the high 14's.
03-19-2014, 05:08 PM #3
you can use a check valve and not get any vaccume
03-19-2014, 07:07 PM #4
Cant you just install a fitting on the charger side of the throttle blade?
Then its boost only referance.
03-19-2014, 07:30 PM #5
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03-19-2014, 08:02 PM #6
Stupid question....if the fitting is on opposite side of the throttle plate how is this vacuum created?
03-19-2014, 08:08 PM #7
At idle the motor sucks air creating a vacuum due to the throttle blade being mostly closed.
03-19-2014, 08:11 PM #8
ahh..don't know why that light bulb didn't go off on that one. Thanks..this was good info since a rrfpr is in the near future.
03-19-2014, 08:14 PM #9
I have always had good luck running them from the intake, but every setup is different, and may require this boost only reference.
03-19-2014, 08:25 PM #10
If you were to install a fitting for boost only reference where on opposite side of throttle plate would the preferred location be? Looking at the throttle body it sure doesn't look like there's any room where the sc hose ends to the plate.
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