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  #1 (permalink)  
Old 03-26-2021, 12:10 AM
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Default Fuel pressure

So my coyote gen3 is running actually pretty well (i didn't had it running for long yet though). Everything is seal, no leaks- but i seem to have a problem with the fuel pressure.
I tried to adjust fuel pressure (Ford says 55psi when off- 65psi when running).
Though, when it runs I get about 55 and needle moves when blipping- and when I turn off the engine, the pressure goes down to zero.
Could that be within the tune (not even started the process yet)? The vacuum port i've chose? Evt something with the tank breather?
I tell ya, even though there is no fuel pressure, that engine starts back up within a second.
What could be the problem and what to look into first?
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  #2 (permalink)  
Old 03-27-2021, 09:16 PM
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Nice video. Congrats. I dont have a Coyote as a ref or even know what ecu you are using but the issue of fuel pressure dropping to zero with key off is not a big deal. Most modern fuel injected in-tank fuel pump modules use a check valve on the supply line to keep some residual fuel pressure in the fuel line to reduce engine crank times when the car sits for a few days. It keeps customers happy. Some OEMs even have strategy to prime the fuel pump for a second or two when you unlock the car or open a door. But depending on how you set up your fuel pump system, just turn the ignition to on position for a few seconds to prime the pump and build line pressure before cranking and it should start within 1 revolution everytime. The beauty of fuel injection! Your fuel pressure is important as the engine load increases requiring for fuel. Checking it at idle on jackstands blipping the throttle wont tell you if your fuel supply can keep up with engine demand. Thats what test driving or dyno work will tell you while watching fuel pressure values. Its also not clear how you set up your fuel psi regulator or if its all stock Ford Coyote parts. If you will have a low fuel pressure under heavy engine load you will see it in your air fuel ratio numbers pretty quickly. Enjoy the journey. Here is a good article On Coyote fuel system info
Fuel Pump Flow Test - 5.0 Mustang & Super Fords Magazine
"...some assembly required, ages 8 and up...... well that took longer than expected......

Last edited by kitcarbp; 03-28-2021 at 05:47 AM..
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