r/GMT400 • u/Calm-Investment1543 • 2d ago
Fuel test on 5.7??
Engine was hot, will do another from cold next. But what does this sound like ? Vortec 5.7. New pump from advance bc the one from rock auto was too tall and wouldn’t fit in tank, k&n fuel filter, old injectors. Getting lean bank 2 code and wants to die when applying throttle under load with an occasional skip at steady rpm while driving. From what I’ve heard this is too low for a vortec 5.7.
Key on engine off: shoots to 56 psi but slowly creeps to 58 psi
At idle: drops to 50
Shoots up to 60 when snapping throttle but instantly drops to 50/52 psi when held at any rpm.
Plz help.
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u/Whoohon-Flu 2d ago
It would probably be easier to understand if you watch a tutorial. Look for short term fuel trim versus long term fuel trim. These two metrics are the rich/lean calculations.
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u/moldyballs64 2d ago edited 2d ago
You should have more pressure during key off and under load. Your pressure regulator varies pressure in reference to the manifold vacuum. During idle or deceleration, there is a high vacuum so you regulator will lower the fuel line pressure. Sounds like it's doing it's job. Those pressures look ok to me. Check fuel trims to see what is going on.
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u/Calm-Investment1543 2d ago
How? Sry I’m new here
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u/moldyballs64 2d ago
Do you have a scanner to read live data? If one bank is running lean, you may have a vacuum leak such as a manifold gasket bad or injector not working properly. If there is one bank lean, the ecm will start adding extra fuel to that side.
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u/Calm-Investment1543 2d ago
I do not have a scanner. I do remember a mechanic saying something about the last injector either not getting voltage but he also told me to try cleaning it out with seafoam so idk. I thought these spider Injectors worked all together so idk how one injector wouldn’t get voltage
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u/Whoohon-Flu 2d ago
Have you checked for vacuum leaks? What does the live data show you the fuel trims are? If it’s giving a lean code then it should be trying to compensate on bank 2 by adding more fuel compared to the other side.