454 Vortec Runs Poorly... (With FP readings)

[BratRod]

Another dreaded Vortec fuel pressure thread... Yeah, yeah. If this was CSFI I wouldn't be asking but I've never dealt with the big motor so here goes.

Truck does not accelerate worth a damn. I'm getting about 8mpg, which is less concerning. Does not have a hot start or cold start issue.

The question is spark or fuel...

Fuel pressure test results are as follows:

KOEO initial: 40psi (if I cycle the key several times I can get it up to 48)

Bleed off test: Does not drop at all. Actually raises presumably from the heat. Gets up to 50 after a few min.

KOER: 38PSI

Steady 2500 idle: 34PSI

Wot while driving drops between 25-30psi

This seems really low to me. But I'm surprised it even starts? Hooked the gauge up to my S10 to make sure the gauge is fine.

I just replaced the fuel filter as a maintenance item. But this problem has existed since I bought the truck.

I'm thinking I'm gonna replace the fuel pump regardless. Just wanted your input.

Thanks in advance

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[Supercharged111]

Yeah I'm pretty sure it's a 4 bar system just like the small block. Check the ground for the pump first, maybe corroded?

 

[BratRod]

New oem pump woke her right up. Ground was also not in the best shape, so I took care of that.

cheers

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