lly fuel pressure issue

[razorryan10]

looking for some more qualified eyes and brains

truck is having low fuel pressure doesnt set codes but its lower then what is being commanded, if i go into efilive and force it to full rail the actual pressure doesnt even move but desired goes 160mpa
things i have done are injectors,two different pumps, 2 new lbz fpr (is tuned for them),new rail pressure sensor, new dual fueler controller from wehrli fab

some codes that i have had are p0100 which i have seem to fix and then a p0090 has popped up
i attached some logs at idle cause dont like driving it, it has died sitting at red lights why dont kno, no codes nothing but it fires right back up
im running out of things to test and change

 

[2004LB7]

First test is do a fuel return rate test of the CP3, relief valve and all the injectors

Report back with the numbers you get

 

[razorryan10]

has new injectors now did it with stock and 60%, has new 100% same problem
cp3 pumps are good they have been changed also all checked in spec x2 same problem
relief valve is a race valve its not leaking pass (had that happen to buddys truck. first thing i checked)
does it with multiple tunes (moto ops,my tunes, and marks
is it possible that the lift pump isnt suppling enough fuel if any at all and its just sucking the line dry
lift pump is not pumping any more or just every little, its running but i just havnt checked the pressure its putting out

i know everything says injectors or pumps i have eliminated those 3 times now
its like ecm has no control over pumps, ecm tells it to do this but it doesnt go down the line to pumps

 

[2004LB7]

What pressure/vacuum do you have on the supply to the CP3? Put a gauge on it. Use the schrader valve by the alternator

 

[shakenfake]

Never
Ever
Works

 

[razorryan10]

what would make my frp reg flow to be at 23k mm3/s and frp current 1.2ma at idle when it should be around 6-8k mm3/s at like 1.35ma current

logs from 2 years ago show thats the biggest difference before having the issues

 

[razorryan10]

got back to it
lift pump pressure- 10psi
all injector return rates are within spec(2ml)
both pumps (.5oz very little/belt pump was 1oz )
reg duty cycle is at 27%
reg flow 20k-22k at 1235ma

1 pump returning that much at idle shouldnt make the pressure drop so bad to make the motor surge
valley pump should be able to hold it at idle, driving down the road not a chance

 

[razorryan10]

this thread can be removed truck is fixed

 

[Bdsankey]

Can you report what the fix was? That could possibly help someone in the future.

 

[2004LB7]

this thread can be removed truck is fixed

We typically don't close threads unless they go off the rails. It's sometimes helpful when someone has the same issue and wants to pick it back up without repeating everything all over again. And as Brad mentioned, what was the fix?

 

[razorryan10]

not 100% sure but swapped to new ecu loaded tunes and fuel pressure is doing what it is being told and holding rail pressure, reg flow is super low(8k-9K and current is up around 1.35-1.4ma now and changes
so maybe shorted out something in ecu before fixing bad harness wiring