2012 Isx 2350 475 with codes 4726 and 0559

[ahrenbenjudah]

Ok. Well. I read somewhere that a bad pressure sensor can cause similar issues so I tossed a new one in and also changed the fuel filter even though it had just been serviced before all of this happened.

Now, I have a single code for DPF temp sensor module and that’s it.

Insite reads:

Fuel pump actuator commanded current: 0.00mA
Fuel pump actuator duty cycle: 5%
Fuel pump actuator measured current: 62.5mA
Fuel pump actuator position: open
Fuel rail pressure commanded: 5228
Fuel rail pressure measured: -19 to -36 (it fluctuates)
Fuel rail pressure rationality sensor: -514
Fuel rail pressure rationality sensor voltage: 4.55v
Fuel rail pressure sensor signal voltage: .5v

It will crank but will not start.

[ahrenbenjudah]

Oh. I just got a code 4691: Engine Injector Metering Rail 1 Cranking Pressure-Data Vaud but below normal operating range-moderately severe level.

I’m really starting to wonder if my lift pump crapped the bed.

The first “possible causes” is a malfunctioning fuel lift pump. Even if I couldn’t get cranking pressure, I would think my lift pump would provide the initial pressure to the rail for start up.

[tree98]

Rail pressure is 19-36 what? Psi ? If so that's obviously a big problem. Can you hear the priming pump come on and run for 2 minutes when you turn the key on(engine off)?

[ahrenbenjudah]

Yeah. 19-30ish psi. The lift pump comes on, but doesn’t really sound like my other trucks. It’s hard to describe. Where most of the other trucks just sounds like an electric motor sound, this one has a different sound that I can’t explain correctly. It sounds different.

[tree98]

Sucking air somewhere

[ahrenbenjudah]

I thought about that as well. However, I would think it would be leaking somewhere wouldn't it?

On a side note, I grabbed the fuel filter that I pulled off of it on Friday and looked in side of it. There is detritus in the bottom as well as what appears to be rust. I haven't cut it open to verify what the junk is. The tank itself looks super clean. It's a 100 gallon tank and I can see both pipes and the sending unit as well and everything looks great. Nothing is in the bottom of the tank, nothing is floating, the stand pipes are both unobstructed.

I am confused now more than I was before.

[ahrenbenjudah]

So I finally got back to this thing on Friday after a couple of weeks dealing with other stuff. I inspected the lines from the tanks to the diverter/crossover valve, and from the valve to the davco. Nothing reared its head. Blew air through the lines and they weren't plugged with anything. I pulled the filter out of the davco and confirmed that when the lift pump is whirring, there is no air being drawn in to the davco container.

My next step is testing the lift pump itself and seeing what I find out. I'm waiting for my new pressure gauges with compucheck fittings on them to come in later this week so that will help with some of the other tests.

[Rawze]

(01-25-2022 )ahrenbenjudah Wrote:  ...
Following the Cummins test of blowing air in to the inlet of the head, the plungers both extend. But as soon as I remove air, the rear one sinks back in to the barrel.
...

did you ever fix this problem,?.. those plungers are NOT supposed to sink back down.. not one bit... but spring back and stay up.. indicating they are not leaky.

also, if the guts have more than 8,000 hours on them or 400k miles of use (or if you really donl't know how old they are).. then all the guts (tappets, plungers, barrels, etc.) need replacing to prevent complete engine destruction.

[ahrenbenjudah]

Hey Rawze,

Yes. I replaced the fuel pump head and the barrels, tappets, rollers and plungers completely.

During this I have also replaced the Fuel Rail relief valve, and the fuel pressure sensor.

Also, I just noticed, that in my previous post that the commanded voltage on the actuator looked like this:

Fuel pump actuator commanded current: 0.00mA
Fuel pump actuator duty cycle: 5%
Fuel pump actuator measured current: 62.5mA
Fuel pump actuator position: open

so it was commanding 0ma, but was reading 62.5ma. I'm unsure if that would cause the problem i'm having, but I am attempting to get back on to testing with it today.