Extended cranking, fuel system tests.

[lincolnlocker]

You can reset alm the adaptive tables with forscan and basically force a relearn.

Also, not sure why nobody has said anything but low pressure fuel should be 80ish psi all the time.

You have a leak between the tank and lpfp or its worn out or the control valves on the motor are stuck open allowing the low pressure.

If it where me, i would put a new lpfp on it being everything else looks clean in all of your pictures.

And use a good fuel additive every tank.

Cp4.2 might actually have taken some abuse with the low psi fuel going to it.

 

[Tiha]

Also, not sure why nobody has said anything but low pressure fuel should be 80ish psi all the time.

Exactly, I was hoping someone would see that and elaborate on it.

That reading is taken off the high pressure rail. It is not the switch that triggers the LP alarm and puts it in limp mode.
That switch is calibrated to 30K psi. So a little tolerance is understandable. Reading 42 psi on the scanner as opposed to even say 80 psi. The sensor could be off by that much. That is what .02% tolerance

understandable isn't it?

And if my PSI was actually less than 53 then the switch would close and I would get the alarm. So the switch would have to be bad as well.

I found one thread online where the person said his KOEO psi reading was 350. Like on my 2016. He said he replaced the sensor and the new sensor said 0psi. So he put the old sensor back in and kept running it. LOL

and I had thought about just throwing a pump on it but that is a $500 gamble in itself.

When I pinched off the return line the fuel rail pressure went to 96 psi. according to the scan tool. The LPFP is internally regulated at 120 psi. Taken that information and apply it to the ASSUMED variance in the pressure sending unit it made sense that the pump was working properly.

Regulated at 120 but reads 96 psi. 24 psi off.

now add that 24 psi (variance) to the 42 I measure and get 66 psi. Within spec.

To me the logic was sound. Maybe I need to make an adapter and put a manual gauge on it. Yuck, I don't want to.

 

[Tiha]

I ordered a fuel pressure gauge adapter. Be here next week.

Pretty sure I am okay, But now I gotta know for sure.

 

[lincolnlocker]

You're not ok if its still a long crank. Not sure what the specs are but low pressure fuel should be at and stay at 80psi at idle or wot. I can see a drop to 76psi every once in a while but that is rare. When my brothers lpfp pump went out, it was doing exactly what yours is doing. It tripped the low pressure warning like once. Threw on my spare lpfp off my 12 because i thought i had an issue there back when i had it. Fuker holds 82psi all day long now. My turning might be a bit more aggressive than his as his never drops below 80psi.

I told him i wanted to trade it for mine. Lol.. my 15 has 250k on the clock. That 12 pump has like 110k on it. My brothers lpfp tanked at 90k and thats a 15 as well.

 

[Tiha]

I was supposed to have a fuel pressure tester adapter by now but it hasn't even shipped yet.

I tried to build one.

Looks like the upper fitting is a 12mm found a quick connect that works on 1/2" or 12mm. It seems to snap onto the fuel filter just fine.

But the Steel end, 12mm, to make the adapter is currently not available. 1/2" steel is too big to fit into the factory fitting.

So I thought I would just make a hose to snap in place of the return line.

Nope, the other end is like 9/16" or 14mm. I cannot find that quick connect anywhere. 5/8" is available, but that is too big.

What a joke. Sick and tired of amazon and their fake reviews and their fake ship dates.

Amazon says carrier has it. USPS says they have not gotten it yet.

Granted there have been gaps in shipping information before but not like this.

 

[Tiha]

Tried to move the truck last night. Would not start. Now I am pissed.

Was running, pulled return line to try and make my own pressure adapter. Which I failed at. Put line back on because I can't keep waiting on this stupid adapter forever with this thing in my garage.

Now I can't get the fuel system purged. Maybe that is a sign of bad lpfp but online seems to be fairly common thing. Even with brand new LPFP or that and an entire decontamination kit.

With the return line completely off the rail pressure still reads 42 psi. So certainly some inaccuracy there.

Cranking my PSI never increases, which is jumped right up before. I am sure that is because it is air bound.

So Now I need to try and purge the system just to get it running.

The fuel pressure adapter I ordered now finally shipped. says arrives next week. We will see.

When I was doing fuel pressure tests last fall I clamped a hose on the return line and ran it into a bucket. During that test I clamped off the return hose completely to test dead head pressure.
So now that I think back on that. I could have built a gauge adapter and just hose clamped it in place.

Now I don't care, just want to get it running and get it out of the garage so I can get started on other projects I am way behind on.

 

[Tiha]

Well low pressure is 62 psi per maual gage.
Still won't start.

Rail psi not coming up.

Pulled intake again. Pulled flow control valve. Still clean. Pump full of fuel.

Found this.

"quick tip here. The typical failure with cp4 pump is a bad valve seat on the Intake non-return valve (suction valves). We have found that when an injector line is cracked open, and the key turned on to operate the lift pump a good cp4 the fuel will ooze out. In the case of failed suction valves the fuel will poor out and travels about 1.5 to 2 inches up."


I tried it and my fuel definitely shoots into the air a few inches.

According to that my cp4 went bad. Sitting in my garage. Nice.

Can anyone confirm? I am not even sure what to check next.

I unplugged the pressure sensor so it showed 30k rail pressure. Still no start.

 

[Powerstroke Cowboy]

I have seen pickups go.from running to not running in seconds due to a failed hpfp. The one was shut off, started up and maybe backed up 40 feet and it shut of and was done. No hints of failure before.

These things are all but impossible to diagnose over the e-net.

Do you have metal shaving caught in the screen of the metering valve? That's on top of the cp4.