Why do we hear the High Pressure fuel pump during the "cleaning cycle"

Hello, I just upgraded from 2nd gen to 3rd gen and almost had a heart attack the first time I heard the knocking/ticking noise. After some googling it seems to be because of the high pressure fuel pump for the direct injection.

Im trying to wrap my head around how exactly this works. The port injection is supposed to "clean" the valves, if that's the case then why do we hear the DI pump during the cleaning cycle? Shouldn't it just be the port injectors at that point spraying fuel?

 

It's mechanical, its always connected to the cam shaft lobe.

 

the fuel pump is mechanical? So during a cleaning cycle both direct and port injection are spraying fuel?

 

https://youtu.be/_KMyfpop9Fs?si=GvFjnF9Gq4Dj1uuw

 

For thousands of years the wise ones asked:
If nobody is around to hear the high pressure fuel pump cycle, does it really make a sound?

 

I've had my truck since it rolled off the delivery truck at the dealership and I cannot say I have distinctly heard this loud high pressure pump I see frequent posts about.
Either my hearing is just that bad, I have poor timing and never catch it running or having grown up around diesel trucks and tractors my whole life anything less than a 12v Cummins is as quiet as a well oiled sewing machine.

 

I've heard it twice whilst leaning against it having a smoke in the evening several hours after it was driven. I must admit the first time
I heard it I was quite worried about wtf was going on.

 

I've been with my '17 since new and I have never had the pleasure either.

 

The direct injection squirts fuel directly into the cylinders. The cleaning cycle is for the direct injectors, not the intake valves, which port injection covers like you noted.

 

I've had two 3rd gens. 2016 access cab 2wd V6, and now a 2017 TRD OR double cab long bed. The 2016 was relatively quiet during the cleaning cycle operation but it did have a subtle tick almost like an idling diesel (a comforting sound if you ask me).

My 2017 on the other hand chirps fast and loud like an orchestra of sparrows, finches, and titmouse conducting the symphonies of their people. There is no mistaking a faulty high pressure fuel pump when you hear it. Bought the truck at 52K miles. Currently has 83K. I've used non-ethanol 91-O fuel in this truck (ECU tuned) for all but maybe ~7K of the miles I've put on. The only thing that makes my high pressure fuel pump shut up is non-ethanol fuel. The moment ethanol gas hits the tank she starts singing her sweet songs like clockwork.

There are videos out there that demonstrate the issue, but I'd be happy to make my own if anyone is interested.

Toyota issued a TSB for the chirping fuel pump some years ago but it was only good while still in powertrain warranty and I missed out unfortunately. Currently there is a recall for the HPFP if there is fuel leaking out of it. Suggest people take advantage of this if they are having issues with the pump; it is an expensive little part.

 

when i walked by my truck that was parked for some hours i heard the sound of a motor. didn't think anything of it till i got past and realized the sound was the truck. the sound was the area of the left rear wheel.

i opened the cab to see if i had somehow left or turned something on. found nothing.

got ready to crawl under but before i did the noise stopped.

you say its the cleaning cycle. i really don't understand how the pump coming on when the engine is not running cleans anything al all. why would not just regular usage work just as well? same fuel same pump same injectors same truck. just a waste of gas.

 

Read the first page of the Owners Manual. Noted there that the LPFP will do a check cycle while the engine is off. The HPFP is mechanical, geared off of the right cam.

 

I see your 12v, and raise you a detroit diesel. lol

 

i read the owners manual from cover to cover or at least skimmed it. don't know how i missed that unless it just fell through the sieve of my brain.
thanks

 

Here you go.

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