I finaly found the noise, now what !?!

It's a follow up from this thread i started last year

https://www.tacomaworld.com/threads/winter-and-the-1gr-fe.745538/

Well, i finaly found the tapping/ticking noise (not the taco tick).

Short story, the noise started last october when the night became colder. The noise was a tapping/hammer/ticking noise around the driver side under the dash or near the floor. It was intermitent and only heard in the cab. Did a piston pressure test, changed the fuel damper, secured all tube fitting with ty-wrap in the hood, checked the flex plate for crack, checked for engine mount, did a fuel pressure test, fan/clutch inspection, replaced the gasket in the exausth... The noise last only like 30 seconds so troubleshooting was a share of hypothesis and luck if i can say that.

Okay so what's the noise....
Well a month ago after some good off-roading for a camping trip, i started to hear the noise even with 30C weather at cold start and it sounded more and more like my old copper plumbing when i was using my washing machine but very fast. The noise was still intermittent so i started a new routine each morning with the hood open and started probing.

I knew the sound started when the secondary pump (SAI) did is sequence and stop and the fuel trim dropped near -10% negative i think because the added air from the sai and the wideband O2 was reajusting the mix air/fuel ratio, it's been a while since i was looking at the fuel delivery system but even with a new fuel pulsation damper the noise was still there and i don't have any other problem, for a 10 year old truck with more than 140k miles it drive like new.

Last weekend the noise started again and i was ready, i found out that when the fuel trim drop near -10% the return fuel line started to vibrate, sometime it was just a faint pulse, but that day i was able to see the line moving a little, grabbing it by hand was like touching the sound i was hearing in the cab, it lasted 30 sec and the pulse became so faint that i can't tell if it's the fuel or engine vibration. I found out that under the heatsheild near the first catalytic converter driver side there a plastic bracket holding all the line and only a little stud welded on the cabin floor keep that in place, this bracket have some little play in it and i think when off-roading or when temperature get colder, the fuel line/bracket move and create some play and this create the noise where the line vibrate and tap under the floor....

Now what??

I know the fuel regulator keep the rail at 41 psi when running, when the engine is off, the PSI start to drop slowy after like 15 minutes and reach around 32 psi after 45 minutes, so i know it's in the Toyota specification and there are no leak.

The fuel damper is new and nothing changed. The problem is in the return line, i don't know if i need to change the fuel regulator to see if this fix the hammer noise in the return line. It's linked when the injector cut the duty cycle so there probably a increase of pressure in the rail and the regulator doing it's job pulse the fuel in the return line until it stabilise or get hot idk....

It's a 170$ part i don't mind to buy it for "science purpose" but i saw no one changing this part anywhere for a 2nd gen, first gen owner with more miles had a few case where the regulator was ticking and replacing it was the solution, in the GM, Porche, Ford forum they have some pulsation but only when they install bigger injector or new racing pump so it's not my case. I only found a 2006 tsb for the 2TR-FE engine where they changed the fuel line material because of the noise under the floor. Not even related to any regulator or damper or the V6.

So now i can always wedge something between the bracket and the floor to see if this minimise the noise but i need to be careful to not keep moisture and rust the floor panel, or change the regulator to see if it's a cold start only problem when the fuel pressure stabilise in the return line.

I have 2 choice of regulator

2328031060 and 2328031010 the 1060 fit on 2012-2015 the 1010 fit on the

$60 2005-2015 Toyota Tacoma With 4L Right Petrol intake air snorkel kit high performance system compatible kit Replacement black Rotational Molding (2005-2015)

2005-2015, both same price, verified with my vin number. Anyone know the difference ??

Edit : Talked with the service guy at Toyota, The 2328031060 is the number for the 2012-2015 V6, It seem the 2005-2015 year range for the 1010 number is a typo i should be 2005-2011 and it seem that the year of manufacture change the number too, (mine is a 2012 made in 2012) but some 2012 made in 2011 got the 1010 number if you check with the VIN number). Still waiting for the Service guy to see if some pulsating is normal at cold start.


Thanks!!