C15 acert upgraded fuel transfer pump question

When I bought mine two years ago it did not.

 

no you have to buy it separate>

 

Dumb question here. But what does the upgraded spring do on the pump and do I have one on my 02 6nz? Like I said I'm new to this cat power stuff and praise you guys who have the knowledge

 

stronger stiffer spring. holds the bypass closed better! raising fuel pressure. check fuel pressure before anything. if below 90lbs. then you may have the weaker spring. if your trans pump has a allen head fitting on the side, then this spring will work. if it's the regular bolt head you have the old style pump with the narrower spring. that one you just shim the spring. but be careful you dont loose the pin and valve piston when you take the spring out. the allen head style just has the valve piston in it. but like i said check your fuel pressure first around 100lbs is the best. at high idle. (1700rpm)

 

Ok thx ill check it out also ima send u a pm about a injector question

 

I put one on the first of the year,the pump has been updated to 384-8611, this pump comes with the 339-4983 spring installed. before install pressure at idle 75-76 @ 1900 89-90. after install idle 81-82 @ 1900 99-101. It was an easy driveway install. This was on a 6NZ

 

cant remember size. but if you have the new style make sure the washer fits over the nub on the plug. you may have to drill the center of washer out to do this. but it's a temp fix the weak spring will get weaker after a while. better off getting the stiffer spring. if older pump brass washers that will fit in the end of plug resess.