Walbro setting's and why??

[Koenigturbo]

I just installed a Walbro pump:
I read some where here, that you set your presure it at 35 thru 38 with vaccum line on and 40- 42 with the vaccum line off.
I would like to know about a couple of things please:
( Not doubting anyone, just wanting to know)

I think stock is 35 thru 38 p.s.i , with vaccum line off but how did 40 tru 42 came about?? How was this number formulated? Is this because of larger injectors? Isn't evreyone's set up a little different? Yes, I do have 550 injectors. What did I miss, what don't I understand.
Also I read here that the gauge should read 20 p.s.i after shutting down for five mins. Mine goes right to zero after shut off


Thanks

 

[IRACEMYCOPCAR]

I just installed a Walbro pump:
I read some where here, that you set your presure it at 35 thru 38 with vaccum line on and 40- 42 with the vaccum line off.
I would like to know about a couple of things please:
( Not doubting anyone, just wanting to know)

I think stock is 35 thru 38 p.s.i , with vaccum line off but how did 40 tru 42 came about?? How was this number formulated? Is this because of larger injectors? Isn't evreyone's set up a little different? Yes, I do have 550 injectors. What did I miss, what don't I understand.
Also I read here that the gauge should read 20 p.s.i after shutting down for five mins. Mine goes right to zero after shut off


Thanks

40-42psi is the base pressure with the vacuum line OFF, this is the stock setting. the vacuum changes the fuel pressure and can fluctuate so you set the base with the vacuum OFF, once you put the vacuum line back ON it will probably drop to around 35-38psi depending on the amount of vacuum,the vacuum reduces the fuel pressure at idle because its not needed, once the engine is revved or boosting and not pulling vacuum the fuel pressure rises to the level(base 40-42psi) that you set it.

This setting has nothing at all to do with what fuel pump you are using, it is the stock baseline fuel pressure setting and would be the same with the stock pump/walbro/MKIV denso etc...

Now you can adjust it while tuning for larger injectors etc... if you need to add or pull fuel out.

 

[GrimJack]

Do you have a mechanical or electronic gauge? A mechanical one will continue to display the pressure after shutoff, an electronic one will not.

 

[Koenigturbo]

Do you have a mechanical or electronic gauge? A mechanical one will continue to display the pressure after shutoff, an electronic one will not.

Mechanical,... mines goes to zero after I shut off,..why? Is it because I don't have a "J" tube??

also I read the tech support page, at Aeromotive they are saying the liqiud filled gauges are in accurate when temperture changes.
here's the link you guys may want read it...I find it interesting, scroll down to the last article.
http://www.aeromotiveinc.com/tb.php?id=69