Clyde65

I have a walbro fuel pump ( model 393?) for my 2005 4.8l, converted it to a 02 intake and fuel rails etc. now, the truck runs but it seams to have little power, when I check the fuel pump it reads about 50psi at idle, the needle jumps around too, could this be a bad pump? I was told these engines need 55-62 PSI fuel pressure, help is very much appreciated.

Clyde65

GlennNo50

That pump appears to be a lower pressure pump. I saw one site that rated it at 45psi, 155lph. It appears to be popular for a lot of 4cylinder turbo cars and stockish fordV8's wich use a lower pressure than the LS series chevy motors. You would be much better ff with the 392.

ericwilloughby

There is something else wrong there. Need more information. Is it a 393? External or in-tank? Either way the 395 is the only pump that delivers less than 90 psi. At reasonalbe flow levels of course.