quick fpr question

[exzercist]

i adjusted my fpr to the base pressure which is 44 psi with the vacum hose off. i did it by putting power to the pump check wire. my question is when i have the car on the base pressure is i think higher than the base pressure, is this normal? thats the only way to correctly set the pressure right?

 

[brute]

You set the FPR to the desired pressure with the vacuum hose DISCONNECTED (like it appears you have done) then reconnect it. When you fire it up, the vacuum hose being connected will make the gauge read higher than without it.

 

[steve]

When you fire it up, the vacuum hose being connected will make the gauge read higher than without it.

What?

Your were correct that base fuel pressure is when the hose is disconnected but the fuel pressure with the engine running is going to be = base pressre + reference pressure. Vacuum is negative pressure so with the engine running at idle the fuel pressure will be less than base. 18 in hg vacuum is almost -9 psi.

Steve

 

[exzercist]

so does that mean at idle it should be around 35 psi?

 

[steve]

With the hose on assuming 18 in hg vacuum at idle and the stock base pressure.
fp = 43 + (-8.8) = 34.2 psi

Your numbers will depend on what your running as base pressure and what sort of vacuum you get at idle. Since your running a 44 psi base 35 psi at idle would be in the right ballpark.

Steve

 

[exzercist]

got my car running for the first time for summer and my fuel pressure was set at 44 psi last year and it idles at 36 psi but i think the computer still needs to learn what the fuel maps are.