10 psi difference between static and non-static?

[dpok69]

I have a thrasher 92 chip and pressure is supposed to be at 45 psi. I ran like that for a while but my car was running a lil rich. So i backed it down to 39 psi. I never had a knock problem according to my SM2.

Today I was adjusting my fuel pressure up for a new mease downpipe. I adjusted it to 32 psi with vacuum hose on. When i take my hose off it is 42 psi. I though there was only supposed to be a 5psi difference between static and non static.

Do i have a vacuum leak somewhere?

 

[DavzGN]

A TR with good vacuum with have 17-19 inches of vacuum at idle. 2 inches of vacuum is about the same as -1 lb of boost. So if you have 18 inches of vacuum at idle, your fuel pressure will be 9 lbs less than static pressure.

HTH
David
87GN

 

[spining 6]

i'm glad you asked.

mine does the same thing about 10 lbs. differnce.

 

[TurboDave]

Yup, it's all related to the vacuum you're pulling, the difference will be the vacuum you're making. Assuming of course, a good accurate fuel pressure gauge or vacuum gauge.

As has been shown, if your car is idling at around 17" of vacuum (pretty typical) you'll see about an 8 1/2# difference in fuel pressure.

You obviosly have fairly high vacuum of close to 20"