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Discussion Starter · #1 ·
Application: '91 Sable 3.8L

My Haynes manual specifies 39 PSI (doesn't say whether static or engine running).

My readings:

Static: 40 PSI
Engine idling: 32 PSI
Engine idling/vacuum supply disconnected: 41 PSI

Leakdown: from 40 PSI to 32 PSI in about 45 minutes

I perceive the 32 PSI to be low and I'm concerned that the system is depressurizing too quickly after shutdown... or are these readings within the realm of reason?

Regards... Mike
 

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Just had a fuel gauge hooked up to the fuel rail at a Ford dealer and was told pressure should stay between 30 and 40 pounds.
Do not mean to disagree with Josh but this is what I was told. Also I have the vulcan.
 

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Josh is 100% correct.
 

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I agree, the fuel pressure is leaking down too quickly. 32 psi is within spec, but on the low side, should be upwards of 35 psi. The high pressure is fine, it can go up to 45 psi without problems.
 

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Discussion Starter · #7 · (Edited)
Hey, thanks for the replies.

I noticed that the o-ring on my pressure tester fitting is pretty rough and that there was a little fuel residue in that area. Gotta go to the o-ring store tomorrow and get that corrected before trying again.

I detect a slight fuel odor in the vacuum supply line, but none in liquid form. The soap test produces no bubbles on the diaphragm vacuum fitting.

The symptoms that prompted me to look at fuel pressure are tip-in hesitation and rough running upon restart after 15-20 minute shutdown. The latter symptom became worse in the past few weeks... I blame it on the winter fuel blend aggravating the problem.

I'll come back and report when I know more.

Regards... Mike
 
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