Measured the fuel rail pressure. Key on, engine off, I get 40 PSI, which seems fine. Engine idling, I get 26 PSI, which intuitively seems low. I can't find a spec. Should it be higher?
- posted
16 years ago
Mercury 5.0L fuel pressure
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- posted
16 years ago
Fuel pressure is controlled by engine vacuum. Higher vacuum = lower fuel pressure. This can happen if timing is overly avanced resulting in high vacuum. Normal readings in most
5.0L vehicles is 32-35 at idle - all accessories off. A good service manul has a vacuum/pressure relationship chart.Lugnut