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Fuel pressure drop while cranking

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Old Apr 26, 2021 | 10:33 PM
  #1  
Undertow's Avatar
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From: Saskatchewan
Car: 1991 Camaro Z28
Engine: 5.7l TPI
Fuel pressure drop while cranking

I'm experiencing hard cold starts.

Is the fuel pressure supposed to drop while cranking? If not, what causes this?

The Fuel pump primes to about 38 psi, and holds, but drops to 10ish psi when cranking. It seems to do it in relation to the drop in battery voltage. When the car starts, it jumps up to 40-42psi and holds.
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Old Apr 27, 2021 | 07:26 AM
  #2  
Vader's Avatar
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Re: Fuel pressure drop while cranking

You're on it - Fuel pressure is affected by pump voltage. Is the battery voltage dropping below 10V during cranking? Regardless, 10 PSI seems extremely low. I would be wondering about circuit resistance including connectors, relay contacts, and grounds.
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