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Q: Gmc yukon has intermittent long cranks and has a rough idle. Tested fuel pressure at rail. 55psi.

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When I start it the fuel pressure is over 100 psi. Has a rough idle.

My car has 1400000 miles.
My car has an automatic transmission.

Hello. A fuel pressure that is over 100 psi is extreme unless you vehicle has been modified to run that way. When this is the main focus of the problem you are likely having an issue with the fuel pressure regulator. The vehicle will usually have other signs of running rich when this is the case. You can check the condition of your spark plugs, and check for excess grey or black smoke. Both are signs that there is too much fuel in the system. It is a rather straight forward repair if you are comfortable with working with fuel lines and depressurizing the system. For more help resolving the issue, contact our service department to schedule an appointment.

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