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Tim Mohr
Category: GM
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05 GMC sirerra cranking time before start up,frp desired

Customer Question

05 GMC sirerra long cranking time before start up,frp desired 5801 , actual is 217 with key on cranking goes from 490, to 1500 psi and finally starts after 8-30 Sec depends if first start or after running awhile, should I check injectors or lift pump
Submitted: 1 year ago.
Category: GM
Expert:  Tim Mohr replied 1 year ago.

Hi, my name is ***** ***** is usually a bad fuel injector returning too much fuel to the tank on start up, it will drop the rail pressure and pressure to all the injectors, have done a return fuel test yet?

Customer: replied 1 year ago.
No, do I need to take off the lines on driver side and put one in a container and take out which relay, and how much is to much fuel
Expert:  Tim Mohr replied 1 year ago.

yes, and then crank it over , the fuel return should be less than 11 ml, if it is any more, then you hav one or more injectors returning too much fuel, if its lower than 11 ml, then suspect the lift pump, another test is to push the black button on top of the lift pump to prime it up before trying to start, if it starts right up then, replace the lift pump,Tim

Expert:  Tim Mohr replied 1 year ago.

most of the time, its a bad injector,Tim