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goodwrench9124
goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3432
Experience:  Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
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2000 chevy tahoe 4wd 5.3 liter idles at 50psi fuel pressure.

Customer Question

2000 chevy tahoe 4wd 5.3 liter idles at 50psi fuel pressure. cylinder 3 misfire code detected. the complaint is chugging, lack of power on acceleration intermittently. fuel pump does not hold fuel pressure in line after vehicle is turned off. drops to 20 psi.
Submitted: 8 years ago.
Category: Chevy
Expert:  Steve replied 8 years ago.
How did the spark plug look for that cylinder?

Steve
Customer: replied 8 years ago.
hey Steve thanks for the reply. Acctually i have not pulled it yet. It was dark and i was missing my spark plug sockets. my friend replace them a year and a half ago. what do you think about throttle body cleaning?
Expert:  Steve replied 8 years ago.
General maintainence Is a good thing to get out of the way before you iagnose a problem like this.

Steve
Customer: replied 8 years ago.
#3 spark plug was replaced. problem still exists.
Expert:  Steve replied 8 years ago.
was the spark plug black and carbon fouled?

If so you cauld have a leaking injector.

You should ohms check the injector to fond out if the electromagnet is functioning properly.

Steve
Expert:  Steve replied 8 years ago.
Also disconnect the fuel pressure regulator to see if the fuel pressure rises.

Steve
Expert:  goodwrench9124 replied 8 years ago.
Hello, just helping out. fuel pressure is too low. here is the spec.

379-427 kPa (55-62 psi)

 

more than likely you have a weak fuel pump. bringing up the fuel presure will probably take care of your missfire and low power.

 

A lean condition may result from the fuel pressure being below (55 psi). A lean condition may cause Driveability conditions associated with lean conditions can include hard starting, hesitation, poor driveability, lack of power, surging, and misfiring.

 

A fuel system that drops more than (2 psi) in 10 minutes after being relieved to (10 psi) indicates a leaking fuel pump check valve.

 

Fuel pressure that drops-off during acceleration, cruise, or hard cornering may cause a lean condition. A lean condition can cause a loss of power, surging, or misfire. You can diagnose a lean condition using a scan tool. If an extremely lean condition occurs, the heated oxygen sensorss will stop toggling. The heated oxygen sensor output voltages will drop below 300 mV. The fuel injector pulse width will increase

 

goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3432
Experience: Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
goodwrench9124 and 5 other Chevy Specialists are ready to help you
Expert:  Steve replied 8 years ago.
Thanks for the assist.

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