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Gary, ASE Certified Technician
Category: GMC
Satisfied Customers: 17006
Experience:  GCM master tech over 25 years
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Gmc yukon: 2002 gmc yukon xl 5.3 flex fuel no codes engine

Customer Question

2002 gmc yukon xl 5.3 flex fuel no codes engine stalls will restart runs for 1 to 2 miles stalls again fuel pressure 45 psi when running 10 psi when stalls changed fuel filter and fuel pump relay
Submitted: 2 years ago.
Category: GMC
Expert:  Gary replied 2 years ago.
I am sorry your having this problemthe fuel pressure will drop down slow to 10 then stall out ?key ON engine OFF what is the fuel pressure reading and will the needle hold on the pressure gauge or drop to 0 within a second or two ?
Customer: replied 2 years ago.

needle holds at 10 psi

Expert:  Gary replied 2 years ago.
with it only being at 10 PSI and a new fuel filter the problem is going to be a weak / bad fuel pumpkey ON engine off it should be 48 - 54 PSI and holdif when the engine is being cranked over or the 2 second prime when you first turn the key ON the grey wire at the pump shows 12 volts and the big black wire is a good ground then replacing the fuel pump should correct this problem you are having
Customer: replied 2 years ago.

but after i crank the engine 1 or 2 times the fuel pressure go back to 45psi and holds for 1 to 10 miles runs fine

Expert:  Gary replied 2 years ago.
then when the pressure drops down it stalls correct ?when the pressure is at 10 when cranking it over see if the grey wire at the fuel pump shows 12 volts and see if the big black shows a good groundif those both check out and it only has 10 PSI there is a fuel pump failure going on
Customer: replied 2 years ago.

yes when pressure start to drop engine start to stall

Expert:  Gary replied 2 years ago.
ok this is going to come down to a bad fuel pump OR the grey wire not showing a full 12 volts when its reading 10 PSI or the big black not a good ground when its at 10 PSIwe have to cut our problem in 1/2if the grey and black wire read good readings like i said when its at 10 PSI then the fuel pump needs to be changedif there is a problem with the grey or black wire let me know as then we go after which signal or reading was wrong when its at 10 PSI