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Gary, ASE Certified Technician
Category: GMC
Satisfied Customers: 17036
Experience:  GCM master tech over 25 years
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1996 GMC truck 5.7l engine. I have tested the fuel pressure

Customer Question

1996 GMC truck 5.7l engine. I have tested the fuel pressure system it at 52 psi and have change the throttle position sensor. but the truck when you call for full throttle the engine stalls. and back fires
Submitted: 1 year ago.
Category: GMC
Expert:  Gary replied 1 year ago.

I am sorry for the long wait

what is the fuel pressure key ON engine OFF and will the pressure hold or drop down fast within a second or two ?

Customer: replied 1 year ago.
With key on it at 50psi then slowly drop to 20psi with key on
Expert:  Gary replied 1 year ago.

is the fuel filter new ?

the spec is 56 - 62 key ON engine off

if the fuel filter is new you have a weak fuel pump not making enough pressure

you will need to correct the fuel pressure to spec next

the odds are with correct fuel pressure the truck will run fine

Customer: replied 1 year ago.
OK I will get a new pump
Expert:  Gary replied 1 year ago.

and a new fuel filter if it has not been changed yet

we have to correct that pressure first

you can always get me back through this post any time for FREE with any follow up with this question anytime as i do not get credit for my work until you rate us here