Had my 50k scheduled maintenance done about 400mi. ago and two days ago the “check engine” light came on. Figured I did not tighten the gas cap and would keep an eye on things. The next morning when I started the truck it idled rough and so I went straight to the dealership. They hook it up to the computer and said that the air intake gasket needed to be replaced for $500+. After changing the gasket and the truck still not running right they now say that they need to replace the fuel pump. At 50k mi??? This does not sound right. It ran fine when I brought it in for the 50k maintenance. Could this be right?
A simple fuel pressure test will tell you if the fuel pump is bad. They should last 150k or so, but there are always exceptions. Do not have the pump replaced until the pressure is tested.
Another thing to check out on these is the fuel pressure regulator. If you have the hood open, it sits on the right side of the motor. you may have to take off the plastic “Vortec” shield. There is a vacuum line that goes straight to the intake manifold. After running the vehicle, pull that vacuum line off the regulator. If fuel comes out of the line, you found your problem. There is a thin diaphragm inside the regulator is prone to fail. When it does, you are sucking raw fuel into the intake and essentially flooding your motor.
Aside from that, there are dozens of things that could cause your problem. Plugs, wires, injectors, throttle body, you name it. I just gave you a few things that are typical of that truck. Try these out and let me know what you come up with.
They hook it up to the computer and said that the air intake gasket needed to be replaced for $500+
Wow, that’s quite the diagnostic leap of faith!
After changing the gasket and the truck still not running right they now say that they need to replace the fuel pump
This is their next GUESS but that is completely unnecessary as maximumbob has already pointed out.
For the life of me, I cannot see how these shops make these kind of diagnosis without any diagnostic testing to back it up. They spent $500 of your hard earned (I assume) money chasing a red herring. Ask them for the diagnostic evidence that supports the fuel pump diagnosis and then ask them if they will refund all or most of the money for the improper diagnosis. Bet dollars to donuts they say, Oh, that was bad too, we had to replace it to see the pump issue…
Thanks maximumbob and TwinTurbo. I called the service department first thing in the morning and asked if they had done a fuel pressure test and checked the fuel pressure regulator and they said that they had. They wrote on the invoice " Found P0171 and P0174 stored in ECM. Checked for vacuum leak and found that the intake would leak vacuum when the vehicle was cold but would seal when warm. Test drove after intake gasket replacement and found that the truck would intermittenly hesitate and lose power, almost didn’t make it back to the shop due to no power. Installed fuel pressure guage and found that at times while driving the gauge would drop to 25PSI when should be at or near 60PSI. Tested circuit and found that the fuel pump was going bad."
Maybe I just had some bad luck but I don’t need to be paying $100/hr for labor any longer. Does anybody know a good mechanic in midtown Kansas City, MO?
@HiLow FWIW leaking intake gaskets are a common problem on your truck. And you had all the right symptoms and fault codes.
It sounds like they did perform the diagnosis to confirm the fuel pump and gaskets
FWIW I have replaced plenty of fuel pumps on vehicles less than 10 years old and with less miles than yours.
PLENTY
I am on the 3rd fuel pump on my 2000 silverado, I was told these are a weak spot on alot of gm vehicles.