Yes, the Fuel Pump should turn on for about 2 seconds at Key On, before you start the engine. This gets the fuel pressure up to its max pressure for startup. Sometimes the issue with ethanol vehicles is that these systems tend to be more corrosive due to the ethanol(alcohol) content in the fuel system. I know you don't really use the E85 anymore, but GM has a Technical Service Bulletin on a fuel system cleaner they recommend. It sounds like a fuel related issue, especially with the slight surging you mentioned. The fuel system on this vehicle has a fuel pressure regulator and a check valve in the gas tank and if there is a little bit of corrosion going on, there might be a little bit of fuel pressure leaking back down and that's why it will stumble for a second and then clear up. Also, if there are no codes set, I would recommend doing the fuel system cleaning service. They have the TSB (technical service bulletin) up for a reason. So, there must be other vehicles experiencing this same issue.
With you having to do a key on a couple of times before it starts, that would indicate fuel pressure is not building up to where it should at the first key on fuel system prime. Unfortunately, flex fuel vehicles are prone to these issues more. Thats why the fuel system components are built with different materials.
If you wanted to do some testing on the fuel system, you can attach a fuel pressure gauge on the fuel rail port and see if the pressure is below spec at Key On. You can watch the fuel pressure with just the Key On and see if its pressure is staying up where it should be. The fuel filter is built into the fuel pump module on these so it's not serviceable without taking the fuel pump out. But I would try the cleaner the manufacturer recommends first, and if you're still having issues, then it would be time to do some diagnostics on the fuel system.
If there is some other reason for the issue, a code will eventually set, giving better direction as to what may be happening.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Wednesday, June 1st, 2022 AT 3:51 PM
