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2018 Silverado 5.3 with instant and violent stalls down the highway

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Hey guys. Having hell with the 2018 Silverado. Truck has been in and out of the shop for months and it seems they just keep throwing parts at it. I work 9 hours from home and pretty much in the middle of nowhere.  So this is getting very frustrating and a tad scary with this issue happening.  You can be cruising at highway speeds for 3-4 hours when the truck will start stalling on and off. Its very violent feeling when it does. If you hurry and get off of the gas, it will resume down the highway usually. But lately when the problems start, they will not go away. First time it started doing it. It was happening at about 70mph. Had codes read and everything pointed to the fuel pump. On my 9 hour drive back home. The issues started happening. But then the trans started slipping as well. Eventually tranny went out about 3 hours from home. Had it replaced. Figured that was the issue and the codes were just junk. Well the next month on my way back home. Issue started happening again. Once again the truck broke down about 3 hours from home. Same exact spot actually LoL. And no I don't take that route home anymore. Well the fuel pump quit working. Had it replaced. Next trip down to work. CEL came back on again with P2635 "Low fuel performance" and P2101 "Throttle actuator position performance". Well eventually got it back home. Dealership replaced throttle body. Figured it was fixed until today. Drove 9 hours to work and during the last 30 mins. The violent stalling came back again. And also while sitting in traffic. It would idle rough and then die. Takes about 5 attempts to start before it starts. Runs fine for about 4-5 mins and will do the same thing again. Can someone please tell me what is going on with this turd??? Im tired of getting towed back home.  

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Fuel pressure test.  So long as the low and high side pressure sensors are operating correctly, someone should be able to test the pressures on the low side (before the high pressure) with scanner or a physical gauge, and the high side via scan tool.


DTC P2635

Fuel Pump Flow Performance




#PIP5427B: Diagnostic tips for SES light with DTCs P2635, U0074 and/or U18A2 set - (Mar 6, 2019)

Subject: Diagnostic tips for SES light with DTCs P2635, U0074 and/or U18A2 set

Involved Region or Country

North America

Additional Options (RPO)

L83 L86 LV3


SES Lamp illuminated, DTCs P2635, U0074 and/or U18A2 set

It may be found that actual fuel pressure (low pressure system) will be reading substantially higher than desired fuel pressure.


Loss of communication between Engine Control Module and Fuel Pump Control Module.


Follow published diagnostics for any communication DTCs set (U0074 would take priority over U18A2 if both set) before addressing DTC P2635.

If DTC P2635 is not resolved by correcting the communication DTCs, only then should SI diagnostics be followed for DTC P2635.

It has been found that a communication issue between the FPCM and ECM can potentially induce DTC P2635 and result in pressure differential between actual and desired fuel system pressures.

If the actual fuel pressure is substantially higher than desired (10 psi / 70 kPa or more), replacement of the fuel pump control module or fuel system components typically will not resolve this issue.

If the actual fuel pressure is substantially lower than desired (10 psi / 70 kPa or more), this PI would NOT apply. It would be recommended to follow SI diagnostics and any related PIs / TSBs.



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I will take this to the dealership when I get back home. 


Today, disconnected the batt again. Cleared the codes. And it drives just fine like it always does. But I know it will eventually come back. Such a pain. Truck had a new eng installed at 65k. New transmission at 73k. Fuel pump at 89k. And a throttle body just last week. Can anyone say Lemon??? Last Chevy I will buy!!

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