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By Zack Coles
2016 Silverado 1500 5.3L 6- speed RWD. Approx 105k at failure. See "Shudder: Root Cause (1)..."https ://www.gm-trucks.com/forums/topic/249007-shudder-root-cause-1-at-higher-mileage/ for issues with tach bouncing and shuddering.
Occasionally get cold start code, in L.A. area, usu while in a hilly terrain in early morning. Tried injector cleaner and new spark (at some back-alley shop), seemed to help for 5-7k, but it came back and more frequent. Eventually had a fleet shop look at it, followed GM service guide and checked for coolant leak (none) then replaced injectors- I don't have a lot of downtime, so I wanted to get ahead of this issue. No Cold Start codes but less than 1k later, went into limp mode (Low Fuel Pressure code, I believe), and eventually had to be towed (wouldn't start that day but fired right up the next morning in the shop). Had this truck since 30k, and no notable issues.
Mechanics found that the high-pressure pump (fuel injector pump) was missing a bolt head and there was a gap at the pump mounting. Looking at the bolt, it appears to have been over-torqued (threads near shoulder were wore down), but I haven't had issues for over 70k. Either previous owner had shudder/trans issues and mis-diagnosed as misfire, or bolts are inclined for early failure (lots of rough freeway, like L.A., last 50k). Either way new gasket and bolts resolved that issue.
Long time lurker who finally created an account. Y'all have been a wealth of info and I really appreciate it.
I have a 2001 Tahoe LT Autoride with the 5.3. My father-in-law bought it new and I bought it from him when he upgraded to a 2019 Tahoe Premier. I've been going through the Tahoe since buying it from him. It was always maintained at the dealer and serviced at every interval.
The issue I am having now is a hard start when cold. It takes at least 2 cranks to get it started in the morning or after a long period of not driving.
I have searched the forums and found some help but no threads with results. Here is what I have done so far to remedy the issue.
-New fuel filter
-New fuel pump
-Techron in tank (one bottle so far)
I have a new fuel pressure regulator coming and will swap that next but the telltale signs of failure aren't there (gas leaking through vacuum line).
The truck had one other issue that has since been fixed. It would overheat (on the gauge) on hot days mainly at low speeds and belch coolant when turned off. I ended up replacing the fan clutch, coolant temp sensor, expansion tank, thermostat, and expansion tank cap.
Any advice would be hugely appreciated!
1997 5.7 Vortec intermittent slow start revisited.
I have a 1997 Express with a 5.7 Vortec and the CSFI system. It has 130k miles.
It is hard to start after sitting. If I pulse each of the fuel injectors with an injector tester then it starts right up. Problem description is mostly in next post. The test procedure that makes it start is in the third post.
2000 Suburban 5.3L. I'm having problems with the injector circuit for cylinder 3 in my car. I removed the connector on the injector and verified that it's getting power (constant 12V when key in ON position and 14V when engine is running). When a test light was put on the ground terminal it illuminated but didn't pulse. When I looked at the voltage though, it was bouncing all over between 0 and 14V. I turned the car off and noticed the ground terminal had 1.7 kOhms resistance to ground when the engine is off. Thought that was funny as it shouldn't be connected to ground when the car is off and if there was a short, the resistance should be 0. I traced the wiring and didn't see anything wrong. I then found a diagram for the ECM connectors, located the terminal for the cylinder 3 injector (ironically terminal #3) and found the same 1.7 kOhm resistance to ground at this terminal. This was the terminal on the actual ECM not the wiring harness.
1. Is this sufficient evidence that the ECM is bad?
2. Can I just go to a junkyard and pull an ECM out of another 2000 Suburban with the 5.3L and put it into my car with no problems?
3. If not, does anybody have experience with flashmastersecm.com? Judging from ebay, they look reputable.
By Cory G
So I ride a 18 Sierra 1500 with the 5.3L and keep getting gas in my oil, my high pressure fuel pump let go in March of 2019 (40000kms ish) and was the first time I got gas in the oil, they replaced it and it was good until late December of 2019, I drove 800 kms to home, parked at the restaurant and went to go home and got a bunch of codes, saying that bank was to lean, bank 1 to rich, bank 2 to lean, bank 2 to rich and a open circuit fault code. The truck was in limp mode but got it to the dealership, they found a short to a relay for the hp fuel pump and my crank case filled with gas (same as the last time but now the truck at 69000kms) they tested the O2’s, fuel injectors, injector cycles and such, they all passed the test so they figured the hp fuel pump went, so they replaced it. I then drove not even 3000kms and my truck was doing 33L/100kms downhill at 104km/h, no codes or engine lights. Checked the oil and it was over filled and smelled of gas, brought into the dealership and they said the Intake tube after the MAF was loose causing the engine to over fuel, now not even 2000kms (3 weeks) into the dealership “fixing” the issue, my oil is over filled and smells strong like gasoline. Any ideas on what the issue could be? I don’t want to keep paying for an oil change every 2-3000kms and 100$ deductible for my extended warranty. I know it’s not healthy for the engine and GM Canada won’t do anything about it.. Any ideas as to what the issue might be would be awesome, thanks
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