2011 5.3 L hard to start but not always

bepierce59 · July 9, 2016

In Dec' 14 I purchased a 2011 5.3L Silverado with 79k miles. I believe the truck had spent its entire life in Michigan. We moved to Kansas in Jul '15. The truck had about 85k by then. At this time the truck began experiencing hard starts. Generally the first time I start the truck it fires right up. The next time I start the truck (same day) it will crank longer but eventually start. The truck runs great once it has started. Engine temp or outside temperature does not seem to matter. I have tried several suggestions to fix the problem over the last year but no luck. First I ran the tank near empty and put in a fresh tank. I did the same once again with some fuel injector cleaner. I have cleaned the mass air flow sensor a few times. The truck has al K&N cold air intake (had it when I bought it) so I have washed and oiled the filter (followed by cleaning the mass air flow sensor a few more times). I have also changed the spark plugs. I have tried the various starting methods such as turning the key to "on" so the fuel pump can do its thing then turning the key to start. My foot is never on the gas peddle and I release the key as soon as I turn it to start. So, with all of the above the problem persist. More of an annoyance than anything as the truck always starts and runs great. Ready to challenge the local Chevy dealer with the problem but hoping for any additional ideas anyone may have that will save me some bucks. Thanks!

CapitalTruck · July 10, 2016

Try the key to "on" a couple of times before the start. Also, just for kicks, I would clean the throttle body. If the butterfly doesn't close all the way due to carbon buildup all sorts of cookey stuff can happen. With key on (engine off) have somebody step on the throttle to open butterfly and spray it out with throttle body cleaner (like CRC stuff, not old school carb cleaner) and wipe out the carbon. Finally, what is more of a possibility is fuel injector leak down. There are tests that can be done for this.

https://www.injectorrx.com/leaking-fuel-injectors/

That's are my $0.02 No guarantees, but that is what I would be thinking...

bepierce59 · July 10, 2016

Thanks for the suggestions. I will give them a try.

MaverickZ71 · July 11, 2016

Welcome to Brownbackistan. If your truck has a flex-fuel engine (will have a badge on the tailgate), you may need to have the alcohol-sensor reset at a GM dealer. Kansas does not require any gas stations to say how much ethanol percentage is in their fuel. Labels at the pumps may be old and inaccurate. There have been some threads on this site in the past dealing with ethanol/fill-ups/alcohol sensors and such. I remember one of them said if you run E85, don't switch back and forth between E85 and gas very much; and that if you get more than 1/4 tank worth of fuel, the system recalculates the ethanol/octane percentage, but it takes almost 7 miles to do it, and if you turn the key off before 7 miles, it does not finish recalculating. Gotta love this new technology. Or not. Good luck, and keep us posted.

bepierce59 · July 11, 2016

Key on and off multiple times prior to start did not help. Still need to check the throttle body although it appeared clean when I last cleaned the mass air flow sensor.

Truck is Flex Fuel so alcohol reset sounds interesting. I have never used E85. Truck was in Michagan for an additional six months after I purchased it and started with no issues. The problem did start once we made the move from Michigan to Kansas. It has been a year now that the truck has been burning Kansas pump gas. I would have thought any computer fuel adjustments due to change in fuel quality/variation would have corrected the problem by now. I will mention the alcohol reset to the dealer should I end up taking it them to fix. Thanks!

CapitalTruck · July 12, 2016

I'm betting on fuel injector leak down, be sure to let us know what the cause/fix was.

bepierce59 · July 15, 2016

So a few days ago I pulled the throttle body off. The inlet side looked pretty clean but the outlet side was dirty. Did not expect it was so dirty as to cause the starting issues but so far I have not had a bad start. It has only been two days and only six starts but I'm keeping my fingers crossed! I will provide an update after a few more days.

Colossus · July 16, 2016

Keep us posted.

bepierce59 · July 19, 2016

All good things come to end. Hard starts returned today. I am thinking the brief improvement may have been from the throttle body recalibrating after I cleaned it? I did bump the butterfly ever so slightly. ThInk it's time to visit the Chevy dealer. I'll ask about the alcohol reset and fuel injector leak down.

bepierce59 · August 3, 2016

I still have not taken the truck to the local dealer for service. I don't drive it all that much and I am hesitant to spend the money for what I expect will be more than one trip to the the dealer (misdiagnosis). I have, however, discovered something new. First start of the day still goes smoothly. Before I do any subsequent starts I turn the key to the on position and then I press the accelerator pedal down about half way and release. I then start the truck. The start is not as smooth as the first start of the day but there is only a slight hesitation before it fires up. I can live with this but still concerned that the underlying problem needs to addressed before something more serious occurs.

MaverickZ71 · August 4, 2016

Since the legislature passed the law letting retailers sell us pretty much anything as fuel without marking what mixture it is, the quality of fuel in Kansas has gone straight to heck. I believe the state checks the volumes at the gas pumps, but not the ethanol mixture percentage or octane rating or that the mandatory minimum-level of detergent additives is present.

You might try running a few bottles of Chevron Techron Fuel System (not fuel injector) cleaner in your next few tanks of fuel and see if that helps any.

Does your truck use any oil? If so, your spark plugs may be fouled and a new set of plugs might help.

On a newer computer-controlled, fuel-injected truck, you shouldn't have to pump the gas pedal before any start--you should be able to just turn the key to start and go.

bepierce59 · August 5, 2016

Truck doesn't burn oil and I have a fresh set of plugs in her. I only press the gas pedal down before starting because it actually helps with the current problem.

I have an appointment next week wth the Chevy dealer. Their first thought, based on what I told them, was the fuel pressure regulator. Hopefully by this time next week the problem will be solved and I will still have money in the bank! I will provide an update.

TheDrunkScotian · August 5, 2016

I would try to look at this in a simple way o suppose. I highly doubt it has anything to do ignition wise, likely fuel related as the dealer said. After the trucks been run you have A. Boosted the pressure in the lines and B warmed the truck up. Maybe you're experiencing some sort of vapor lock? Fuel pressure regulator would make sense. I know a bad fuel tank pressure sensor can make a truck do all sorts of funny things as well. Just my two cents, but honestly, hell if I know.

Keep your stick on the ice

Will

bepierce59 · October 19, 2016

Truck finally fixed! Per my previous post, I took the truck to the local dealer and explained the problem. Their first thought was the fuel pressure regulator on the fuel pump. I had scheduled an appointment but had to cancel. Ultimately I decided to replace the fuel pump myself. Took a while to get the tank low enough on fuel to make removal easier. I dropped the tank and installed a new Delco pump yesterday (great YouTube videos on how to do this). The bad starts are history!

Note that prior to the repair I did discover that turning the key to the on position and fully depressing and releasing the accelerator pedal one time did result in the truck starting with just the slightest hesitation. I'm sure doing this long term would have some negative effects as ultimately I had a bad regulator.

I appreciate all the help with my problem. Hope all these posts will help others!

Cheers!

Colossus · October 20, 2016

did you replace the filter as well while you were in the tank? oh man this brings back memories of people left and right having issues with their GMT-800s with the 5.3L and fuel sending units in the tanks going bad. My 99 was no different. (Also had a wacked out fuel level sensor, replaced in the same module with the pump)