2005 Silverado 4.8L engine. Hard starting when engine is hot. If restarting immediately fires first crank, same as cold. If Truck stands for 10...

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Hello Hugh

How are you doing. Looks like that you replaced pretty much everything  but still failing. Here's the thing that usually  causes this issue and I noticed that it's not on your list. I am suspecting a failing CKP sensor, the functional objective for the crankshaft position sensor is to determine the position and/or rotational speed (RPM) of the crank. Engine Control Units use the information transmitted by the sensor to control parameters such as ignition timing and fuel injection timing. If it's faulty the engine may intermittently start/not start be it hot or cold. 

Below is what it looks like and the location Hugh

There will come a point that the truck will not start at all if the CKP sensor reached it's end of life. Since it's not replaced yet I believe now is the time to replace it so that it can get back to it's normal operating state. Please let me know if there's anything else I can add or help you with. I'll be standing by for your response.

Thank you

Relly

Will it start immediately when the engine is cold Hugh?

By the way, when was the last time you replaced the fuel pressure regulator Hugh? It can be failing that's why it will not hold the right fuel pressure after turning it off.

You may want to consider replacing the fuel pressure regulator too Hugh

Relly

Well, a faulty fuel pressure regulator will show no codes Hugh. By the way I am thinking of something. Let's say you start the truck and turn it off when it's warm, it will not start right back up right? Will take 6 to 8 cranks before it starts. When it's warm, turn the engine off and remove the spark plugs. Check if the spark plugs are wet. There can be fuel flooding that's why it will not fire up when you start it because it's soaking in fuel. Will start after a few cranks because the stuck fuel will be burn.

Well, a faulty fuel pressure regulator will show no codes Hugh. By the way I am thinking of something. Let's say you start the truck and turn it off when it's warm, it will not start right back up right? Will take 6 to 8 cranks before it starts. When it's warm, turn the engine off and remove the spark plugs. Check if the spark plugs are wet. There can be fuel flooding that's why it will not fire up when you start it because it's soaking in fuel. Will start after a few cranks because the stuck fuel will be burn.

Have you tried cleaning the MAF sensor and the filament inside the air filter tube? Try to remove it and clean the filament with a carb cleaner. It may not be giving the correct air and fuel mixture during start up after turnging the engine off.

Yes it will have something with the throttle body Hugh. I strongly suggest that you clean the strainers for it can be clogged with dirt and carbon

Hello Hugh

How are you doing? This is a follow up regarding my assistance. Is there anything else I can add or help you with? Let me know if it's been helpful and please keep me posted on the progress. I'll be waiting for your response.

Thank you

Relly de Jesus

Hello Hugh

How are you doing? This is a follow up regarding my assistance. Is there anything else I can add or help you with? Let me know if it's been helpful and please keep me posted on the progress. I'll be waiting for your response.

Thank you

Relly de Jesus

Hello Hugh

How are you doing? This is a follow up regarding my assistance. Is there anything else I can add or help you with? Let me know if it's been helpful and please keep me posted on the progress. I'll be waiting for your response.

Thank you

Relly de Jesus

Hello Hugh

How are you doing? This is a follow up regarding my assistance. Is there anything else I can add or help you with? Let me know if it's been helpful and please keep me posted on the progress. I'll be waiting for your response.

Thank you

Relly de Jesus

Hello Hugh

How are you doing? This is a follow up regarding my assistance. Is there anything else I can add or help you with? Let me know if it's been helpful and please keep me posted on the progress. I'll be waiting for your response.

Thank you

Relly de Jesus