My engine is hard starting

Tiny
SILVERADO2000
  • MEMBER
  • 2000 CHEVROLET SILVERADO
  • 4.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 32,000 MILES
Truck has 32,000 miles and is like new. This problem started 2-3 months ago. Battery is good, air filter clean. Truck starts immediately when cold (down to 20 degrees) and also when warm except if it has been off for 10-60 minutes then it will crank for a long time and then start at a low idle (200rpm for a bit) before catching on. Have tried the turn it on three times (3 seconds each time) trick with no success. If I hold the accelerator to the floor (as per owner's manual) the truck starts right up. Engine pulls hard over 4000 rpm with no missing or power loss. Does this problem sound familiar, and if so, what is the most likely source? Thank you
Saturday, March 10th, 2018 AT 8:18 AM

51 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good morning

From your description and the key is putting the fuel pedal to the floor, it sounds like it is flooded. by putting the pedal to the floor, it goes into clear flood mode.

This indicates an injector may not be sealing when the engine is turned off. that will allow fuel into the intake system.

if you can check the fuel pressure with a gauge, there is a port on the fuel rail, you can monitor the pressure. let the truck get hot and then turn it off. watch the pressure and see if it drops off.

These guides can help us fix it.

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

and

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Roy
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Saturday, March 10th, 2018 AT 9:27 AM
Tiny
JIMVANCLEAVE
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 230,000 MILES
2000 Chevy Silverado 5.3 Vortec Starts very hard when it's cold(it loads up, once it starts and gets the excess fuel out it runs fine)
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Has the check engine light come on? It sounds like a temp sensor, but I can't be sure without the code.

Let me know.
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
JIMVANCLEAVE
  • MEMBER
  • 2 POSTS
Air temp sensor?
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
The engine temp sensor. It tells the computer what the ambient temp is as well as the coolant temp sensor. With that information, the computer determines how rich to make the fuel mixture to start the engine and keep it running. If the temp sensor tells the computer it is -40°F outside, it will dump fuel to start and maintain the engine.

Let me know if you have other questions.
Joe
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
WINCHELL
  • MEMBER
  • 5 POSTS
  • 2000 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 92,000 MILES
It has a 5.3 liter. If engine ran for a while and shut off for 20 min or more it doesnt want to start untill I press the gas pedal. If left over night it fires right up. I ran full diagnosis and no codes and nothing wrong. I have replaced the IAC valve, plugs and wires, didnt help. Truck runs good and drives fine good idle @ 600 RPMs. I am at a loss as what to do please help
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
DENNYP
  • MECHANIC
  • 1,824 POSTS
Check for fuel leaking into the vacuum hose to the fuel pressure regulator.
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
WINCHELL
  • MEMBER
  • 5 POSTS
I checked the vacume line from the regulator and there was gas in the line. I replaced it and seems to be working good now. Thanks a million!
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
GORDON TARRANT
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET SILVERADO
Engine Mechanical problem
2000 Chevy Silverado 6 cyl Two Wheel Drive Automatic 241000 kilometers

first start of the day is a hard start warm or cold shop crank and crank and finally fires up.
After first start it runs fine no missing at all.
I shoot some carb cleaner in the throttle body and it fires up right away. No check engine lights come on or anything.
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
It sounds like low fuel pressure. What I need you to do is check fuel pump pressure. Here is a how to:

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

Pay special attention to fuel pressure drop off. THat is when you shut the key. Does the system hold pressure or does it drop quickly?

Let me know.

Joe
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
GORDON TARRANT
  • MEMBER
  • 2 POSTS
Thanks for the advice that, s exactly what it was
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Monday, January 25th, 2021 AT 12:16 PM (Merged)
Tiny
KHEWLETT511
  • MEMBER
  • 5 POSTS
  • 2000 CHEVROLET SILVERADO
  • 4.3L
  • V6
  • 4WD
  • MANUAL
  • 102,000 MILES
This truck has been hard to start since I got it over a year ago. Now I am trying to fix it. 75% of the time it takes a few couple second cranks before it turns over and when it does it takes a second to get up to idle rpm's where it will run okay. I do not notice any other problems besides the starting. I have cleaned MAF and throttle body and it may have helped a little but still does it. It has thrown a code for running rich in both banks and random misfire a while back. I am not sure where to start but would like to know your opinions.
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi and thanks for using 2CarPros.com.

Since you are getting a rich code, the first thing I would check is the coolant temperature sensor. This sensor tells the computer how rich or lean to make the fuel mixture. What you need to do is this. Get a live scanner. With the engine cold, scan through until you come to the coolant temperature sensor (CTS). The CTS should be telling the computer the coolant is about the same temperature and ambient temperatures. If it tells the computer it is -40 degrees F (that is an extreme) the computer will react by providing a rich fuel mixture for the vehicle. Thus, it will be hard to start, run poorly. I attached a picture of the sensor location if you find that is the problem.

Next, if that is fine, you need to check fuel pump pressure. If there is a faulty fuel pressure regulator, it will cause the same issues. Here are directions for checking pressure and the regulator:

Fuel pressure should be: Key On Engine Off 60 - 66 psi

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Okay, one last thing. If the fuel pressure is good, then I question if there is a leaky fuel injector.

If the check engine light is on and this information does not help, let me know all the codes which are found.

Take care,
Joe
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
KHEWLETT511
  • MEMBER
  • 5 POSTS
Thank you I will try this and get back to you.
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Sounds like a plan. Let me know what you find.

Take care,
Joe
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
CHRISREIS
  • MEMBER
  • 3 POSTS
  • 1999 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 188,000 MILES
My truck will not start when warm. I replaced the fuel pump, fuel pump relay, plugs and plug wires. The dealer replaced the fuel pressure regulator, fuel filter, and cleaned the throttle body. The truck starts normally when cold and runs fine at all times. However, when the engine is not cold, it won't start on the first crank. It always starts on the second crank. I know the injectors will run much leaner when the engine is warm, its seems as though they're running too lean. Any suggestions you could offer would be appreciated.
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
HAs it ever given any codes? (Check engine light) What brand fuel pump was used? I have installed customers aftermarket pumps just to take them right back out for low pressure/flow
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
CHRISREIS
  • MEMBER
  • 3 POSTS
No, check engine light has not come on at all. Fuel pump was bought from Chevrolet dealer. It looked identical to the one that came out of it. If I wait less than 5 minutes to restart it when warm, it usually starts the first time.
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,750 POSTS
I would look at the fuel pressure regulator again. Its simple to check. Just remove the vacuum line and see if gas is present. If it is or the hose is soft. Replace the regulator again.
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Monday, January 25th, 2021 AT 12:17 PM (Merged)
Tiny
CHRISREIS
  • MEMBER
  • 3 POSTS
Pressure regulator is fine - hose is firm and dry, no gasoline is present. Today I let it crank for about 10-12 seconds, still didn't start. Still started second time no problem but there was a distinct odor I noticed from inside. Not sure what it was but I think it may be related.
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Monday, January 25th, 2021 AT 12:17 PM (Merged)

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