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GM Bob
GM Bob, ASE Certified Technician
Category: Chevy
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Experience:  30 plus years. experience as GM technician, ASE Master Technician and GM Certified.
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I have a 2007 Chevrolet Suburban 2500 with the 6.0 engine.

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I have a 2007 Chevrolet Suburban 2500 with the 6.0 engine. It has begun in the last few weeks to intermittently overcrank after the engine has started. This morning it seemed to just crank along time before it would start and I had shut the key a try again before i got it to start. Any thoughts about where to start?

Hello! My name is***** to JustAnswer. I'm reviewing your question now, and will post back with your reply momentarily.

When its hard to start. The engine cranks long time. When it starts how does it run?

Do you have any engine lights on when its running?

Customer: replied 8 months ago.
It runs fine once it fires. No lights on once it starts. It started out over cranking after it started. That seemed to have stopped though.

Do you have a fuel pressure gauge?

Need to test the fuel pressure. Maybe week or not holding pressure.

Customer: replied 8 months ago.
I don't think so but I can get one or borrow one. Where do you attach the gauge to test the pressure?

There is a port on the passenger side on the fuel rail.

The fuel pressure should be 50-60 psi

Should not drop more than 5 psi in 3 min after pump shuts off.

Customer: replied 8 months ago.
Just turn the key on and let it pressurize?

Yes

It will only run for 2 sec. May have to key off wait 10 sec than key on again

Customer: replied 8 months ago.
How do I contact you again after I do that. It will be 2-3 days.

Save this web site and come back and post your results.

I will be contacted when you post.

Thank you

I'm just checking to see if you still need help?

Customer: replied 8 months ago.
I received the fuel pressure test kit but haven't tested it yet. I will either do it tonight or tomorrow. I did have one new symptom yesterday where nothing happened when I turned the key. I did it's 4 times then on the 5th try it finally turned. Will be in touch after testing the fuel pressure. Thanks

Thanks for getting back with me

Customer: replied 8 months ago.
The first cycle of the pump went to about 54 psi and lost about 6 psi in 3 minutes
The second cycle of the pump went 54 psi and lost about 4-5 psi in 3 minutes
Right after doing that the engine struggled to start (cranked for a long time) it seems to help if you pump the accelerator while it's cranking.
It also worth noting that when it cranks for a long time I hear a grinding noise intermittently that sounds the same as when you engage the starter on an engine that's already running.

If it starts and the engine RPM is not high enough. The computer keeps the starter engaged.

Did the fuel pressure keep dropping after 3 min?

When it was hard starting was the fuel gauge still connected?

Customer: replied 8 months ago.
I didn't let it go much past 3 minutes. I can do that if that would be helpful information. The fuel gauge was not connected when I started the engine. I can do that also if that will help diagnose. FYI-I replaced both fuel pumps and the fuel lines underneath the truck about 80K miles ago.

Yes that would helpful.

Trying to tell if the fuel is dropping. Ether draining back to the gas tank or leaky injector.

May want to try cleaning the throttle body plates also.

Customer: replied 7 months ago.
Sorry! Its been a busy few days! I did the fuel test again and with a cycle of the pump the pressure went right to 55 psi and didn't move for 15 minutes. If you cycle the pump or start the engine it goes to 60 psi and when you turn it off the pressure returns to 55 psi. The only difference between this pressure test and the last one was that the engine was warm this time and cold last time I did it.

Looks like there is no problem with the fuel system.

Will it only crank long after it sits over night?

Did you clean the throttle body?

Customer: replied 7 months ago.
More often when it's cold but it has done it when it's warm. The one time it didn't crank at all was warm (it probably sat for an hour that time). I did not clean the throttle body...I forgot about that assignment.

Can you keep the fuel gauge on the truck over night?

See if you have fuel pressure on startup.

Customer: replied 7 months ago.
Overnight the pressure dropped to 0. Came right back to 55 with one pump cycle. It did struggle to start with the "starter grinding noise". I was alone so I did not see what the fuel pressure was while it was struggling to start.

When you say grinding. Is this during the cranking like its slow?

If you hold the gas pedal down just a little does that help?

Customer: replied 7 months ago.
It's not cranking slow. The grinding is similar to the noise that you would hear if you tried to start an engine that's already running. I think pushing the accelerator does help when it's struggling to start.

Clean throttle body ?

Customer: replied 7 months ago.
Not yet. Is that what I need to do next?

Yes do that next.

Make sure the key is off when you do it.

Also need to drive it after cleaning.

There is a idle relearn procedure but you need a scan tool to perform it.

Just checking to see how's it going?

Customer: replied 7 months ago.
Finally got the throttle body cleaned tonight. After finishing that project we started the engine and it started fine and idled fine. Shut off the engine and aired up one of the tires and greased a door hinge. This took all of 5-7 minutes. Tried to start it again and got nothing but click. Tried several times and nothing. The information center said "service charging system" and the battery light was on. Put the battery charger on it in start mode and it fired right up. I should mention another symptom that has occurred several times and that is that after starting the truck, the headlights sometimes don't turn on. If you turn the light switch off and back on a couple of times the lights will then turn on. Is there any chance that a bad battery could cause all of these symptoms? I'm going to have the battery checked tomorrow.

Yes the low battery can affect starting. Because your throttle is electric.

As for the headlights not sure if the body control module would default them off. For a low battery.

Have never seen it before.

If the battery is more than 4 years old. I would replace it

Was the battery bad?

Do you still need more help?

If you can take a moment and rate may service.

Thank you

GM Bob and 4 other Chevy Specialists are ready to help you
Customer: replied 7 months ago.
Here's the update! The battery tested bad so I replaced it on Friday. Took the suburban on a 500 mile trip Saturday....no starting issues until Sunday afternoon. Another long crank with the starter grinding noise. Where do we go from here? Is it possible that it's a bad starter?

It is possible the starter is going bad.

When it makes the noise does it crank slow?

Its really hard to diagnosis with out hearing it.

Have not replaced vary many starters.

Customer: replied 7 months ago.
I don't feel like it's cranking slow at all, just cranks long. I can try to record it for you if that will help. It would be easier if it was more consistent.

Yes that would help.

When it makes the noise it is at the same time it crank long

Customer: replied 7 months ago.
Definitely only hear the noise when it cranks long. I will attempt to record it. Hopefully it will misbehave tonight when I leave the office.

Keep updated.

I will keep researching