Excessive Cranking

Jason Mcdonaldson · February 4, 2024

Hey guys. Thank you for taking your Time to read my post. I apologize for posting this in the wrong forum, I couldn’t find the correct one.

i have a 2009 Chevy suburban 1500 with the 5.3L V8, and I’m having 2 problems with her. I’ll start with the first problem to bot bore you guys haha. The truck is cranking excessively and dies every time I cold start her. It cranks like crazy, barely starts, then dies again. Rinse and repeat 2 times and it’ll start. I run E-85 in her and the truck has 167,000 miles. I replaced the purge valve solenoid to no avail. Poured seafoam and didn’t fix it either. I tested the fuel pressure and here’s what I got. It hovers from 50- 58 PSI running, and when I turn it off and let it sit for a little it drops to about 42/43 psi. Does it have a vacuum leak or should I get a new fuel pump. When driving, the truck acts completely normal again.

thank you guys so much!

asilverblazer · February 5, 2024

Sounds like check valve in the fuel pump is no good. Replace the fuel pump.

Before doing so I would put a gauge on the test port to more closely monitor the fuel pressure. Install the gauge, let the engine run to confirm the pump does build proper pressure. Shut the engine off and confirm that fuel pressure bleeds off. If pressure bleed off is significant (overnight) cycle the key from off to run this runs the pump prior to starting. Make sure this priming action brings fuel pressure back up to where it should be, then try starting.

Edit: If it is the pump use only an OEM pump, unless you like changing them.

Edited February 5, 2024 by asilverblazer

Jason Mcdonaldson · February 6, 2024

Ok awesome thank you asilverblazer. I’m going to do this tomorrow and get right back to you guys. Would you like me to rent another tester and leave it overnight to see if the pressure bleeds off?

thank you

asilverblazer · February 6, 2024

10 hours ago, Jason Mcdonaldson said:

Would you like me to rent another tester and leave it overnight to see if the pressure bleeds off?

I assumed you owned a tester. I would rent/borrow/buy one to confirm:

1. How much pressure has bled off? It would have to bleed off basically all of it to cause the symptoms you exhibit. If all the fuel pressure bleeds off, that is a bad check valve and the pump must be replaced anyways.

2. Is "barely starts, then dies" due to low fuel pressure? If the fuel pump builds proper pressure and maintains it, then "barely starts, then dies" isn't caused by the lack of fuel pressure and must be diagnosed separately. (Not likely)

3. Does priming the fuel pump...

On 2/5/2024 at 10:30 AM, asilverblazer said:

cycle the key from off to run this runs the pump prior to starting. Make sure this priming action brings fuel pressure back up to where it should be, then try starting.

...allow the engine to start and run normally? If priming the fuel pump to achieve proper pressure resolves item number 2, or lessens it to a noticeable degree, you've confirmed that the fuel pump has to run long enough to rebuild enough fuel pressure at start up to start and run normally.

On 2/4/2024 at 2:19 PM, Jason Mcdonaldson said:

I tested the fuel pressure and here’s what I got. It hovers from 50- 58 PSI running, and when I turn it off and let it sit for a little it drops to about 42/43 psi.

Depends how long this "sit for a little" is - if that amount of drop is overnight, I don't think that is enough to create the degree of difficulty starting you exhibit.

Shorter response... I think its probably the fuel pump 85% certainty,

newdude · February 6, 2024

On 2/4/2024 at 3:19 PM, Jason Mcdonaldson said:

Hey guys. Thank you for taking your Time to read my post. I apologize for posting this in the wrong forum, I couldn’t find the correct one.

i have a 2009 Chevy suburban 1500 with the 5.3L V8, and I’m having 2 problems with her. I’ll start with the first problem to bot bore you guys haha. The truck is cranking excessively and dies every time I cold start her. It cranks like crazy, barely starts, then dies again. Rinse and repeat 2 times and it’ll start. I run E-85 in her and the truck has 167,000 miles. I replaced the purge valve solenoid to no avail. Poured seafoam and didn’t fix it either. I tested the fuel pressure and here’s what I got. It hovers from 50- 58 PSI running, and when I turn it off and let it sit for a little it drops to about 42/43 psi. Does it have a vacuum leak or should I get a new fuel pump. When driving, the truck acts completely normal again.

thank you guys so much!

Could be a weak pump.

Do you run E85 exclusively or do you run regular gas in it every once and a while? The older trucks are designed to run E85 but not non stop. Needs some regular fuel in them to lubricate the fuel system. GM used to have some info published on this but of course I can't find it.

Edited February 6, 2024 by newdude

Jason Mcdonaldson · February 7, 2024

On 2/6/2024 at 8:50 AM, asilverblazer said:

I assumed you owned a tester. I would rent/borrow/buy one to confirm:

1. How much pressure has bled off? It would have to bleed off basically all of it to cause the symptoms you exhibit. If all the fuel pressure bleeds off, that is a bad check valve and the pump must be replaced anyways.

2. Is "barely starts, then dies" due to low fuel pressure? If the fuel pump builds proper pressure and maintains it, then "barely starts, then dies" isn't caused by the lack of fuel pressure and must be diagnosed separately. (Not likely)

3. Does priming the fuel pump...

...allow the engine to start and run normally? If priming the fuel pump to achieve proper pressure resolves item number 2, or lessens it to a noticeable degree, you've confirmed that the fuel pump has to run long enough to rebuild enough fuel pressure at start up to start and run normally.

Depends how long this "sit for a little" is - if that amount of drop is overnight, I don't think that is enough to create the degree of difficulty starting you exhibit.

Shorter response... I think its probably the fuel pump 85% certainty,

Alright awesome the new fuel pump is coming today. Today when I was trying to start my truck to check the fuel pressure, the pump seemed to not be having it. It was misfiring and shut off over 8 times that I kept restarting it. It was low on gas but still has 50 miles left in it. I poured in a couple gallons of 91 from the tank from my ATV’s and she fired right up. I think it would have fired up regardless since it started and died so many times to prime the pump. When I turn the key into the ON position and back off multiple times, it still cannot start without constantly dying. I’m going to install the new fuel pump today and get right back to you guys. Sorry I didn’t respond yesterday, the pump had not been ordered yet

thank you guys so much!

Jason Mcdonaldson · February 7, 2024

21 hours ago, newdude said:

Could be a weak pump.

Do you run E85 exclusively or do you run regular gas in it every once in a while? The older trucks are designed to run E85 but not non stop. Needs some regular fuel in them to lubricate the fuel system. GM used to have some info published on this but of course I can't find it.

That’s exactly what I was thinking. I ordeeed a new ACDELCO pump to swap today. I hope I don’t have a vacuum leak xD. But I highly doubt it

asilverblazer · February 7, 2024

59 minutes ago, Jason Mcdonaldson said:

When I turn the key into the ON position and back off multiple times, it still cannot start without constantly dying.

This is why I'd like to see fuel pressure readings, the pump should eventually prime so that it can start without the continued dying.

Jason Mcdonaldson · February 7, 2024

1 hour ago, asilverblazer said:

This is why I'd like to see fuel pressure readings, the pump should eventually prime so that it can start without the continued dying.

I’m getting the readings right now, I’ll get back to you guys right away. Would you like readings from it in the “on” position and run position. How long would you guys like for me to let it sit to see if the pressure bleeds off

Mack

asilverblazer · February 7, 2024

Let it sit as long as you normally do (overnight?) so that it gets to the point were it is hard to start and dies.

Once it has bled down as far as it will go, cycle the key as many times as needed to get pressure back up to 50+PSI. (Or as high as you can get it.) Then try starting the engine while watching what the fuel pressure does.