Weird hard start

[Shuttlemandan]

Hey guys. New here and need some help. I have a 2011 Yukon SLE 5.3. I leave my house in the morning. Starts and runs fine. Drive about 25 miles to work. Work all day. When I go to leave work it will crank and not fire till I step on the gas pedal. Once it’s running it runs and drives perfect. I can shut it off and it will start again fine. No lights or codes. This has happened 2 days in row. Any ideas? Thanks

 

[wjburken]

Hey guys. New here and need some help. I have a 2011 Yukon SLE 5.3. I leave my house in the morning. Starts and runs fine. Drive about 25 miles to work. Work all day. When I go to leave work it will crank and not fire till I step on the gas pedal. Once it’s running it runs and drives perfect. I can shut it off and it will start again fine. No lights or codes. This has happened 2 days in row. Any ideas? Thanks

Welcome to the forum from Iowa.

You might be having a fuel pressure issue starting.

 

[Shuttlemandan]

Thanks. Now it’s seems to hard start on every cold start. Runs rough for 10-15 seconds then it’s fine. Fuel pump was replaced 2 months ago. I added an AFM disabler about 2 weeks ago. Gonna try to unplug that and see what happens. I did notice some rough running on cold start once I installed that.

 

[wjburken]

Thanks. Now it’s seems to hard start on every cold start. Runs rough for 10-15 seconds then it’s fine. Fuel pump was replaced 2 months ago. I added an AFM disabler about 2 weeks ago. Gonna try to unplug that and see what happens. I did notice some rough running on cold start once I installed that.

Why was the vehicle doing that caused you to replace the fuel pump?

Did you do the work yourself or hire it done?
What brand of pump did you go with?

Can’t remember if it would cause this symptom, but there is a hose/line that if not put back and routed properly, can get pinched between the tank and the frame of the vehicle. I think @Doubeleive posted about this but I could be thinking of the wrong person.

 

[Shuttlemandan]

Fuel pump was leaking. Dealer I bought it from replaced it

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics, please.

I cannot personally assist you with this issue, but lots of folks here in the Forum have posted and discussed issues associated with the fuel delivery system. Some folks have already provided some feedback and suggestions to you, and others will chime in.

 

[Doubeleive]

Why was the vehicle doing that caused you to replace the fuel pump?

Did you do the work yourself or hire it done?
What brand of pump did you go with?

Can’t remember if it would cause this symptom, but there is a hose/line that if not put back and routed properly, can get pinched between the tank and the frame of the vehicle. I think @Doubeleive posted about this but I could be thinking of the wrong person.

wasn't me but I would def throw a fuel pressure tester on it and see what it is showing, key turned to run (not start) it should show over 50psi normally around 60-65psi, then once started it should show running psi of around 45psi a tester can be picked up from harbor freight for about $30.
in the meantime you could try turning the key to run leave it for a few seconds, turn it back back to off and then back to run again for a few seconds a couple times, then start it and see if there is any difference, doing this will allow it to build up a little pressure if the pump is going funky or there is a pinched line like Wade mentioned.

 

[Shuttlemandan]

Thanks guys. Thinking of doing and alcohol and fuel trim reset too

 

[kbuskill]

Could be a line pinched from incorrect routing or it could be a bad purge valve for the EVAP system dumping fuel vapors into the intake which basically floods the engine.

When you say "step on the gas" I assume you mean hold it to the floor while cranking the engine which puts the ECM in "clear flood" mode which turns off the fuel injectors allowing the engine to burn off the fuel vapors.

 

[Shuttlemandan]

Could be a line pinched from incorrect routing or it could be a bad purge valve for the EVAP system dumping fuel vapors into the intake which basically floods the engine.

When you say "step on the gas" I assume you mean hold it to the floor while cranking the engine which puts the ECM in "clear flood" mode which turns off the fuel injectors allowing the engine to burn off the fuel vapors.

correct