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View Poll Results: What should be replaced or upgraded?
Upgrade to bigger injectors 0 0%
Upgrade to ZL1 fuel pump 0 0%
Both 2 100.00%
I have NO CLUE! LOL! 0 0%
Voters: 2. You may not vote on this poll

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Old 09-04-2018, 08:59 AM   #1
jaydubb71
 
Drives: 2009 Pontiac G8 GT
Join Date: Oct 2014
Location: United States
Posts: 6
Stock pump fuel pressure issue???

Good morning folks.

Yesterday, I was tuning a 2010 SS L99. Car has:

Tick Performance "stock stall" cam
Texas Speed full exhaust (headers to tailpipe)
Vararam

Start adding fuel and timing. Get above 5000 RPM and BUCK BUCK city. Im like "WTF?" Luckily I was monitoring injector duty cycle and fuel pressure.

I noticed the was going lean up top per my wideband. Add fuel and it gets worse. Noticed the injector duty cycle was almost 103% and the fuel pressure dropped as low as 48psi. Initially I was about to blame the injectors (My G8 has a bigger cam and never gets over 70% duty cycle. And we run the same injector...) until I noticed the fuel pressure...

I assume its the fuel pump. The owner is ordering a ZL1 pump today. Do yall think I made the right determination?

Thanks in advance. Take a look at the attached pics...
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Old 09-04-2018, 03:57 PM   #2
hunter1660

 
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Drives: 2011ss/rs camaro
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License the Fpcm in hp tuners and write data from zl1 Fpcm. It'll hold pressure thru high rpms and with boost pump your good. The stock ss Fpcm for whatever reason reduces pressure as rpm increases.
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Old 09-04-2018, 07:14 PM   #3
jaydubb71
 
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It's still requesting 58 psi tho. I will double check
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Old 09-04-2018, 07:26 PM   #4
hunter1660

 
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Yes..but it's not dropping to 50 + -
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Old 09-05-2018, 07:47 AM   #5
jaydubb71
 
Drives: 2009 Pontiac G8 GT
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Quote:
Originally Posted by hunter1660 View Post
Yes..but it's not dropping to 50 + -
Huh? According to HPT and the way the IDC went north for no reason, it appears that it is. And the how fuel table isnt commanding it.

This is from the engine side. I will pull the FP controller file this weekend and verify.
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Old 09-05-2018, 04:32 PM   #6
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I didn't change any of those values. Only the ones in the Fuel Control Module. It should be 2 tables to the right of the Fuel Pressure Table your showing in the fuel system. In the gen 4 section on hptuners search Fpcm and there's is 8or9 pages detailing the process.
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Old 09-06-2018, 03:45 PM   #7
jaydubb71
 
Drives: 2009 Pontiac G8 GT
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Quote:
Originally Posted by hunter1660 View Post
I didn't change any of those values. Only the ones in the Fuel Control Module. It should be 2 tables to the right of the Fuel Pressure Table your showing in the fuel system. In the gen 4 section on hptuners search Fpcm and there's is 8or9 pages detailing the process.
Thanks! I appreciate it!
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