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Discussion Starter #1
After doing the so called bb mod with a 4-40 screw my fuel pressure at idle is 72-74psi and will top 80 while driving when I let out of the go pedal. It stays above 55 with wot. Is this too much? performance so far seems to have decreased? Can't figure out why that would be?
 

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I installed a 6.0 fuel pump inline with the stock pump with the truck running I have 70 psi and at wot 100 psi and my truck has never run better
 

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Discussion Starter #6
Getting a lot of mixed messages? It smokes less then before and is either slightly slower or slightly faster but lacking the turbo lag, can't quite tell by seat of pants. Might take it back out or rind it down some
 

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Discussion Starter #7
Changed my mind after driving it on highway. I'm thinking that the fuel is atomizing better from the increased pressure therefore burning better inturn producing less smoke and more boost and LOWER egts! win all around.
 

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Im concerned about my fuel pressure also. Its running about 90 at idle. I've got a fuelab pump running to the bowl. I totally drilled out the stock regulator, and im using the stock 3/8" fuel line as the return. And its still keeping this much pressure. I need a regulated return BAD. Is this gonna damage my injectors in the long run?

Also, im seeing 90psi at the bowl, but would there be a pressure loss between there and the fuel rail, since im running stock lines from the bowl to the heads?
 

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Changed my mind after driving it on highway. I'm thinking that the fuel is atomizing better from the increased pressure therefore burning better inturn producing less smoke and more boost and LOWER egts! win all around.
Sorry, but 15-20psi more of fuel pressure will not make a noticable difference in drivability, unless you're going from 0 pressure to 15-20. Now jack that fuel pressure up to 2-300psi on a highly modded truck, and yeah, there very well could be a dyno measurable difference. ;)

If your injectors were able to generate a true 7:1 injection pressure to oil pressure ratio you would be seeing an additional 105-120psi at the nozzle over a theoretical 21,000psi. It wouldn't make a difference.

Dave
 

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Try to be @ 62psi +/-10 psi.
 

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Discussion Starter #11
I see your reasoning and would a agree with it however I haven't moded my truck in about two years and I know how she acts in bout every situation and she is definitly driving better, maybe its a fluke but it is true.
 

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I see your reasoning and would a agree with it however I haven't moded my truck in about two years and I know how she acts in bout every situation and she is definitly driving better, maybe its a fluke but it is true.
Well there's really only 2 options, lol:

Either your fuel pump is getting weak,

Or it's in your head, because in your previous posts you couldn't decide if it ran better or worse.

Stick it on the dyno, and see what it makes before and after. That will tell the tale. Butt dynos aren't nearly as accurate as a load dyno. :D

Dave
 

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If you run too high fuel pressures through too small fuel lines you will have cavitation problems. Sometimes nothing too serious but it wont help with performance.
 

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Discussion Starter #14
Ya it probably is because I still can't decide!! I don't think the pump is getting weak but maybe, I serviced the vehicle before I bought it from the previous owner and it only had 92k when I got it. Now has 127k. I know it was well cared for and never driven hard. Atleast before I drove it!!
;)
 
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