255lph pump installed runs like crap

95gt444

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Planning on a vortech in the future so I upgraded fuel pump to bbk 255lph kit. Changed the filler neck grommet. Started up after priming pump idles great but has no power at low rpm or less then full throttle engine also sounds diffrent then it did before. With stock injectors do I need an adjustable regulator to lean it out?

mods as follows


Bbk 75mm tb
bbk cai
bbk 75mm maf
trickflow street heat intake
trickflow 75mm elbow
emimissions gone
a/c and p/s elimmated
mac shorty headers mac offload h
flowmaster catback
 

BLWNBYU

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Pull the vacuum line off your regulator and see if there is any fuel in it
 

330CubeGt

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If you think about it all your mods listed are doing is leaning it out and the computer is taking care of fuel compensation.


And going from a say 90lph to a 255 won't make the car run rich as long as nothing else has changed.

-330CubeGt
 

BLWNBYU

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If you think about it all your mods listed are doing is leaning it out and the computer is taking care of fuel compensation.


And going from a say 90lph to a 255 won't make the car run rich as long as nothing else has changed.

-330CubeGt

Well, one would think that, but I just changed fuel systems and it dropped my AFR 3 points at idle, with NO other changes and I've spent a week trying to figure it out... I have numerous people stumped over on corral lol
 

OnyxCobra

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Yeah I have to say just switching my fuel pump I didn't notice any difference in how my car ran. We have a fuel return so anything the engine doesn't use goes back to the tank.
 

95gt444

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If the pump is pushing more volume possible regulator can't keep up?
 

330CubeGt

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Yeah I have to say just switching my fuel pump I didn't notice any difference in how my car ran. We have a fuel return so anything the engine doesn't use goes back to the tank.

7 Mustangs later thats all I have ever experienced. Even with dual 255s or a single 340

If the pump is pushing more volume possible regulator can't keep up?

Your pushing more volume to the same regulator and injectors, all its going to do for now is make sure you dont run out of fuel up top in the higher rpm's. But thats nothing you have to worry about right now.All the extra fuel its able to put out will make its way back to the tank through the return.
Guys run more pump then you are on stock regs and dont have issues.Not saying its the beat but it's been done.

-330CubeGt
 

95gt444

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Car ran perfect with stock pump so not sure what the deal is. Tank is very low on fuel, maybe just not enough gas, lol. Pump and strainer are sitting in the baffle. Clamps and wires tight made sure hose didn't get cut when putting it in. All lines and electrical connectors clipped in place
 

330CubeGt

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So your trying to diagnose a problem and your very low on gas.

So im thinking you might be the problem?

-330CubeGt
 

95gt444

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I didn't want too add more gas if I have to pull the pump back out make it heavier. I'll add some fuel. The engine runs great, but under load it hesitates,unless I give it lots of throttle, but accelerating slowly it hesitates.
 

BLWNBYU

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Car ran perfect with stock pump so not sure what the deal is. Tank is very low on fuel, maybe just not enough gas, lol. Pump and strainer are sitting in the baffle. Clamps and wires tight made sure hose didn't get cut when putting it in. All lines and electrical connectors clipped in place

Once you have emptied the tank it takes quite a bit of fuel to be able to make it back into the sump.....
 

95gt444

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Yeah I didn't realize how low it was I put a gallon of 87 I had for my mower, it's raining so no test drive but seems to run and sound way better then before. Is a adjustable fpr and fuel psi guage worth it?
 

95gt444

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Drove car today much better, still feels sluggish a little. Psi at rail is 36psi vac line hooked up and 45 with vac line off regulator. Can i advance timing more now with more fuel psi currently at 10degrees but sct4 chip so not sure if the chip advances it?
 

toyman

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Drove car today much better, still feels sluggish a little. Psi at rail is 36psi vac line hooked up and 45 with vac line off regulator. Can i advance timing more now with more fuel psi currently at 10degrees but sct4 chip so not sure if the chip advances it?

No. By increasing the fuel pressure you gain nothing at idle and cruise except make the ECU adjust the injector pulse width to bring the AFR back into spec. This occurs because the ECU is programed based on a fuel load delivered at about 39 psi. At WOT the AFR sensors are turned off and the ECU uses a look-up table to deliver fuel when the TPS sensor is above about 75% open. What you can do is increase the base timing until the engine starts to ping. You might be able to see 14* advance with 87 octane but with the chip you don't want to physically make this change as it has probably been done in the SCT tune. The chip may have altered the oem timing settings but fuel load and timing are not related in the way you are thinking.
 

95gt444

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Can too much fuel psi cost me power though with vac line off should be 39psi I'm am currently at 46psi
 

RichV

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It can. My tuning guy would not recommend over 42. Can you turn it down?
 

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