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Fuel pressure question

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Old 09-16-13, 03:46 PM
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Fuel pressure question

When you turn the ignition (not cranking), what pressure should I set the regulator?

Thanks
Old 09-16-13, 03:54 PM
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Standard pressure is 43.5 psi (3 bar) and should be set with the engine idling and the regulator's vacuum nipple open to the the atmosphere.
Old 09-16-13, 04:04 PM
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well, i can do that when i get it idling -- I have a hard time starting that's why i asked.

i need to know when you are in the ignition (what pressure supposed to be showing)? 35 ?
Old 09-16-13, 05:21 PM
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You can prime the fuel pump and set the base pressure with vacuum hose off the FPR.
Old 09-16-13, 07:04 PM
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ok---thanks i got it started by squirting lots of starting fluid.
once started and a little bit hot, it will start again.

if anyone knows how i can change the map to start faster when its cold -- pls help me.
Its powerfc - single turbo
Old 09-16-13, 09:27 PM
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Originally Posted by 0110-M-P
Standard pressure is 43.5 psi (3 bar) and should be set with the engine idling and the regulator's vacuum nipple open to the the atmosphere.
WRONG, nothing worse than the wrong answer or people who do not use the manaul!

36 to 38 psi.
Old 09-16-13, 10:26 PM
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Originally Posted by cewrx7r1
WRONG, nothing worse than the wrong answer or people who do not use the manaul!

36 to 38 psi.


You have a point but at the same time he can vary injector output with the aftermarket ecu. So he doesn't have to run at stock pressure levels. Atomization would be better would it not?
Old 09-17-13, 12:02 AM
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Originally Posted by t-von
You have a point but at the same time he can vary injector output with the aftermarket ecu. So he doesn't have to run at stock pressure levels. Atomization would be better would it not?
interesting question...

whats the answer??

could help with 850 primaries...

if there is better atomization I might get some leaner idle.
Old 09-17-13, 07:44 AM
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Originally Posted by cewrx7r1
WRONG, nothing worse than the wrong answer or people who do not use the manaul!

36 to 38 psi.
I guess I should have been more clear. I assumed (maybe prematurely) that because he was trying to adjust the base pressure, he is running an aftermarket setup. Turns out I was correct since he later stated that he is running a PFC and single turbo.

The industry standard in which most injector flows are measured is 43.5 psi and is what the vast majority of people in the world use as their base pressure when setting up a new aftermarket fuel system.

The RX-7's factory fuel system on the other hand uses a base pressure of 36-38 psi as you stated.

No need for the all caps WRONG when I was far from it.
Old 09-17-13, 10:35 AM
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Atomization could potentially be better, but it's not something that can be assumed. Anyone care to provide any papers showing the effects of increased differential pressure on the old, stock injectors? Legitimately curious.

Additionally, if one keeps injector duty cycle constant, raising differential (base) pressure will also increase flowrate. So you'd likely need to retune the entire map with changes in base pressure. It's not as easy as simply raising base pressure and getting leaner afr. If your standalone has a minimum injector on-time like the PFC, then you'll quickly reach a point of diminishing returns.

Lastly, fd secondaries suck as primaries for a LEAN idle with PUMP gas. The stock primaries work unbelievably well with stock/street ports. Unless you're going with e85, the proper solution for a rich idle with 850cc primaries is to just ditch the pieces of ****.
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