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Please help. Fuel pressure drops with rpm

 
Old 03-15-2019, 10:30 AM
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Default Please help. Fuel pressure drops with rpm

Hi All

First, I did do a search and couldn't find anything.

I am guessing that my setup isn't close to being substantial for my engine. Here it is:

I just installed a LQ4 whipple 2.9L in my 73 Camaro.

I have a Ricks tank that has a tiny opening. I tried squeezing dual pumps in through the opening and they just won't fit.

I have a new Walbro 450 in tank right now with -8 feed, -6 return.

I drove the car a tiny bit last year and it seemed to be going lean while trying to gently accelerate.

I started the car recently and while in the garage I revved the motor up a bit, maybe to 1800-2000 rpm and I watched the fuel pressure drop from 43 to about 38. So I know that I have an issue.

Any recommendations to what I should buy would be appreciated.

Thanks,

Roman
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Old 03-15-2019, 10:33 AM
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Is your fuel pressure regulator vacuum referenced?
Your fuel pressure will drop when you let off the throttle when revving.
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Old 03-15-2019, 10:38 AM
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Originally Posted by JoeNova View Post
Is your fuel pressure regulator vacuum referenced?
Your fuel pressure will drop when you let off the throttle when revving.
the regulator is vacuum referenced. I'm pretty sure it was dropping as I gave it throttle. I will check again.

Thanks.
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Old 03-15-2019, 11:33 AM
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Fuel pressure seems a little lower anyway. Why not increase it to 58 PSI?
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Old 03-15-2019, 11:44 AM
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That is true.

For some reason, I remembered the stock fuel pressure to be at 43?? I don't know why that number has stuck with me all of these years.

It shall be increased to 58. Thanks Joe, for pointing that out.

Thanks,

Roman
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Old 03-15-2019, 11:59 AM
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Most fuel injectors are rated at 43 PSI. A lot of fuel systems have operated on that pressure at some point. Most after 1999-2000 operate on 58 PSI, except direct injection.
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