fuel pressure question
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Teching In
Joined: Sep 2012
Posts: 5
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From: North Carolina
fuel pressure question Hello, i have a 98 trans am m6 with ms3 cam 112 lsa, 243 heads, ls7 coils, ls6 intake, BBK LT's, stock internals and fuel pump with 32lb/hr injectors. I was just wondering if this is normal, I turn the key to accessory, the fuel pressure goes up to 60psi, then drops to 50psi about 1-2 seconds later. Then the pressure slowly leaks down, I've seen it go as low as 40psi before i started the car. Once the car is started, the needle rapidly fluctuates between probably 55-60psi. Is this normal? because the car runs like complete crap. It ran like this before but i just swapped out the injectors and got it re-tuned and it seemed to have gone away. Thanks for your help.
I am having a similar issue. pressure will eventually do to zero after half an hour after key is off.
OP, I pulled my rail and put red solo cups under each injector, primed the system and waited for it to drop to zero, the cups were dry so it's not the injectors. I am suspecting the filter/regulator may nut be holding pressure correctly. Hope this helps.
OP, I pulled my rail and put red solo cups under each injector, primed the system and waited for it to drop to zero, the cups were dry so it's not the injectors. I am suspecting the filter/regulator may nut be holding pressure correctly. Hope this helps.
Teching In
Joined: May 2014
Posts: 39
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Is your regulator vacuum referenced??
If so, the fluctuations you are seeing on the gauge might indicate a vacuum leak, which could also explain why your car is running like crap.
As far as the pressure dropping, I am not expert on your car, but I think most cars have a check valve either in the fuel return line, or in the fuel pump itself, so that the system holds pressure over a specific amount of time. If it has failed, then as soon as the pump stops, the pressure will begin to drop.
If so, the fluctuations you are seeing on the gauge might indicate a vacuum leak, which could also explain why your car is running like crap.
As far as the pressure dropping, I am not expert on your car, but I think most cars have a check valve either in the fuel return line, or in the fuel pump itself, so that the system holds pressure over a specific amount of time. If it has failed, then as soon as the pump stops, the pressure will begin to drop.
