C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

fuel pump problems

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Old Sep 24, 2013 | 06:02 PM
  #21  
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Your new fuel pump can and will go over 75-80 pounds. Just adjust the regulator to what ever you want. The stock style regulator is what's causing the 38 pounds not your fuel pump. All the new replacement FPR's I've bought lately cut off at 38 pounds which is only good for some earlier models yet they advertise that they fit all years.

As a side note my FSM says when doing the hose pinch test to try to keep the back pressure under 60 pounds so you don't create leaks at your fuel rail. Keeping that in mind when I installed my new adjustable FPR I backed it out two full turns before hitting the key. That way I didn't blow any seals before getting the air out of the system and checking the real pressure. It fired up at 37 pounds and a couple of turns later I had it at 46 pounds which is just right for my 96'.

Last edited by Klyde; Sep 24, 2013 at 06:49 PM.
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Old Sep 25, 2013 | 06:32 AM
  #22  
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Originally Posted by Klyde
Your new fuel pump can and will go over 75-80 pounds. Just adjust the regulator to what ever you want. The stock style regulator is what's causing the 38 pounds not your fuel pump. All the new replacement FPR's I've bought lately cut off at 38 pounds which is only good for some earlier models yet they advertise that they fit all years.

As a side note my FSM says when doing the hose pinch test to try to keep the back pressure under 60 pounds so you don't create leaks at your fuel rail. Keeping that in mind when I installed my new adjustable FPR I backed it out two full turns before hitting the key. That way I didn't blow any seals before getting the air out of the system and checking the real pressure. It fired up at 37 pounds and a couple of turns later I had it at 46 pounds which is just right for my 96'.
Thank you...that other post had me confused...thought I had this right...i'm a little new to fuel injection, not engines...jon at fic had told me to install his new diaphragm and spring and adjust the pressure using the new adjustable reg.... that last post made me feel like somebody sent me to get a left hand wrench....
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Old Sep 25, 2013 | 08:02 AM
  #23  
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Originally Posted by playsdixie
...that other post had me confused...thought I had this right.... that last post made me feel like somebody sent me to get a left hand wrench....
Because you previously stated
" " the fuel return line...pinched it off...pressure went quickly to 38"

With the return line pinched you have taken the ( possibly faulty ) fuel regulator out of the equation so your pump
or fuel system is only generating 38 psi line pressure at max.
If your pump was good you would have seen the pressures noted above

My previous comment stands ; you can't get any more pressure than what your pump generates at present.
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Old Sep 25, 2013 | 04:22 PM
  #24  
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Originally Posted by vetteoz
Because you previously stated
" " the fuel return line...pinched it off...pressure went quickly to 38"

With the return line pinched you have taken the ( possibly faulty ) fuel regulator out of the equation so your pump
or fuel system is only generating 38 psi line pressure at max.
If your pump was good you would have seen the pressures noted above

My previous comment stands ; you can't get any more pressure than what your pump generates at present.
after 38 # the line to the pulsator started leaking back into the tank...thats why the pressure dropped so quickly...although I haven't actually tested for top psi with the pump now, i'm sure it's working fine now..i'm rebuilding the top of the engine, with a new regulator so i'll find out soon enough as jon tells me I need 43.5 with these new injectors...
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Old Sep 25, 2013 | 07:24 PM
  #25  
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Originally Posted by playsdixie
very interesting...how then, do I get higher pressure?? This is a new fuel pump....
I have the exact same problem, I was under the impression an adjustable fpr would help.
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Old Sep 25, 2013 | 08:56 PM
  #26  
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Originally Posted by Pete919
I have the exact same problem, I was under the impression an adjustable fpr would help.
it's been a long thread....you'll have to say what the exact same problem is....i'm assuming mine is corrected...I guess I could pinch a fuel line to see if pressure is higher than 38 ...since i'm installing a new reg i'll wait...I will admit that pinching the lines is the easiest way by far
to troubleshoot the fuel system pressure problems....came a little further down the troubleshooting guide than I would have liked....since I have the manual, I always have been trying to start at the beginning.

Last edited by playsdixie; Sep 25, 2013 at 09:16 PM.
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