2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

odd problem, running rich, but low fuel pressure and low pump voltage...wtf

Old May 22, 2006 | 12:51 AM
  #1  
DREYKO's Avatar
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I "lost" my emissions....
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From: lillington, nc
odd problem, running rich, but low fuel pressure and low pump voltage...wtf

ok i run rich, you can smell it, but my fp is pushing 60psi max and holding at 50psi. and my pump gets 11 volt, with most of the crap in my car turned off. wtf? why is it rich? and could this be my low power problem. im 90% sure of it, but i dont know.
any thoughts?
88 gxl w/ 91 engine. 0 emissions. header removed 5/6 ports ect. the list goes on...
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Old May 22, 2006 | 01:05 AM
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From: Rohnert Park CA
Double check at the fuel pump relay, what the voltage output is.

If you have that big of a loss from the relay, then you need to run new wires, but if the output at the relay is only 11 volts then you need a new relay.

That is if your car has normal 14.4 volts everywhere else
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Old May 22, 2006 | 01:14 AM
  #3  
DREYKO's Avatar
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I "lost" my emissions....
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From: lillington, nc
what about the lack of power and running rich with low pressure ect
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Old May 22, 2006 | 10:34 AM
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From: Rohnert Park CA
What are you using for a ECU? What is the condition of the injectors?
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Old May 22, 2006 | 10:59 AM
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DREYKO's Avatar
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I "lost" my emissions....
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From: lillington, nc
stock 88 ecu, injectrs need cleaning. but if it has low pressure how can it run rich?
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Old May 22, 2006 | 11:04 AM
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From: Rohnert Park CA
If you have injectors leaking, you would be running rich.

Also your timing may also be off, remember the S5 used sparkplugs in slightly different locations. If you advance your timing a little see if it fixes it.

You will probably want to consider a aftermarket ECU, as the S4 ECU is not really set up to run a S5 motor.
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Old May 22, 2006 | 11:24 AM
  #7  
DREYKO's Avatar
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I "lost" my emissions....
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From: lillington, nc
ok cool thx icemark
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Old May 22, 2006 | 01:35 PM
  #8  
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From: Rohnert Park CA
the other reason you could be rich (but its a reach- just guessing here) is if fuel rail pressure was low, in theory the injector's spray pattern could be sputtering instead of of spraying.

But I don't know how low the rail needs to be to have that happen and if your fuel rail is running at 50 psi it is plenty high anyway. I am assuming that you are checking the rail pressure with the engine running?
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