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Old 05-08-2016, 03:48 PM   #1
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Question Fuel Problem.. help

Hi Everyone.
First off, I've been using the forum as a tool for a long time but i can't seem to find what i need so this is my first post. A little about my car... its a 90 GT that i recently had the motor out of the car over the winter because compression was weak on my #6 cylinder. i went through the bottom end and while i was there i figured id mildly build the top end... So here are my mods. TFS stage 2 cam, TFS 170 heads, Holley Systemax II upper and lower intake, 24# injectors, 70mm throttle body, BBK fuel rails, long tube headers,24# MAF to match injectors, and I'm sure there is more I'm forgetting but those are the basics.

Here is the problem I'm experiencing. While priming the fuel pump I'm getting a loud hissing sound coming from what sounds like the passenger side rail. i just haven't been able to pinpoint exactly what is happening. I originally thought it was my new Kirban AFR so i exchanged that for another one...no luck.. I then Changed out my 24# injectors for my old stock 19# and again no luck.. I've sealed all threads of the fuel rail with either thread sealant or teflon tape-i don't believe there is a leak anywhere.

I bought the Systemax upper/lower intake used so I'm at the point where I'm asking myself, could that cause this type of problem?

Has anyone had a similar problem? i don't have the upper intake on, because i want to straighten this fuel problem out but when i would start my car it would idol nicely until i shut the car down. If i tried to start it back up it wont start unless i bash the gas to the floor..

Hopefully that is enough info to go off of. If anyone has any ideas please let me know

Chris
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Old 05-09-2016, 07:26 AM   #2
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Is the sound I'm hearing while priming just the sound of the regulator functioning?


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Old 05-14-2016, 01:19 PM   #3
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If you floor the gas pedal,while cranking,and that allows the engine to start,youve got an engine flood condition occurring.When you floor the pedal, during crank mode,the ecm shuts the injectors off.Once the excess fuel has cleared out,that allows the engine to start.The flooded condition is usually caused by either a leaking fuel pressure regulator or leaking injector(s).
Let the engine idle & remove the vacuum line from the regulator.Does the line have fuel inside of it or is fuel seeping out of the regulator vacuum port??
If yes,the regulator is defective.
If no,do this test::
1)Connect a fuel pressure gauge to the Schrader valve
2)Turn the koeo
3)Record pressure
It should be 30-45psi.
4)Turn key off
5)Wait 60 seconds
6)Record pressure again
Did pressure drop more than 5psi in that 60 second time period??
If yes,do this test::
1)Pinch a soft section of the fuel return hose off using vice grips(with a rag for hose protection)
2)Turn the koeo
3)Record fuel pressure
4)Turn the key off
5)Wait 60 seconds
6)Record pressure again
Did pressure still drop more than 5psi in that 60 second time period??
If no,the fuel pressure regulator is defective
If yes,youve got 1 or more injectors leaking internally or the fuel supply hose,between the fuel pump & fuel pump pickup assembly (metal bracket that holds the fuel pump) is leaking.
To check for a leaking injector,wait til the no start condition occurs then start removing spark plugs one at a time.Once you reach the plug thats wet with fuel,youve located the bad injector.
The hissing noise you hear is most likely coming from the regulator or injector,depending on which part is bad.
A leaking vacuum hose or leaking vacuum connection could also be causing the noise.

---------- Post added at 01:19 PM ---------- Previous post was at 01:19 PM ----------

If you floor the gas pedal,while cranking,and that allows the engine to start,youve got an engine flood condition occurring.When you floor the pedal, during crank mode,the ecm shuts the injectors off.Once the excess fuel has cleared out,that allows the engine to start.The flooded condition is usually caused by either a leaking fuel pressure regulator or leaking injector(s).
Let the engine idle & remove the vacuum line from the regulator.Does the line have fuel inside of it or is fuel seeping out of the regulator vacuum port??
If yes,the regulator is defective.
If no,do this test::
1)Connect a fuel pressure gauge to the Schrader valve
2)Turn the koeo
3)Record pressure
It should be 30-45psi.
4)Turn key off
5)Wait 60 seconds
6)Record pressure again
Did pressure drop more than 5psi in that 60 second time period??
If yes,do this test::
1)Pinch a soft section of the fuel return hose off using vice grips(with a rag for hose protection)
2)Turn the koeo
3)Record fuel pressure
4)Turn the key off
5)Wait 60 seconds
6)Record pressure again
Did pressure still drop more than 5psi in that 60 second time period??
If no,the fuel pressure regulator is defective
If yes,youve got 1 or more injectors leaking internally or the fuel supply hose,between the fuel pump & fuel pump pickup assembly (metal bracket that holds the fuel pump) is leaking.
To check for a leaking injector,wait til the no start condition occurs then start removing spark plugs one at a time.Once you reach the plug thats wet with fuel,youve located the bad injector.
The hissing noise you hear is most likely coming from the regulator or injector,depending on which part is bad.
A leaking vacuum hose or leaking vacuum connection could also be causing the noise.
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Old 05-17-2016, 04:29 PM   #4
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Thanks for the help. Turns out I was looking at it all wrong. My lower intake wasn't sitting on the heads right so there was an air leak right around cylinder# 3/4. It really did sound like it was coming from the AFR lol


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