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91 Camaro THROTTLE BODY PROBLEM


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thirdgennewie
User

Sep 26, 2009, 8:57 PM

Post #1 of 22 (7808 views)
post icon 91 Camaro THROTTLE BODY PROBLEM Sign In

91
chevy
camaro
5.0
87k

Hey , I Just purchased a 91 camaro rs 305 and when I start the car it runs for a couple seconds and then alot of fuel dumps on the top on the two butterfly valves that open when you start the car and it makes a hissing noise like air is coming out thats loud, and the car shuts off but when i started it another time the fuel wasnt spraying as much and the noise was not there.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 27, 2009, 5:31 AM

Post #2 of 22 (7797 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

Your having a problem with the overfueling for some reason. The hissing noise is just the idle air control opening up trying to overcome this. This could be bad injectors, computer, related wiring or other things. You need to use a professional scan tool to examine the sensor data to give you a hint of what is going on. This may not even be the injectors doing this. The fuel pressure regulator is built into the throttle body and that could be leaking. Try unplugging the injectors and see if the fueling stops then.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Sep 27, 2009, 5:33 AM)


thirdgennewie
User

Oct 1, 2009, 8:53 PM

Post #3 of 22 (7772 views)
post icon Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

I replaced the injectors and still the car is having trouble turning on and once it drives its like its gasping for fuel but I was wondering if it could be the fuel filter instead of th epump since the car is still turning on .

thanx guys


Hammer Time
Ultimate Carjunky / Moderator
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Oct 2, 2009, 2:32 AM

Post #4 of 22 (7769 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

Why did you change the injectors? Nobody ever suggested that. No, the fuel filter won't cause that.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



thirdgennewie
User

Oct 20, 2009, 4:57 PM

Post #5 of 22 (7725 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

ok ive changed the injectors, fuel filter ,I also tested the fuel pressure an got 8pci's.....? and discovered some vacum leaks but the car is still doing the same thing it will run for about an hour an start to shut off while driving or stopped if you have any suggestions please help. thanx


Hammer Time
Ultimate Carjunky / Moderator
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Oct 20, 2009, 5:06 PM

Post #6 of 22 (7721 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

If your saying that your fuel pressure is 8 PSI, then there is a problem. The spec is 9-13 and I'm sure yours gets even worse at times. Get your fuel pressure resolve first.

You could have a regulator leaking in the throttle body.


The pressure regulator is an integral part of the fuel meter cover, and contains an air chamber and a fuel chamber that are separated by a diaphragm-operated relief valve and a calibrated spring. The function of the regulator is to maintain constant pressure across the injector at all times.fuel pressure is regulated by the difference between fuel pump pressure acting on one side of the diaphragm and the force of the calibrated spring (and air cleaner pressure) acting on the other side. The system operates in an acceptable pressure range of 62 to 90 kPa (9 to 13 psi). The fuel meter cover includes a bleed that relieves system pressure when the engine is turned "OFF". The bleed also helps purge vapors from the injector and regulator after a hot restart.
If the pressure regulator in the TBI supplies pressure which is too low (below 62 kPa or 9 psi), poor performance could result. If the pressure is too high, excess emissions and unpleasant exhaust odor may result.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Oct 20, 2009, 5:16 PM)


thirdgennewie
User

Oct 20, 2009, 5:21 PM

Post #7 of 22 (7710 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

 yes I got 8psi's and fuel pressure resolve?? could it be the pump ? I went to carx and they said i need a new distributor, erg sensor, and map sensor???


Hammer Time
Ultimate Carjunky / Moderator
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Oct 20, 2009, 5:24 PM

Post #8 of 22 (7708 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

How are any of those things pouring fuel into your throttle body?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



thirdgennewie
User

Oct 20, 2009, 5:34 PM

Post #9 of 22 (7703 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

they arent, its either the fuel pressure regulator or the pump then right?


Hammer Time
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Oct 20, 2009, 5:38 PM

Post #10 of 22 (7702 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

The pump isn't going to do that either, especially with the low pressure reading. I would pinch off the return hose or the pressure hose after your gauge and check the pressure again. If it spikes up then, the pump is fine. If you can't get any readings over 15PSI, then the pump may be bad. Otherwise, I'd concentrate on the throttle body where the regulator is.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



thirdgennewie
User

Oct 20, 2009, 5:40 PM

Post #11 of 22 (7695 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

how do i test to see if its the regulator??


Hammer Time
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Oct 20, 2009, 5:45 PM

Post #12 of 22 (7689 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

Pinch off the return and see if the pressure bleeds off when shut off. If it does, also pinch off the pressure line before the gauge after shut off to see if it stops the bleeding. If it still bleeds with both lines pinched off, the regulator has to be leaking.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



thirdgennewie
User

Oct 20, 2009, 5:45 PM

Post #13 of 22 (7686 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

which line is the return line ? or pressure hose? and where do you pinch it off?


thirdgennewie
User

Oct 20, 2009, 5:49 PM

Post #14 of 22 (7684 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

should the pump constantly hold pressure after you turn the car off when testing the fuel pressure? because it went back down to zero when i turned the car off


Hammer Time
Ultimate Carjunky / Moderator
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Oct 20, 2009, 5:49 PM

Post #15 of 22 (7682 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

I don't know how your checking fuel pressure if you don't know the pressure line from the return.

The pressue line is the larger one. You want to isolate the tank on both lines.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



thirdgennewie
User

Oct 20, 2009, 5:53 PM

Post #16 of 22 (7674 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

I tested it going out of the fuel filter to the throttle body


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 20, 2009, 5:54 PM

Post #17 of 22 (7671 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

That would be the pressure line.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



thirdgennewie
User

Oct 20, 2009, 5:57 PM

Post #18 of 22 (7665 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In


In Reply To
which line is the return line ? or pressure hose? and where do you pinch it off?


which line is the return line ? where and how do you pinch off the return line?

do I have to discoonect it from the throttle body?

Thanx in advance


thirdgennewie
User

Oct 20, 2009, 6:21 PM

Post #19 of 22 (7663 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

which is the return line?? and where and how do I pinch it off?? thankyou for you help and patience


thirdgennewie
User

Nov 10, 2009, 11:08 AM

Post #20 of 22 (7612 views)
91 Camaro THROTTLE BODY PROBLEM Sign In

OK so ive changed the pressure regulator and the car still is turning off and giving me no starts but with the help of some starting fluid spray or throttle body cleaner she starts up eventually, if you have any advice it would be greatly appreciated..thank you


thirdgennewie
User

Jan 19, 2010, 1:19 PM

Post #21 of 22 (7483 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

Does anyone know where the oil pressure sending unit is on a 91 camaro??

any help is greatly appreciated thanks


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 19, 2010, 4:40 PM

Post #22 of 22 (7476 views)
Re: 91 Camaro THROTTLE BODY PROBLEM Sign In

  • Sending unit
  • The Oil Pressure Switch is located: Under vehicle, driver side, below engine area, center of block, mounted above oil pan flange
    Application:
    Sending unit

    *************** That's what a parts outlet says, T







     
     
     






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