LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Fuel Problem-Despirately Need Help

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Old Mar 7, 2003 | 08:17 PM
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FlyByFormula's Avatar
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From: ks,usa
Fuel Problem-Despirately Need Help

I have a 94 Firebird that is my only car and is my daily driver. I went to start it last week and it nearly started then would simply just crank over and wouldnt attempt to start. I checked for spark and it had spark. I started it with starting fluid and it ran fine. I decided to changed the filter. When i changed the filter, there seemed to be alot of pressure in the lines which leads me to think that the pump was ok. I may be wrong however, b/c i didnt relieve the pressure from the gas cap first. Well, the car ran and started fine all this week until tonight. It again, almost started then acted like it wasnt getting fuel and then just cranks over and will not start. I know this is a fuel problem. I just am not sure how to trouble shoot this. What are the options within the fuel system that this could be? Pump, Injectors (unlikely), fuel line clogged, I am needing suggestions. Is there any type of auxillary pump under the hood or anything that pulls fuel from the front of the car? The reason I ask is that I heard some unusuall clicks when turning the key on. Please help. If this is a bad pump I am goin to have to drive about 5 hours to get to my hometown and get in the shop and change this with my dad. I really need to get this fixed this weekend. PLEASE HELP GUYS!!

Car has 95k miles. Original fuel pump and I think has original opti. But i am not having a spark problem.
Old Mar 7, 2003 | 08:21 PM
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The only way to prove a fuel problem is with a test gauge connected to the fuel rail. The pump may work at times and maybe not other times. When the trouble is present, the pressure needs to be checked.

Normal pressure with the vacuum line off to the regulator should be 41-47 psi. Idle pressure (vacuum line on) may be 3-4 psi or so lower.
Old Mar 7, 2003 | 08:29 PM
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FlyByFormula's Avatar
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From: ks,usa
Shoebox,

Thankyou for the response. Where can I get a fuel pressure guage? I have an OReily's Parts store in town and do you think this is something they would have that I could borrow, or I am goin to have to buy one? How expensive are they, and is there a particular one that I need to buy that will work with my car? Tommorrow I will have to start the car with the starting fluid to get to the parts store, and chances are that it will be runnin ok again for a while. Even if it is starting, yet the pump is on its way out, will I still be getting a weak FP reading to indicate a bad pump? Does this sound like a bad pump to you? Thank you for you help
Old Mar 7, 2003 | 09:10 PM
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"Oh, Reallys" or places like them should have one. Expect to pay ~$35.
Old Mar 7, 2003 | 09:12 PM
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From: Hell was full so they sent me to NJ
The "fuel pressure test gauge" you need will be about $35-40. It has a rubber hose, a -4AN fitting to allow it to attach to the Schrader valve on the fuel line, a pin in the fitting to depress the valve core in the Schrader valve, and a button to release pressure in the lines so you can unhook it.

In addition to checking the fuel pressure, I would also scan the computer. If you are having problems with the optical sensor in the Opti, it will set DTC 16, and when that code is "active" the PCM shuts down the fuel pump and the injectors.
Old Mar 8, 2003 | 11:42 AM
  #6  
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From: ks,usa
Well this morning the car started up. It took a sec kinda like the fuel was right there but it did start. Can anyone give me a pic or diagram that shows me where that schrader valve on the fuel rail is? I can't seem to find it. More and more, this is looking like a failing fuel pump. I dont think think my computer is throwing that code b/c when it wasnt starting I checked for spark and had it. Thanks for all the help.
Old Mar 8, 2003 | 05:31 PM
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Shoe's guide! It and he has helped me!

http://csce.uark.edu/~jgbertr/rb/fue...ader_valve.jpg
Old Mar 9, 2003 | 07:32 AM
  #8  
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From: Hell was full so they sent me to NJ
Or from the back:

Back of Intake

Yours won't have the 90-degree fitting on it... just a black plastic cap.
Old Mar 13, 2003 | 11:25 PM
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From: Wichita, Ks, USA
Thumbs up

Thanks for the pictures guys, you really helped me too !

Weather is warming up out here, so I'm getting ready to change the fuel filter and would like to release the fuel pressure first.

The Haynes manual I have shows a picture with an arrow pointing to the area on the LH side of the fuel rail/intake manifold to indicate the schrader valve position. I looked all up and down the LH side of the fuel rail for a schrader valve to no avail.

Did a couple of searches and found this thread. Your pictures nailed it.

You guys are cool, and so is this board !

Brad
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