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Need help with 85 Firebird

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Old Apr 1, 2024 | 08:07 AM
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Need help with 85 Firebird

Hello all! New to this forum but not new to forums. I was surprised there was still one alive to be honest! This site kept coming up for every google search I was doing so I figured I would give it a try. The car I am working on is not my car. It is my uncles and it started off that I was going to be just redoing all the interior and well here we are. I am not very well versed in these cars so please ignore my ignorance if you would.
My uncle bought this car new in 1985. This was his first car and he loves it. He had someone repaint the car and then he had someone rebuild the engine. The car has been sitting for probably 10 years with the fresh paint and new engine without being ran.

This car came to me with no tank in the car but a new tank, pickup/sending unit assembly, and new in tank fuel pump. (I know most of you can probably already tell what my problem is from this information.) I installed the pump and installed it in the tank. I then went about trying to find all the parts. I managed to find all the pieces to include all of the hardware. I started to install the tank when I noticed that I only had 3 lines on the car and 4 on the tank. I quickly understood one of them was going to be the fuel tank vent. (Thanks to this site) The part I could not figure out was the one threaded line on the tank and none on the car. I then pop the hood to discover a Quadra jet carb and a mechanical pump on the side of the block. So it would appears to me that he has ordered a 86 or newer drop in with pump for an 85 model car. I am sure he has had these parts long enough that he will not be able to return them. My question is what would you do in this situation? Do we just order the correct drop in or do we remove the mechanical pump install a block off plate and install all needed lines? Also, to easy your minds. I will replace the mechanical pump with a new one if that is the route we go. Who knows how old it is and I ruined a perfectly good 400 small block when I was young and dumb because of this. Thanks in advance for any help you can offer!

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Old Apr 1, 2024 | 07:13 PM
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Re: Need help with 85 Firebird

Oh we have heard about the double fuel pump scenario....

Keep in mind that quadrajets use only a few psi of fuel pressure... Too much and the float cannot hold the needle in the seat.... But the TPI engines use 40 psi.... So it's not just one or the other.... It's the right one.

I had an 85z for years... And it had a mechanical pump to feed the quadrajet... And I never found the right pickup for the tank.... Everyone wanted to sell me the fuel injection version.... But maybe that one works somehow???

Every quadrajet I have owned used a mechanical fuel pump with standard pickup.... 3 pipes... Supply, return, vent...these all go to the engine compartment. But the fourth is the fuel tank vent valve... Because these cars do not use a vented fuel cap ... To control emissions. The vent valve is mounted on the body forward of the rear axle. A bracket is welded to the body.... I can try to get a pic if you need it....
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Old Apr 2, 2024 | 06:45 AM
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Re: Need help with 85 Firebird

Thanks for the reply. Sounds like I need to figure out a way to convert the pickup he bought to a normal pickup and get rid of the intank pump. Anyone here done that?
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Old Apr 2, 2024 | 11:48 AM
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Re: Need help with 85 Firebird

I don't know anything about converting a FI sending unit but the carbed versions are available -

https://www.ebay.com/itm/25584174025...Bk9SR4jqnvvTYw
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Old Apr 2, 2024 | 06:45 PM
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Re: Need help with 85 Firebird

Nice that they are finally available..... Nice and expensive.... !

But there is the answer!
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Old Apr 2, 2024 | 07:13 PM
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Car: 1989 Trans Am
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Re: Need help with 85 Firebird

Originally Posted by erik69&85
Nice that they are finally available..... Nice and expensive.... !

But there is the answer!
Yeah, I only paid a little more for my Aeromotive hanger with fuel pump than what they are asking for that carbed one. But, specialized parts that only fit certain years of cars getting reproduced probably isn't cheap.
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Old Apr 2, 2024 | 09:03 PM
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Re: Need help with 85 Firebird

'Figures it would be expensive..
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Old Apr 3, 2024 | 03:38 PM
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Re: Need help with 85 Firebird

Thanks all for the replies. I will let him know and see what he wants to do. I have a filling he isn't going to want to spend the money on a whole other setup after buying the pump and wrong one. He is going to ask me to make it work some how. Before I go to him you think anyone would be interested in this setup at a discounted price?
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Old Apr 3, 2024 | 09:01 PM
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From: SW Missouri
Car: 1989 Trans Am
Engine: sp357
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Re: Need help with 85 Firebird

Originally Posted by Greymare
Thanks all for the replies. I will let him know and see what he wants to do. I have a filling he isn't going to want to spend the money on a whole other setup after buying the pump and wrong one. He is going to ask me to make it work some how. Before I go to him you think anyone would be interested in this setup at a discounted price?

Your other option is to block off the mechanical pump and wire up the FI pump into a fuel pressure regulator down to the fuel pressure you need. Probably spend as just much $$$ doing that vs getting the correct carb pickup/sending unit and rigging all that up plus the time to do all the wiring though.

Post the one you have on hand in the classifieds board, someone might be looking for one.
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Old Apr 4, 2024 | 12:48 PM
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Re: Need help with 85 Firebird

Is the car an H.O. model? High Output 5.0, those engines used both mechanical and electronic fuel pumps.
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Old Apr 4, 2024 | 03:21 PM
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Re: Need help with 85 Firebird

Originally Posted by 84 1LE
Is the car an H.O. model? High Output 5.0, those engines used both mechanical and electronic fuel pumps.
Not an HO. Just called and broke the news to him. I am waiting to see what he wants to do. Hope he just buys what we need. LOL
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Old Apr 4, 2024 | 08:42 PM
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Re: Need help with 85 Firebird

Could a TBI in tank pump be used or would a regulator still be needed?
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Old Apr 4, 2024 | 09:13 PM
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Re: Need help with 85 Firebird

Probably still need the regulator. Carb psi is around 8lbs.
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