EFI conversion clarification

[Amanandhistruck]

Evening everyone! So I've recently purchased and mocked up my Fitech 600HP EFI throttle body to my 1987 GMC K15 with a 383 stroker. My question that I need clarified is with my dual tank system that I still want to use. My plans are to incorporate Hyperfuels Retro Fit pump;however,I've been getting conflicted information from social media forums on how to route/retain the rest of the system. From what I'm gathering,1987 is the first year they began incorporating TBI with some of the components,so does that mean I can just Piggyback off the existing "plumbing" and dash switch once the Hyperfuels are installed? Any clarification will be greatly appreciated.

 

[Bextreme04]

Evening everyone! So I've recently purchased and mocked up my Fitech 600HP EFI throttle body to my 1987 GMC K15 with a 383 stroker. My question that I need clarified is with my dual tank system that I still want to use. My plans are to incorporate Hyperfuels Retro Fit pump;however,I've been getting conflicted information from social media forums on how to route/retain the rest of the system. From what I'm gathering,1987 is the first year they began incorporating TBI with some of the components,so does that mean I can just Piggyback off the existing "plumbing" and dash switch once the Hyperfuels are installed? Any clarification will be greatly appreciated.

Was your truck TBI already? If so, and you already have dual fuel tanks, you shouldn't have to change anything. I think you would already have dual electric fuel pumps, one in each tank... right?

 

[Frankenchevy]

Aftermarket efi requires 58ish psi, tbi is ~10-12psi. No, factory tbi pumps won’t work, but factory vortec pumps mounted to tbi senders in tbi tanks will.

You will need efi rated lines and fittings that are rated beyond 60psi as well.

The question is, will the factory tbi switching valve handle the psi?

the other option is the remote sump mounted in the engine compartment, where the factory tbi pumps supply the sump with fuel and a sump pump supplies the required psi.

 

[Amanandhistruck]

How can I confirm if it was or not? It was an original 5.7 truck,as the label is still on the core support,but not sure if it was a true TBI.

 

[Bextreme04]

Did you not have the engine in it? I mean, you should be able to just look at the truck and tell if it is TBI or carbureted.. unless a previous owner ripped out the TBI

 

[Amanandhistruck]

The engine was missing the intake when I purchased it,and I'm not sure if its the original motor,haven't verified numbers yet,but it is a 5.7 block.

 

[Bextreme04]

The engine was missing the intake when I purchased it,and I'm not sure if its the original motor,haven't verified numbers yet,but it is a 5.7 block.

According to the 1987 Truck brochure, all 1987 trucks with gasoline engines had EFI. https://www.gmheritagecenter.com/do...its/Chevrolet-Trucks/1987-Chevrolet-Truck.pdf

 

[Amanandhistruck]

Awesome. I've heard the switch can handle up to 65psi,but no way to confirm,that's why I'm asking yall,the experts. So that being said FrankenChevy,I can use the Hyperfuel to boost PSI which will also give me my return hook up in one package,I would just have to upgrade the fuel lines to stainless nylon and AN fittings. Am I understanding correctly?

 

[Frankenchevy]

Awesome. I've heard the switch can handle up to 65psi,but no way to confirm,that's why I'm asking yall,the experts. So that being said FrankenChevy,I can use the Hyperfuel to boost PSI which will also give me my return hook up in one package,I would just have to upgrade the fuel lines to stainless nylon and AN fittings. Am I understanding correctly?

I'm not familiar with that system in particular. I just put vortec era pumps in tank (deco ep381 or Delphi fe0114, I'm not 100% certain on the Delphi number)

if the system you're referring to is a sump system under the hood--only the lines going from the sump to the efi and from the efi back to the sump need to be high pressure rated. The stuff from your tanks to the sump itself just needs to be intact, but not necessarily high pressure. I think J30r9 is rated high enough for factory tbi, but just ask the parts store guys for something higher than whatever pressure is on the circuit.

 

[Amanandhistruck]

Another option at least,thanks! And hyperfuel is basically a higher PSI fuel pump you install in you're factory tank via a secondary access point. Pur factory PSI is what,43-47 PSI? Fitech needs 58PSI to run efficiently. Another bonus with Hyperfuel is that it has a higher PSI pump (90 PSI),filter, return,vent,and feed connectors already part of the assembly. The old sending unit stays electronically attached only as a fuel level gauge.

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There are alot of issues with the Surge tanks,FCCs,and inline pumps. Thinking this route would be more reliable. I'm just not used to incorporate a second tank set up controlled by one switch I guess,or see the apparent difference with my 87 being a prior TBI truck from factory. Thats where I'm lost.

 

[Kasey 1977 K10]

Evening everyone! So I've recently purchased and mocked up my Fitech 600HP EFI throttle body to my 1987 GMC K15 with a 383 stroker. My question that I need clarified is with my dual tank system that I still want to use. My plans are to incorporate Hyperfuels Retro Fit pump;however,I've been getting conflicted information from social media forums on how to route/retain the rest of the system. From what I'm gathering,1987 is the first year they began incorporating TBI with some of the components,so does that mean I can just Piggyback off the existing "plumbing" and dash switch once the Hyperfuels are installed? Any clarification will be greatly appreciated.

Take a look at thread #27 on https://www.gmsquarebody.com/threads/tank-replacement-for-efi.24131/page-2#post-472294. It would be far less work for you given you have the '87 pluming already but it does have details about the pumps, sending units, switch and selector valves.