EFI Sending Units

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Bama69

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87 v10 4wd - I’m currently running the stock 350 with TBI. In the near future plan on replacing it with a 383 stroker with EFI. I need to replace the sending units and wondering if I can run the TBI with a higher fuel flow sending unit that will be needed for the EFI? If so, are there any other mods I would need to make such as fuel lines, fuel filter, dual tank valve, etc.?
 

Ricko1966

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You just change the pump and screen. An Ep381 will probably due it. But you'll need to compare what your EFI wants VS. What an EP381 can provide.
 

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Yeah, people upgrade to the TBI sending units for their high pressure EFI swaps that require high pressure pumps. You just need pumps for the sending units you already have.
 

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Yeah, people upgrade to the TBI sending units for their high pressure EFI swaps that require high pressure pumps. You just need pumps for the sending units you already h
I really haven't dealt with fuel systems, but would like to eventually, switch things to EFI; but I don't want to do it in all one step. So, I could add the pump to the sending unit in my old tanks (put them in the new baffled tanks I have). My 85 k10 runs a Quadrajet. I know I would have to add a regulator down the line and probably swap out the selector for highpressure..
 

Bextreme04

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I really haven't dealt with fuel systems, but would like to eventually, switch things to EFI; but I don't want to do it in all one step. So, I could add the pump to the sending unit in my old tanks (put them in the new baffled tanks I have). My 85 k10 runs a Quadrajet. I know I would have to add a regulator down the line and probably swap out the selector for highpressure..
I have used an EFI sending unit and just cut off the end of an older carb sending unit that the filter attaches to. You can use the short section of fuel line that would connect the pump to the sending unit and instead use it to connect the end with the fuel sock on it to continue to use the carb pickup, while having the future capability to connect an EFI pump when you are ready. I have also had an EP 381 in my tank for almost a year while still drawing through it with my mechanical pump. I just don't have the wires hooked up to the electric pump. When its hot and I'm pulling a load the added restriction will cause it to start to vapor lock, but just normal daily driving it works fine.
 

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I would think that a TBI tank and sending unit with a TBI pump and a bypass regulator could feed a performance carb type setup, but isn't really needed if you have a mechanical pump that works. I would say that an in tank TBI pump would beat an external fuel pump any day for longevity and consistency. Drawing through a dead TBI sender as discussed above works too, but doesn't gain anything. If, however, you need to overhaul the fuel system anyway, then yes, running an 87+ sender, selector, lines, filter, etc can all be a reasonable step that can work with the current setup and be ready to switch to high pressure pump for EFI in the future.

For reference, the fuel flow of a carb vs TBI vs modern EFI really isn't that different by itself, I just depends on HP of the engine and if you are running a bypass regulator or not. The Pressure is what changes. Carbs run from 2.5-6.5 psi or so (just a general range, but it is single digits), TBI runs around 12 or so and may deadhead the pump at 25 or 30 psi, and "EFI" runs around 50 psi. Direct injection is a different animal, you feed the engine ~50 psi and the internal pump brings it up to 2-3000 psi or more, but no one runs those high pressure lines, they are part of the engine for all intents and purposes.
Most carb rated fuel lines and barb fittings top out around 10 psi as far as wanting to run at that pressure. The early TBI stuff was over the rating for typical fuel lines, so it was engineered and rated for up to 200 psi, really overkill but it made everyone feel much better about the "high pressure" fuel lines. Modern stuff is still rated for a lot more than we throw at it, still around 200 psi ratings. And that is definitely overkill, 200 is the service rating for nylon tubing, for instance, the failure rating is over 1000 psi, so we have safety factor on top of safety factor.

In short, unless you are going crazy, 87+ fuel lines and filters etc is all you ever need, and can be run on carb setups as long as you are aware of the minor stuff to hook it up correctly.
 

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