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Discussion Starter · #1 ·
Ok, I’ve read all the posts on this, and I still have questions about fuel delivery. My jeep has 5/16 fuel lines coming up the frame, then they couple to rubber lines up to the fuel rail. When I put the 4BT in, I’d like to just put a bypass regulator in on my fuel line, and an extra return line for it back to the tank, then continue to use the stcok fuel pump in the tank. In my thinking this makes up for not being 3/8, as the pressure will still be there, but will the volume? My plans for now are to keep the engine in its stock form (performance wise). Then once it’s in, and all the bugs are gone, I can add all the fancy stuff.
 

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That would work provided you fuel line pressure at idle does not exceed 20 psi.
If it exceeds 20 psi then you need to toss out the in tank pump and the regulator.
 

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From memory it somewhere normally around 10 - 12 psi maximum at idle to 4 psi minimum at wide open throttle using the OEM lift pump.
 

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You could use an Aeromotive 13301 fuel pressure regulator to get your EFI pump down to a normal psi. You can keep the stock supply line with one of those. I would try it with the stock return line first, and if you can't get the pressure down to 10 psi then the next size larger line would be needed for return.

Are you keeping the stock lift pump??
Then you only need to get fuel "up to" the lift pump (even at 0 psi) with a small header tank, and the tank can be full bypass.
 

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Discussion Starter · #6 ·
Quote:

You could use an Aeromotive 13301 fuel pressure regulator to get your EFI pump down to a normal psi. You can keep the stock supply line with one of those. I would try it with the stock return line first, and if you can't get the pressure down to 10 psi then the next size larger line would be needed for return.


Your saying use the stock return line for the requlator, as well as the injector pump? The line won't be overloaded?
 

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Your saying use the stock return line for the requlator, as well as the injector pump? The line won't be overloaded?

I highly doubt it. Only thing is diesel is a bit thicker than gas, but if your factory return line is 1/4" it should be fine.

Try this: hook the supply and return lines together with a T and put a pressure gauge on the T.

Drain the gas, add the diesel, then run the EFI pump (may have to jumper the relay)

If the gauge is 15 psi or less, you are almost done. Unscrew the gauge and run a fitting to the inlet of the lift pump (LP). The return (Rtn) on the Cummins will need to be a little farther downstream, so any air bubbles will get pushed back to the tank and not get sucked up by the lift pump.

 
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