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post #1 of (permalink) Old 12-11-2000, 09:31 PM
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External EFI fuel pumps - need to prime??

Hey folks. I temporarily wired up the computer on the 4.3L tonight to check out the fuel pump operation and flush the supply line. The pump cycles on for 2 seconds and shuts off correctly. However, after multiple cycles, I still haven't seen any fuel from the supply line.

Any of you who've done a EFI conversion and running a external pump, did you have any issues getting the pump to draw fuel from the tank?

Jim O'Brien
[email protected]
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post #2 of (permalink) Old 12-11-2000, 10:19 PM
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Re: External EFI fuel pumps - need to prime??

When I put the Howel TBI on my jeep, I did not prime the fuel pump. The pump is mounted on my frame. When I started it up, I disconnected the fuel line from the TB until I got fuel flow, that took some time. Connected it all back and it started right up.


post #3 of (permalink) Old 12-11-2000, 10:38 PM
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Re: External EFI fuel pumps - need to prime??

The pump needs to be primed! these pumps are dot designed to "draw" fuel, they should be mounted as low as possible on the frame, so that the fuel tank floods the inlet of the pump. On initial start up you should let the outlet of the pump drain into a small gas can while a small amount of air is pressurizing the tank, this will get the pump to draw the air out of the supply line.
I do not know if these pumps will burn up if run dry, but I was involved in retrofitting a bunch of USAF C-135 aircraft because the fuel pumps would cause a fire if the crew left the pump running in an empty tank. I know that about 7 Air National Guardsmen died in one of those incidents. Just something to think about...Safety First

good luck, jjc

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post #4 of (permalink) Old 12-12-2000, 10:47 AM
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Re: External EFI fuel pumps - need to prime??

I had the same result as mike84CJ7. Never primed the pump and my Howell setup fired on the first try.

'75 CJ5,258 w/Howell EFI,T18a,4.27's,33's,On-board air,Warn 8274
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