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Old 03-10-2014, 08:38 AM   #1
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1998 6cta8.3 electric lift pump upgrade

I am going to replace the mechanical lift pump with an electric one that will supply 12 psi @ 150 gph. However, I dont quite understand what I am looking at on the output side of the oem lift pump.

Presently the output of the lift pump goes up to the engine mounted fuel filter with a 1/4" metal fuel line and attaches with a banjo fitting. My concern is that on the same banjo fitting is another 1/8" (black plastic maybe?) fuel line that runs up to all of the fuel injectors. I dont really know what its purpose is, but it looks like it serves as a limp mode fuel line in case the main inline injector pump dies.

My question is if the new electric fuel pump is on whenever the key is on, will the injectors be injecting fuel into the cylinders.

thanks for any insight.

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Old 03-10-2014, 11:01 AM   #2
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The small, fuel return line from the top of the injector to the fuel filter housing , acts as the final pressure bleed at the injector to allow the mechanical injector to close completely/ quickly.
The main injector pump supplies a fuel pressure pulse, in the 2,000PSI range to force the mechanical injector open, then after the line pressure drops as fuel is released into the combustion chamber the internal springs in the injector close the tip and the remaining pressure in the line returns to the filter , so 12 psi will not push fuel into the cylinder.
The return line is metal , painted black, and must be handled with care , kinking it will mess up the whole system.
The spaghetti of twists and turns in the, equal length, fuel lines from the Injector pump to the injectors, is so each high pressure pulse of fuel arrives at the cylinder at the correct time, in relation to every other cylinder.

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Old 03-11-2014, 07:20 PM   #3
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Ahhh thanks very much. I had circled back around as it being a return line verses a limp mode feed line, stare at something long enough right? LOL

Hopefully I can fire it up tomorrow and see how it idles at least. I've decided that using lowe's brass fittings and adapters to try and plumb a fuel system is bordering on rediculous. Too many pieces and way too much money for them.

If this works, I will mount the lift pump up by the tank itself and replace the existing fuel line(s) for something circa now instead of circa late 90's.

thanks for the help.
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