Vacuum lines

690 Views 7 Replies 3 Participants Last post by mercenvy_3114, 10 d ago

55 F100

Discussion Starter · 17 d ago

HI- I have a 4.6 from a 98 Mark VIII. I have deleted the EGR from the ECM. Can anyone provide a "Down and Dirty" Vacuum line diagram? The Intake has 2 ports on the rear and 1 under the throttle body. The PCV valve on drivers side splits into 2 ports on the top of the intake. Not sure if I need to just cap off the 2 rear and throttle body ports. Thanks in advance.

Hood Motor vehicle Blue Automotive fuel system Automotive design

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mercenvy_3114

· #2 · 16 d ago

You'll need a vac line to the FPR.

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mercenvy_3114

· #4 · 13 d ago

I don't think the stock 98 ECM has provisions to run a returnless system. Any particular reason you want to go returnless? That sounds needlessly complicated to me, just imho.
Stock 98 fuel rail doesn't use check valves as far as i know. There is a factory vacuum harness that splits and connects to both sides of fuel rail.

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mercenvy_3114

· #8 · 10 d ago

I ditched my Markviii ecm in favor of Holley Terminator X and could not be happier.
Like you said- i did it so i can just drive the dang car. Which is exactly what i do now lol.
Install was easy but i did already have the return style system

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