Fuel Course
Thread Starter
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Joined: Dec 2021
Posts: 97
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From: Atlanta GA
Fuel Course
Good Afternoon, I am confused and seeing contrasting information.
on 1985 C4, Does fuel flow from the tank first to the FPR and then the rails or does fuel flow to the rail and then the FPR. I am not understanding the direction of flow.
And: is the fuel filter on the rail part of the return line or the fill line??
Thank you.
C
on 1985 C4, Does fuel flow from the tank first to the FPR and then the rails or does fuel flow to the rail and then the FPR. I am not understanding the direction of flow.
And: is the fuel filter on the rail part of the return line or the fill line??
Thank you.
C
Last edited by Charles212; Jan 23, 2022 at 04:56 PM.
Burning Brakes
Joined: Apr 2014
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The pump sends fuel to the rail first. The regulator has a spring loaded valve. The excess pressure that the pump develops overpowers the spring in the regulator. The pressure bleeds through the regulator valve sending fuel back to the tank.
Thread Starter
Advanced
Joined: Dec 2021
Posts: 97
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From: Atlanta GA
So is the fuel filter then on the fill line or the return line back to the tank. I have seen it noted that it is part of the return. I had made the assumption that it was on the Fill. Which is true?
Drifting
Joined: Jan 2021
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From: Northern California
It is always on the Fill. The post you are referring to mentions another (second) filter on the return line on some cars only. On the TPI cars, the rails and the injectors get the fuel first, then the excess goes out of that gray pipe that exits the fuel pressure regulator (bolted on top of the rail). That is the return line.
