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Crazy FPR readings


Guest ZmeFly

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Guest ZmeFly

I have a 83 280ZXT, with ic @ 15#'s of boost. I didnt run the car down the road to test this as I was to worried about a line bursting and fuel going everywhere.

 

When I tested the fuel pressure using a know good pressure gauge, I had gotten a reading of 48psi @ idle. When manually reving the engine to about 3-4k rpms, the pressure dropped to about 40psi.

 

The FPR that is on there is the one I got with the car, it is NOT a nissan or aftermarket equilvelant thereof. I dont know what it is off of. My AFPR took a shyte on me so I had to put this one back on.

 

Now correct me if Im wrong but as you manifold pressure approaches a positive point (ie boost) should pressure rise instead of fall?

 

I also removed the vacumn to the FPR with no noticeable change, would this mean that it is bad as well?

 

At least now I know why Im running so rich at idle.

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Guest 81na ZX

It SHOULD be at the lowest point when you make the most vaccum (i.e. idle). It also should raise when ever the vac is lessened/boost made. Example - lets say the FPR is set at 42.5 @ 0psi (no vac line), at idle it sould be somewhere around 35-38 (given a 1:1 rate). At 15psi, you should see 57.5psi fuel.

 

That said, I'd say your FPR is toast.

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