Fuel pressure

Recently did a full Terminator swap into 03 GT, all harnesses transferred, nothing cut/spliced. Car idles and runs fair but I am experiencing some 2196/2197 rich condition as well as weird spikes in fuel pressure. Key on engine off initial prime will read anywhere from 40 to sometimes as high as 80psi verified on scan tool and at rail with gauge. Have tested and swapped fuel rail pressure regulators and no change. Pumps are new stock precision pumps. All culprits generally responsible for rich condition checked. O2s sweeping as they should. Everything in car is stock, Ecm stock, was bench tuned and had what tuner described as E10 Tune loaded into it. At this point I am leaning towards swapping the pumps, but am wondering about the tune. All thoughts are appreciated. Anyone ever experience anything like this?

What are the specs of the bench tune? If the pumps are hitting 80psi I don't think they're an issue. Usually they lose pressure. It sounds like a fuel pump control issue to me.

I got nothin on the specs of the tune other than what he called it. An E10 tune. I asked him about that but of course he didnt think the issue was in the tune at all.

If the car idles and runs fair I would say the tune needs work I would datalog and go from there. If something mechanical is going on usually a good datalog will uncover something.

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All harnesses including body, dash ect? Computer Pins and body harness pins are not the same from cobra to GT. What you think the computer is reading might not actually be what the computer is reading.

My buddy bought a bastardized cobra swap that took us months of fixing to get right. We started doing the harness swaps and hit a dead end. You need literally every harness, computer ect out of a cobra or it's not worth doing it that way. Converting a GT harness to run a cobra motor is very easy and straightforward.

Thanks guys. All input is appreciated. I think my first step will be to have the base tune loaded back into it and go from there. @ 03 White Snake. All harnesses were transfered from front to back. After doing so though I figured out the only ones that were really needed were the dash, ecm, battery and engine harness. I am pretty positive the body harness between the 2 are ok. Out of curiosity. Are you guys running a factory ecm or standalone? Am thinking of switching to standalone.

If the pump tables weren't tuned to match the new, bigger pumps, it could be commanding too much fuel, resulting in a rich condition. The incredibly high pressure spikes on prime suggest that could be possible. It might need some fine tuning of those tables.

Regarding the ECM the factory one worked pretty damn well. I'm switching to a standalone for the boost control, traction control, more versatile limiters, and flex fuel capabilities that the stock ECM doesn't offer. All of which you can live without, but I've reached the point I could really use them.