Weird Fueling Issue

[Member5167]

Okay so here's the scoop. I couldn't find ANY other forum with the same issues going on here. I'm having an issue at idle making only tank pressure (60-70psi). Once the car goes over ~2k rpm the hpfp pressurizes the fuel to ~1600-1700psi . Car is throwing a p0089 code. You can't hear the spill valve ticking below 2k. Now I put 3 other hpfp's on the car and same issue with ~2k rpm kicking on. I replaced the hprv, internals, cleaned spill valve, and checked all the grounds. The only thing I haven't replaced is the FP sensor and that still reads fuel pressure. Kind of stuck with it and need some help. Thanks in advance.

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Okay so here's the scoop. I couldn't find ANY other forum with the same issues going on here. I'm having an issue at idle making only tank pressure (60-70psi). Once the car goes over ~2k rpm the hpfp pressurizes the fuel to ~1600-1700psi . Car is throwing a p0089 code. You can't hear the spill valve ticking below 2k. Now I put 3 other hpfp's on the car and same issue with ~2k rpm kicking on. I replaced the hprv, internals, cleaned spill valve, and checked all the grounds. The only thing I haven't replaced is the FP sensor and that still reads fuel pressure. Kind of stuck with it and need some help. Thanks in advance.

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[Member5167]

Bump.

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[Member5167]

Below is it running.20191003_164801.mp4

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[MSMS3]

https://corksport.com/blog/hpfp-troubleshooting/

I lean toward the spill valve stuck open. I know you cleaned it, though. Maybe check it’s connection, too.

Second level of diagnosis is to remove the hpfp, disassemble, thoroughly clean with brake cleaner, inspect for damage, scoring, wear, and if ok, lube and reassemble. You must do this under very clean conditions, as contamination can really mess it up. Tolerances are very close.

But, you’ve swapped pumps, with no improvement, so this is puzzling.

Could you have damaged the wiring or connectors? Look for frayed or damaged wires on either the plug end or at the ECU harness plug end.

[Member5167]

Okay I checked out the harness. The wiring seems pretty janky. I move it around a little and it'd throw like 10 more engine codes. So I'm going to get a new harness. I used a multi meter to test the wires getting 1.6 ohms from the connector to the ECU. And only measuring the volts at 8.2 when idling so I think the wiring is shot. Would you happen to know where I could get a new wiring harness and not a used one?

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[MSMS3]

Originally Posted by Member5167 Okay I checked out the harness. The wiring seems pretty janky. I move it around a little and it'd throw like 10 more engine codes. So I'm going to get a new harness. I used a multi meter to test the wires getting 1.6 ohms from the connector to the ECU. And only measuring the volts at 8.2 when idling so I think the wiring is shot. Would you happen to know where I could get a new wiring harness and not a used one? Sent from my SM-G965U using Tapatalk

New harness will be a dealer item. Get a part number from your dealer, and then shop that number on eBay. Many Mazda dealers sell discounted OEM parts through eBay.