Testing Paxton BAP

My car feels like it is running great, and my track logs appear to be good for fueling, but My tuner says my 3rd gear wot pulls to red-line keep showing the O2's trying to add fuel, even after a test tune adding 15% fuel. He's mentioned the possibility of my fuel pump starting to go south.

• A few tests I've tried are
• voltage into bap = 14.17
• voltage out of bap=17.7
• voltage at battery=14.7
• voltage at pump (biggest wire under the driver's side rear seat=10.7)
• everything was car at idle

One of the reasons my track logs might be ok but my 3rd gear logs aren't may be because my track logs were only in the 1/8th mile.

Does all of this seam normal, or do I need to tap into the fuel pump's wire and have my wife floor the car in 3rd until red-line. I'm guessing the harness leading into the fuel hat's plug is still speed controlled somehow, and that's why I'm only seeing 10.7 at the pump??

Also, if this isn't the proper place for the thread feel free to move it accordingly, I just felt it would get the best exposure here.

Also, if it is in fact time to get a new pump, should I just get a new stocker, or what's the best option for my power level with stock motor and about 10psi with the mods in my sig. I can also possibly attach logs, and or do some more testing if anyone has more ideas. Thanks all.

Do you still use closed loop at WOT? I thought the standard was open loop at wot so commanded afr is maintained. is this something different yall coyote guys do since the front 02's are widebands?

Correct the FPCM in the trunk controls voltage to the pump. Its considered a hybrid return-less fuel system as it has aspects of both mechanical and electrical. Max pressure is regulated at the fuel pump outlet on the fuel hat and pump speed is controlled by the pcm via the fpcm.

What bap? are you utilizing stock wiring with a plug and play version? While these new plug and play version are easy to install. The increased current and heat from increasing voltage would still call for upgraded wiring over stock to feed the bap via relay. The more current and heat the pump sees the quicker it will wear out and fuel pumps are wear items, flow rate goes down over time as it wears.

Original fuel filter still? Cheap and easy thing to swap out first.

I'm not sure on the open or closed loop? I also thought I read somewhere that the only fuel filter for Coyote Mustangs was the inlet sock inside the tank, but if there's something in-line, I'll surely do that before replacing the pump.

I also read that the 11 and newer Coyote Stangs had a larger gage wire than previous years that didn't mandate a separate wire to the bap. Currently it is just wired in-line on the harness in the back panel of the trunk.

A 20amp draw on a 14' of wire (guessing this is the distance from the pump motor to the FPCM, and to the power source), calls for a 10awg wire. Some guys use an 8awg wire on their wiring upgrade setups for extra wiggle room. I don't know what the stock wire gauge is on the Yotes but it won't hurt to go bigger.

skaarlaj said:

I'm not sure on the open or closed loop? I also thought I read somewhere that the only fuel filter for Coyote Mustangs was the inlet sock inside the tank, but if there's something in-line, I'll surely do that before replacing the pump.

I also read that the 11 and newer Coyote Stangs had a larger gage wire than previous years that didn't mandate a separate wire to the bap. Currently it is just wired in-line on the harness in the back panel of the trunk.

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Me either for the coyote. Its basicly means using feedback from the 02 to control afr (closed loop) or ignoring it and afr will be as commanded in the tune (open loop).

It does have a larger wire, its 14awg vice 16awg on the 3v as its a higher flowing higher current pump than any previous mustang has had. The 3v didn't mandate it either and guys installed baps without it until a solution was developed. Its counter-intuitive to trying to get more out of your fuel system, the more current the pump motor draws the hotter it runs, which means less flow potential and increased wear. It is still an effective and cheap mod on any car to upgrade the feed wire and improve the health of the setup. 10-12% gain at stock voltage and more on a higher voltage setup with a bap that draws a lot more current than stock. So although you can, I personally would not install a bap or larger pump on any vehicle with out a wire upgrade solution to better handle the higher current level.

The Coyote runs in closed loop at all times except for initial startup, I believe.

I'm sure someone who has actually tuned them can verify if this is true or not. But from watching my AFRs (both banks) on a FRPP tune, that's what appears to be the case.

46addict said:

A 20amp draw on a 14' of wire (guessing this is the distance from the pump motor to the FPCM, and to the power source), calls for a 10awg wire. Some guys use an 8awg wire on their wiring upgrade setups for extra wiggle room. I don't know what the stock wire gauge is on the Yotes but it won't hurt to go bigger.

Click to expand...

It's about 22ft going through all the factory runs. Taking a more direct path gets that down to about 16ft with a dedicated wire. Glad you mentioned distance too, that's another thing you can do, making the wire shorter and thicker both help. I did this on my car years ago as well as the larger wire, I moved the fpdm out of the trunk to just above the fuel hat under the back seat and shortened all the wiring.

Interesting enough to note, Ford eventually did the same thing, 2015+ plus moved the fpcm out of the trunk to under the back seat right by the fuel hat and shortened the wiring.