Engine Swap/ECU Removal Electrical Issue

JHuck · Dec 29, 2025

Hello,

I’m a new member/longtime lurker who could use some assistance with my build.

My build started as a 1999 base model. Starting in early 2025, I built a 408W with Promaxx Project X heads, Bullett Racing cam (232/240, 112 sep), Vic Jr, Super Sniper, full length BBK Fox swap headers, Tremec TKX, and full MM suspension front/rear. I swapped in a DW300M in-tank pump, kept the 5/16 fuel line, added an AEM regulator and plumbed in a 6AN return line with a tank bulkhead fitting. I deleted the sound system, rear seat, and moved the battery to the trunk. I have a heavy gauge cable running to the engine and the negative cable runs to a chassis stud that I welded in.

I removed the PCM, associated wiring harness, and the CCRM. The Sniper can handle the fan, AC, and fuel pump.

My current situation relates to the fuel pump/overall power supply. My trunk light, interior light and door chime came on when I connected the battery which I took as a good first sign. When trying to power the fuel pump directly via pin 6 (positive) and pin 7 (negative) in the pump harness, I kept popping an in-line fuse when I touched the positive lead to pin 6. When I disconnected the negative cable from the trunk chassis stud and connected a battery negative lead to pin 7 of the fuel pump harness, the trunk light came back on and the fuel pump ran slowly. This is with no positive connection to pin 6. This has me scratching my head. It appears the pump and lights are picking up a small amount of positive current from the chassis. Any thoughts on this? The draw between my battery cable and the power distribution box is 1.4 amp.

I checked my positive cable and other wires for insulation issues. None found.

95opal · Dec 29, 2025

Sn 95 fuel pumps ran through the ccrm. At this point your better off wiring it into the fuse box with an added relay.

JHuck · Dec 29, 2025

That is my plan. I'm adding a separate fuse box and relays for the fuel pump, AC compressor, and cooling fan. The fuel pump will be triggered by the Sniper blue wire.

JHuck · Dec 30, 2025

I forgot to mention that the pump worked fine when I disconnected both battery terminals from the car and powered the pump with the leads on pins 6 and 7.

JHuck · Dec 30, 2025

I forgot to mention that the pump worked fine when I disconnected both battery terminals from the car and powered the pump with the leads on pins 6 and 7.

JHuck · Dec 30, 2025

I had time today to test a few things. It appears that I wired the aftermarket fuel pump incorrectly so I get to drop the tank again. That would explain why I was popping the inline fuse when I connected the positve lead.

I removed the trunk light bulb and that brought the parasitic draw down to .14 amps. Still high based on what I've seen but I've also read that the system could take longer to fully power down after the battery is reconnected.

weendoggy · Dec 31, 2025

If your new pump only has two wires, you can swap them at the connector. Also make sure the pump is turning the correct way. You can reverse wires and the pump will run, just backwards. It's just an electric motor, but in reverse you get no pressure. I'd install a pressure gauge inline so you know what you have. Not sure the Super Sniper will allow a transducer setup via inputs, but you can add a separate gauge to monitor from the cockpit.

JHuck · Jan 3, 2026

weendoggy said:
If your new pump only has two wires, you can swap them at the connector. Also make sure the pump is turning the correct way. You can reverse wires and the pump will run, just backwards. It's just an electric motor, but in reverse you get no pressure. I'd install a pressure gauge inline so you know what you have. Not sure the Super Sniper will allow a transducer setup via inputs, but you can add a separate gauge to monitor from the cockpit.

Thank you. I did end up swapping the wires at the connector to make the pump turn the right way. I am using an Earl's guage between the regulator and Sniper. The pump provides the 60psi required for the Sniper.