2003 Mach 1 - F1.28 Fuse blows on KOEO

[fr500mach]

Hi,
So seeing if anyone has pointers on where to look.

Car is a 2003 Mach1, heavily modded. Stroker car and engine was recently pulled and refreshed.

Car will not start. Key on Engine off F1.28 (30AMP) blows immediately.

Things to consider:
1. Battery is in back of car.
2. Recently this happened and we swapped out the CCRM with a friends and replaced the 30A fuse and it ran fine (for a short time)
3. The fuse seems originally to blow when we gave it any gas.

Things I have done.
1. Checked grounds. Engine to Body via motor mount, Engine to Battery via motor mount. G03 & G04, under dash grounds.
2. Checked other fuses -- none blown.
3. Tried to run a scan, but will not run, appears car is in PATS.
4. Dash has flashing alarm and --------- across the odometer.

Any ideas on where to go next?

 

[Noobz347]

Unplug MAF, injectors, EGR/EVR, cam/crank sensors — try key-on.

If fuse doesn’t blow, plug things in one at a time until it pops.

If fuse still blows with all sensors unplugged, check for pinched injector harness or 12V short near firewall/trans.

If needed, isolate the PCM entirely and check continuity from F1.28 to PCM pin 55 and other powered components — see what’s dead-shorting.


Theory:
F1.28 feeds into pin 55 (PCM power) and a few CCRM circuits. If it’s blowing immediately, there's likely a short to ground in one of these:

Injector power supply (Red wires, common)
MAF power wire
EVR solenoid
Cam or crank sensor power supply (5V ref circuit)

 

[fr500mach]

Well it came back alive. I regrounded all major grounds, unplugged all sensors, blew them out, repluged and its back alive

 

[fr500mach]

So oddly enough, 1st gear pulls hard, no issues, everytime we get to 3rd gear hard pull the fuse pops again. We have narrowed it down to unplugging injectors 5-8 and the fuel injector sensor