bakomack

1988 mustang
Car has a 5.3/4l)0e swap

Summary: car made 665 on 10psi using a modified stock harness
(Green/blue) ecu so drive by wire.

I parked car for a trans leak (o ring on trans tore) last December in running condition.

I added the following parts:
Ls9 cam/ls3 springs
Fast intake with fuel rails
Accufab throttle body
And a new custom standalone harness (red/blue ecu)

Ecu has been flashed and car will fire up but only in crank position, move the key back to run position and engine dies.

I installed two distribution blocks, one 12 batt and one is key power. To feed engine harness and gauges.

Everything works fine until key is switched to run position. Any idea what is going on here

EFIHARNESS

Check that you have power in the start and run position. some switches cut out one circuit
when you turn to the start position. Steve

lsxRanger94

Also check fuel pressure and make sure fuel pump does both prime and run when engine starts.

bakomack

Have fuel pressure and spark. Motor will start and idle with starter dragging. Upon releasing the key dies instantly.

I have a relay wired to a distribution block for my key power. ( harness and aftermarket gauges all wired to this distribution block)
When I move the key to run position the relay kicks on. When moved to crank position the relay clicks off and upon the key moving back to run the relay kicks back on.

Took my power probe to the trigger wire of the relay to force it on while I started the engine and cycled the key to run but engine still dies. Stumped right now

Jimbo1367

Make sure all header tubes are firing. Hold the starter on for a few seconds, then check to see if the primaries are warm. If you find a down cylinder, check the plug. etc…. Try to push all injector plugs tight. Make sure you have your MAF plugged in and inline with the CAI. RECHECK YOUR GROUNDS. <-- Use a test light to make sure. Make sure your battery is fully charged.

lsxRanger94

Are you sure VATS has been removed?