cabech984

iTrader: (11)

I recently completed my swap of a Gen-III 6.0L V8 into my 1990 Firebird with a TH400 transmission. I have a custom Speartech wiring harness that was made for the thirdgen fbody swap with a 4L60E. I also have a Fuel Pump Hotwire kit installed too. The engine is untuned but shouldnt make a difference with the engine off.

Anyways, with the KEY ON, ENGINE OFF, I can hear the fuel pump prime while in park and in neutral. But, as soon as I put it into a drive gear, the fuel pump stumbles and dies.

What could cause this issue? Bad ground, bad voltage signal to something? Or could some of the 4L60E controls be causing this? I have the 4L60E wiring in the harness, but a TH400 transmission.

I need help before I send it out to the Dyno Tune shop!! I want to make sure all my electricial quirks are solved before I get it loaded on the trailer!! Chris

69LT1Bird

iTrader: (1)

Key ON engine OFF, the pump will go through a prime cycle for two seconds and then turn off. It should not continuously run if the engine is not running.

If the engine runs, what is the concern?

cabech984

iTrader: (11)

Well, the engine runs in park and neutral, when I put it in gear it dies and the fuel pump no longer runs. The fuel pump loses 12v or ground when put into gear, engine running or not(doesn't matter). I just thought I'd try to get some ideas of what to check(p/n switch, hotwire kit, trans diag via hp tuners, etc) before I dig in on my own when I get home!

cabech984

iTrader: (11)

I believe I got it figured out. I dont have a fuel pump relay wired in, Im a genius for not installing one haha. It was wired straight from the PCM to ignition voltage