Senorhowarth

Hello forum members

I have removed an ls1 from a donor car and now is on an engine run stand. Engine was running fine prior to removal but now I am having some issues.

Engine fires for one second but won’t run and seems to be flooding itself.

PCM has a mafless tune and Vats has been disabled.

I am using the fuel pump from the donor car and am getting 60 psi at the rail. As soon as I disconnect power to the fuel pump and crank the engine it will fire and run on the fuel that is left in the rail.

Not throwing any codes and everything else seems normal in the OBD2 live data.

Can’t work out what I am doing wrong as it was running sweet before removal.

Any ideas?

strutaeng

Double check VATS is deleted. I tried to start the 5.3 swap on my truck with the stock computer.

I was shocked it actually fired up, but died immediately. When checking fuel pressure with a guage and injector pulse with a LED test light, both immediately stopped or died upon startup. I think VATS cuts both fuel pump power and injector pulse when enabled.

After I took the ECU to get the VATS deleted all was well.

Senorhowarth

I have tried to start engine again and have discovered that it will run with the throttle blade cracked open. I have used a scan tool to check and tps is 0% when engine is shut off. is there a way to check or test that the IAC is working correctly? I’m really not sure why it seems to be dumping fuel.