robertf

Anyone know the minimum voltage required to fire a tbi engine?

I've got an engine with a tbi conversion on it that will not fire the injectors or coil (or noid light and spark tester) while cranking. shows between 9.75 and 10.5 volts while cranking and 12.5 when switched to the on position.

it fires the injectors and coil if I wave something by the pickup in the distributor, and runs just fine if I start it with starting fluid (must be dieseling the ether since its no spark) only thing I can think of is voltage requirements not being met. Is this a problem anyone has ran into before?

RBob

iTrader: (1)

The 9.75 and 10.5 volts should be OK. My Firebird drops to 8 - 8.5 volts during crank and it starts up (battery in the trunk). Check that there is still power to the coil and ECM while the ignition switch is in the crank position. Sounds like the ether starts burning and you let off the cranking, which has the run position supplying power and the engine keeps running.

RBob.

robertf

there is power to the ecm, coil and injectors while cranking. I'm even able to log the voltage drop while cranking through the aldl port. all 3 of those things are as close to the battery as possible too (40 amp relay)