Big Block Billy

A local marina and friend is stumped with a problem in a 350 EFI motor. He changed Ecu's and messed around with the ign. and is not getting the impulse for the injectors.
In my understanding the impulse comes from the ignition, and the injectors ground out to fire, and I told him he has to trace out the wiring harness and it is most likely at fault.
The motor has overheated in the past as well.
Any input would be greatly appreciated... BBB

Dave_N

Did it have the problem before he changed the ECM and what did he do to the ignition? Delco EST distributor? Is the engine getting spark?

Dave

Big Block Billy

Motor has T-bolt ign, and had the problem before swapping with a known to be good ECU from the other good running engine. Any help will be greatly appreciated.
Thanks again , BBB

lowfunds

there are 2 thin wires at the back of the harness make sure they are clean and hooked to ground. these are for the ecm. next thing to look at will be the distributor if it has a delco distributor. the injectors will not fire until the ecm see's more than 450 rpm.

mercmatt24

the module in the distributer tells it when to fire the injectors there is a white/green wire and a white/red wire coming from the distributor if you ground one of those wire with the key on you should get sparkand a injector pulse i cant remember witch one to ground though i always look it up in the manual

Big Block Billy

Dropped off service manual #9 at dealer. It covers full diagnostics and has wiring diagrams. I had problems in the past with cars and had a bad throttle position sensor and that was the fix. Throttle position sensor was swapped with no advantage.
Thanks for the heads up about where to check.
The harness and all sensors are going to have to be traced.
Motor had overheated in past, but had ran fine since.
I have seen all injectors go bad from overheating in the past.
If they can't get it running, I will have to go over there and do the diagnostics myself. I'll keep all posted when resolved. BBB