Minimum requirements for testing TBI system on engine

[kilohertz]

Hi guys,

Getting ready to test fire the '91 1227747 TBI system on my '49 Ford flathead and am wondering what are the absolute minimum requirements for sensors and connections to get it to fire just in open loop mode? Besides the obvious fuel pump and distributor.

From what I have researched, I think I'll need the coolant sensor connected but doesn't have to be in the water stream, TPS, IAC, MAP, don't need an oil pressure switch, just the fuel pump relay, no ESC or knock sensor, read somewhere that the ECM pin needs to be tied to 5V reference for this?? Can someone please confirm if this is true and what pin it gets tied to? Probably don't need the O2 right away either...

I think that's it, let me know if I am on the right track please and thanks.

Cheers

PS one other Q, could someone please tell me what the ALDL signal voltage is out of the ECM, is it pulsed 5V or 12V? I'm building my own cable and thought I might be able to use a cool little RS-232 to 485 adapter I have. thx

[1project2many]

ALDL volatge is usually listed as TTL switching... 5V, yes?
This has a bunch of helpful info and links:
http://67-72chevytrucks.com/vboard/s...d.php?t=698079


How well do you want this system to "fire?" You can get it to generate an injector pulse and a spark with only fuel pressure and a distributor pulse. Run? Maybe??? Otherwise you only need three sensors: TPS, CTS, and MAP. The oil pressure switch is wired in parallel to the fuel pump relay. This helps prevent the relay from arcing when driving over rough roads. 7747 does not use an intake air temp sensor. But you will find that the engine does not want to idle properly, once you start driving, if you do not use a vehicle speed sensor. This will be epecially true if you are using a manual transmission.

[kilohertz]

Thank you, that's exactly what I needed to know.

The truck is far from drive able, I am just in the process of proving it will work on the flathead before I start making up permanent harness and building brackets and such for coil, MAP etc. Finally received all the required fuel connectors yesterday and I am going to be assembling everything this weekend, I'm just going to hang the ecm and harness loosely on the cowl for now. Also need to finish the distributor machining to fit the flathead, should have that done today. I have attached a couple of pictures of the adapter plate I made.

Thanks again!