Dwax13

Ok I have a few questions about the ecu as i am converting over to carb i have a 1986 trans am with the 305 tpi when i got to taking the ecu out there is a like a small yellow box attached to it can i just unplug everything that goes to the ecu and to the small yellow box. Im wondering this because i still want my guages to work. Another thing is the tpi wiring harness does that only go to the computer or where else does it run throughout the engine bay. Also all the relays on the drivers side engine bay will i be able to just remove them? i know the fue pump is controlled through there but i plan on running it by a toggle. Any imput on this would be great!

camaronewbie

Guages should still all work. Just unplug the ECM - remove it, leave it, whatever.

Don't jury rig the fuel pump on a toggle - make use of the wiring you have, and utilize the relay you have - replace the green/white wire going to the relay with a hot-in-run connection - that way fuel pump will run with key on, won't run with key off. Last thing we need in this world is another 3rd gen with a boat-load of toggles cut into the dash.

TPI dual fans cars - the ECM controlled the primary fan, the pass side head fan switch controlled the secondary fan - no ECM means no primary fan - you have to rig the primary fan in with the secondary so that it operates off the stock fan switch (and replace the seitch with a lower temp switch), or get a seperate fan controller - I use the Flex-a-lite controller, it's very easy to wire, probes radiator for temp input, fully adjustable - a real nice piece - costs $100, but it's the best $100 I ever spent!

If you are automatic tranny, make sure you get the geometry corrector for the carb you choose, and you'll have to do something to lock the torque converter.

And of course, if using the stock intank fuel pump, you'll need a retrun style pressure reg like the Mallory 4309.

And please dont cut/yank/hack the pass side wiring ... 1) you need to leave it in place until you are 100% sure everything works correctly, and 2) you can sell it later if it's intact (along with the ECM) as a TPI package as they are desireable by some.

Apeiron

You can leave it intact and let the oil pressure switch power the pump as well. This can have you cranking a while to get the car started if the bowls are dry though, but wiring the relay coil to a hot-on-start wire would solve that problem.

Dwax13

alright thanks guys i didnt want to hack up the wiring. i wanted to try to remove everything i didnt need in complete form. Do you guys have any other advice for the swap?

Dwax13

oh and what is the yellow box conected to the ecu? and what is it for?

five7kid

iTrader: (14)

That is the vehicle speed sensor (VSS) buffer. I forget off the top of my head if '86 'Birds had cable drive speedometer or transmission-mounted VSS. If cable drive, you don't need it.

Dwax13

Do i unplug all the relays that all the wires run to on the drivers side firewall?

Dwax13

Ok guys its been awhile and im getting ready to put the engine back in the car soon i still need to figure out my fuel situation i dont think i have a fuel pump relay? i know i removed all the wires that came from the ecu along with the ecu when i sold my tpi as a complete setup. here is everything i have left? how do i get my fuel pump to kick on when i start the car if i dont have the relay?

Dwax13

anyone?

travis401

iTrader: (1)

if you removed the fuel pump relay, you can always wire in a new one...

Dwax13

I removed my oil pressure switch also so i cant use it to trigger my pump ive heard its not needed for a carb car since no prime is needed the fuel in the bowls will be plenty to start the car. so how would i wire it then where do the fuel line wires for power run?

Dwax13

bump...i need help here guys

travis401

iTrader: (1)

if you removed the fuel pump relay, you need to wire one in. the fuel pump wire should be on the c100 connector, but im not entirely sure on ur 86. you would need to look at a diagram and find a spot to tap a relay into the fuel pump power wire.

sbcshawn90

Anyone ever find where the fuel pump wire is at on the c100 on a 86