cderwin

I did the 305tbi to 350tbi swap in my 91 firebird. I have done everything your supposed to do and my car still won`t start.Im getting no power to the fuel pump and my injectors won`t spray fuel.I changed the ecm , esc , fuel pump , knock sensor , injectors , all fuses are good and there is power to the injectors.Also changed the oil pressure switch and it will start if i spray fuel in the tbi. Can someone please help cause i have read everything here and i can`t figure it out....Thanks

golden

Check the fuel pump wiring diagram , and see if theres an open circuit ....

Irocwannabe

iTrader: (5)

dont know if this help but i had the same problem with this formula i was working on a while back and i swear we changed everything fuel,fuse,and electrical related other than the harness and we were still gettin no fuel but when ever we put a 12v connection to the fuel pump wires it would kick on no problem so we figured it was a short which sucks to find, anyway some one told me the was another fuse to the fuel pump under the hood just behind the the driverside head light and that was it, changed that little fuse and turned the key and everything turned on fine . need less to say i was pissed about all the time i wasted but almost everything electrical under the hood is new

cderwin

Thanks for the replies but i have checked the fuse by the batt and its good. If i run 12v to the fuel pump it kicks on and fuel gets to the tbi.I have replaced and checked just about everything on the car with no luck. I don`t understand why im having this problem if everything was working fine up to the engine swap. I even drove the car on the day i swapped motors.Im thinking i should have just stuck a 305 back in. Im so fustrated either im thinking either swapping to carb or pull out a for sale sign.Don`t really want to do either.

The computer i have is 16136965. I checked the part # and its a caprice 91-93....thats the computer i need right?

RBob

iTrader: (1)

That is not entirely the correct ECM, however it should work.

When you jumper +12v to run the fuel pump, does the engine start and run?

If so then the fuel pump relay driver is the ECM may be toast.

If it doesn't run then I would suspect that the DRP is either not getting to the ECM, or the ECM isn't seeing it.

RBob.

cderwin

When i put 12v to the pump it won`t start cause the injectors are not spraying but they have power to them.It will start by pouring gas in the tbi.What do you mean by its not intirely the correct ecm? I may sound stupid but what is the drp?I am new to the tbi and im not good at trouble shooting electrical problems. I have learned alot and willing to learn more....

RBob

iTrader: (1)

One difference between the '8746 & '6965 ECM is the AIR control. The 8746 uses pin C2 for one of the soleniods, where the '6965 uses pin C2 for A/C compressor control. There may be some others, but 98% of the wiring is the same between them. I would unplug the two AIR connectors under the hood.

A DRP is a distributor reference pulse. The ECM needs to have these in order to fire the injectors. At each DRP the ECM will fire one of the injectors, and alternate between them.

If you have the stock '8746 ECM try it and see if the engine starts. If not then the distributor or distributor wiring may be incorrect/bad.

RBob.

cderwin

Good news guys my firebird is running.After 2 months of pulling my hair out my ecm was getting no power.Something simple and as stupid as that.I ran a jumper wire to where the fuse is by the battery and my car started right up.Whats wierd is the fuse thats in there is good but the ecm still wasnt getting power.This is starting out to be a good weekend. Thanks to everybody that tried to help me out.

fbird92

I know you said you checked the oil pressure switch but did you check the wiring for it? A wire shorted out and broke to my oil pressure switch and cut power to the pcm and had no fuel pressure or injector pulse. But the fuse under the hood that controls the fuel pump and oil pressure had blown so it was easier for me to find. I would just double check the wiring. cause it sounds you have the same symptoms as me but i had a blown fuse and i didnt

cderwin

Now that i have the 350 in my car the air cleaner is to tall for my hood to close. I used the mounts from my 305 but it sticks to far up.Has anyone had this problem when they did the swap?

Pontiackid

iTrader: (3)

i just figued out i have the same problem, ive been trying to figure this out since christmas. i did the jumper from the fuse to the positive and it works. but the first tim ei checked the fuse 2 months ago it was blown, i replaced it with a good fuse and it still doesnt work. is it a short in the main power wire? thanks and can i just run a new one?

ewalker85

I'm putting a 5.7 tbi into a 87 Monte Carlo that had the 4.3tbi in it. I am running into this very problem and seeing if anyone has any other input. Tried the wire jumper but no luck. Getting a fresh start in the morning but any help apperciated