93 Festiva, injectors won't fire

[dtischer]

Hey I'm new to the forum, but I just recently bought a 93 festiva that didn't currently run. It has spark and cranks over, but the injectors don't fire. I did resistance tests on the injectors and i used a noid light on the harness and found that there was no power getting to the injectors. It has power going to the main relay and power coming out of the main relay but I'm not sure exactly where to test from there. any advice or help would be appreciated. thank you

[dalebwilson]

Check the EGI fusable link mounted on the drivers side shock tower. It supplies power to the fuel system.

[dtischer]

I had done some researching and mine was all cut apart. i would assume from the previous owner trying to get it to run. i put in my own fuse box and rewired that whole thing. so i don't believe its that.

[william]

Check Main relay left inner finder behind headlight.

[dtischer]

I've got power going in and coming out of that.

[dalebwilson]

If you have validated that all harness wiring is correct per the diagram in the Haynes manual and you have no shorts or grounds, I would consider switching out the ECU. Someone on here will have one you can use.

[tooldude]

The noid light is only telling you that a circuit is not being completed from B+ voltage to ground. Check for voltage at the injectors on the Y/BK wires. If you have B+ there, then the computer is not grounding the injectors.

[dtischer]

I tested the y/bk wire on the first wire and with the key on it read 7.5 volts, when i cranked it the voltage dropped to around 5.7. Does this mean i have a bad ecm? Whats the next step or a solution?

[tooldude]

Those voltages are too low. That is below the threshold generally given in textbooks at which the ECA (computer) can operate, although I don't have a specification for Festivas. 5.7V may not be able to open the injectors. If you have the wiring diagram, you will see full positive battery voltage goes through the EGI fuse link, main relay contacts, then to the injectors. Check battery voltage directly on the posts to see if it needs charging and to establish its exact voltage, for which you're looking at every connection. Make sure the battery posts are clean & the negative cable ground connection is clean and there is no corrosion inside the battery cables. You may have to clean ECA grounds in the engine compartment & on the engine. If you have to clean heavy corrosion or charge the battery, measure the voltage drop of the battery during cranking again to make sure it can maintain voltage under heavy current draw (I believe ~8.5V min). Make sure the EGI & all fuse link connections are clean. If you still don't have correct battery voltage at the injectors, the relay contacts may be bad. You can jump the relay contacts (W/BL to Y/BK) or replace the relay and check again.

[dtischer]

i think i have a wiring diagram, but is there any way anyone could upload one for me to look at?

[tooldude]

Enter keywords such as "wiring diagram" in the advanced search box at the top right of this page. I know there are some on the site but I'm not positive it's the page you need. I'm not able to put that on right now. The wiring harnesses are identical 1990 -1993; you can go by any of them. I'm running out of computer time, I may not be able to try to help you until after saturday but there are plenty of others on this site who can help you with this.

[wth]

If you find out that you need a ecu let me know I have 3 of them all are 3 plugs 25.00 ea. shipped

[WmWatt]

There are wiring diagrams in the back of the Haynes manual.

BTW I just found out this week our public library subscribes to the online version of the Chilton manuals. I can view them on the library computers or on my own computer by tying in my library membership number at the library's website.

[dtischer]

on the egi block there are three wires going into one side and one black wire screwed to what looks like a plate going into the other sides. I would assume the black one is just a ground? If i am correct, when i went to test for a ground there was nothing. i tested the w/bl wire and there was 12 volts there but when i went to test the ground on the other side there was 0 volts.

[dalebwilson]

If I am understanding you right....there is no ground on the fusable link (EGI) block.

Here is a snapshot of the wiring diagram on this site. All positive wires.

Fusable Links.jpg

Sounds like you have a weak or broken fusable link.

If I am off base...I apologize in advance.