jimbolo619

Breaking my head here, I have a 78z and found that 3 of the injector plugs have positive current on the two contacts when the ECU is plugged. When I unplug the ECU they go in normal state with one with current and one negative.Im thinking is a short circuit break in the ECU? any suggestions?? Thanks.

theramz

All the injectors should have +12 volts to one terminal with the key on. The ecu grounds three of them every othe rotation ( batch fire) then the other three next rotation. Each injector has it's own terminal on the ecu. You can test the injectors one by one with a 9 volt battery. You will hear it click. If all okay then test the harness, ecu pin to injector plug. You need the FSM for this. Another way is to use a noid light.

jimbolo619

Yeah that's what I thought. There should only be one terminal with 12 volts but three of the injectors with the key on have both terminals with 12 volts which means the computer isn't grounding them. Am i right? I will check the ECU using the FSM thanks for your help Theramz. By the way is that your new Z on your avatar? It looks SWAAAMIN!

theramz

No, it means that those 3 injectors are set to squirt together and make the circuit. There are slight differences in the '78 so be sure to get the FSM for that year.
That avatar is a photo shop creation of mine.

jimbolo619

Oh Ok....ill do some research and look for the exact FSM...Thanks for the help! Man that looks too real to be Photoshop nice job man...Illustrator is a bad *** program for Designs too....yu tried it?

jimbolo619

Ok theramz. I did the FSM testing on the computer plug for continuity and current. All came out good EXCEPT #1 and #5 injectors which aren't getting any current according to the computer plug. However when I check the plugs on each of the two injectors both terminals have current???
Is this normal??Any suggestions?

theramz

As I mentioned before, the ecu grounds the injector for the circuit. So you should have current to the injector. You really need a noid light to check each injector while cranking. It doesn't mean that the injector is good only that it is getting power to fire. I had problems with my 77 as well. I read the fsm at least 5 times. Finally I just went through each test and found that the ecu was damaged by the previous owner. He had switched the +and - from the battery to the ecu.

jimbolo619

Wow...Maybe the previous owner did the same with this one? All the battery wires and injector wires are tinkered with besides that the car also had a big leak from the windshield which could have gotten the battery wet. The weird thing is that I got the car running before and it ran without a problem. I left it two days without running it and it hasnt started since.(about 3-4 months ago). I will check the injectors with the noid light next. Thanks yu been alotta help. Ill keep you posted.

jimbolo619

So Noid light test passed ! I bought a high psi fuel pump and the car started perfectly... i wonder why it messed up my other fuel pump though after so many fuel pressure tests???
Thnks for the help man really appreciate it...The fun part begins now!

theramz

That's great. The bonus is you now understand the basics of all fi systems. It is seperate from the rest of the car.

jimbolo619

Heck yeah you're right! Thnks Man!

jimbolo619

Hey man I really need your wisdom here. There's a relay in the kick pad of the passenger side that keeps making a short that turns off the fuel pump and everything else that should be working when the switch is on the ON place. It is above the small fuse box and is a six pin relay. I have a pic of it if it can help you detect it. If you can help me I would really appreciate it. I looked at the FSM and cant find it. Thanks alot man. I will keep searching.

theramz

That's the ignition relay. The cause could be the relay itself with weak coil or burned points. First try unplugging it and clean the contacts with a spray on contact cleaner. Do not use abrasives.
Does it turn off immediately or when something else changes, like after it starts or when you turn on the lights?

jimbolo619

Weird thing is it shocked me wen I was testing it to see if it was out! Is that normal? It wasn't turning on nor off unless i were to hold a bundle of wires upwards, It was weird! I never seen that happen before but for now its connectors are clean and it seems to be functioning right! thanks so much theramz. I will keep you posted!

jimbolo619

So I cleaned the relay and the trouble was the fact that the cables were being pressed against a negative charged plate near the relay all I had to do was move the wiring to the side. However, the afm is still popping when hard acceleration, once it pops (about 2-3 times) ma baby runs like a dream Does the popping mean Im running rich??? I will rebuild one of my AFMs tomorro..Thanks fr the input theramz.

theramz

You're welcome. That popping is not good. It usually means an exhaust valve isn't opening, allowing combustion back through the intake. This is also very destructive to the AFM. try running a can of SEA Foam in it to see if it loosens up. You might want to check you timing too.