Ok, so I have finally determined that my rear primary injector isn't firing. I tied the injectors to the rail and rotated the CAS. When I did this, only the front primary pulsed. I switched the connectors, and again only the one connected to the front primary injector clip pulsed.
So I know that the problem is that the injector is not getting the proper signal. I tested the voltage that the clip sees, but I'm not quite sure what it means. On the good clip, one pin is seeing 12V and the other is seeing voltages all over the place. On the bad clip, one pin is seeing 5 volts while the other is seeing ground.
So what the hell does that mean?

 

maybe rewire them w' nrew clips as they can get real brittle and brake resulting in loss of signal. the clips are real cheap and easy to wire in. can't hurt.

 

I actually already did that while the motor was out because 3 of my 4 clips shattered when I took them off. I wired the new ones in and one obviously works, while the other doesn't. There is some sort of wiring/electrical problem, and I'm trying to figure out where it is. Anyone have any ideas? I'm sure Hailers does, since his posts are where I found out all the test info I know so far.

 

One wire in each clip sees batt voltage any time the key is to ON or better.

The injector pulses by a ground signal being put on the other wire on the injector.

The BAD clip with five volts needs to be looked at. If this car has the solenoid resistor package, then that's where I'd look first.

On that package. There are five wires. One is black/yellow and feeds the other wires THRU the resistors.

Tell you what. I won't go any further since I don't know if your car has the solenoid resistor package or not. Obviously if it does, then the power going into it is plenty good since you see 12vdc on the other plug. It must be either the injector clip or the wire b/t the injector clip and the solenoid resistor package.

So? DO you have the solenoid resistor package or not? And, are the clips mated to the harness good???? Maybe a bad solder joint or bad crimp?? At where the injector clip mates with the harness. This only applys if you have aftermarket injector clips on there.

 

The power supplies to the injectors (the B/Y wire on each plug) are wired in parallel, so if you get two different readings on two plugs something is very odd. Exactly how are you getting these readings? The other pin on each injector plug is a switched ground from the ECU, so you shouldn't see any voltage.

The power for the injectors come from the Main Relay beside the trailing coils. Unplug the 4-pin plug at the relay and check the resistance of the B/Y wire from the relay to each injector. Should be very low.

 

To Hailers: I have an early 87, so yes I do have the resistor pack. I do have new clips that I put in (see above post for reason). As for the joints, I am 100% certain they are good. I don't believe in crimps and I have a Class 3 soldering and circuit board repair certification. If the joint doesn't look near perfect I cut it out and start over. My harness it pretty ratty, so I'm pretty sure there is a bad wire somewhere. Would running a new wire from the resistor pack to the injector clip solve the problem?

To NZconvertable: I got the readings by putting one probe in the pin (when disconnected) and the other probe on battery ground.

Its dark out now so its gonna be dificult testing anything else, but I'm gonna give it a try. I REALLY want this car running tomorrow. My father-in-law is coming down tomorrow afternoon and a friend from out of town is coming down next weekend. Both of them are big-time muscle car guys and give me no end of grief about my car not running. All help is GREATLY appreciated.

 

Well. I don't have a solenoid resistor pack in front of me. How about this. Get your meter out. Put the negative on batt gnd. Then maybe find a sewing needle and probe each of the four wires coming out of the package, looking for batt voltage on each???? Like ***** each wire with the needle and have the meter lead toucning the needle?

OR, being careful, pull the plug off the solenoid resistor. Set it aside. Then find which wire in the harness side of the plug is hot with the 12vdc. the jumper from that pin in the plug to each of the others one at a time til you see the voltage on the bad plug. See if it's now 12vdc or still 5vdc.

 

Ok, I'll go try that out.

 

Or pull the solenoid resistor out and put the meter on ohms. Touch one lead to the pin in the middle and then in turn touch each of the four others with the other meter lead. The meter should read about 6ohms at each pin.

The front and rear primarys are the two pins to your left as you look into the mating side of the plug. See the 87 FSM...Fuel section.

 

Ok, this is weird.
I unpluged the plug and probed the pins. 1 plug had a solid 12V. 2 had a solid ground. But 2 had a changing voltage just like on the non-12V pin on the good injector clip. When I held one lead on the ground terminal and the other on the pin it would slowly make its way down to ground. When I put the other end of the probe on the + terminal it would slowly make its way up to 12V. Why the heck does it do that? Do I have a bad ECU or something?

 

Ok, so think I may have found my problem. I decided to test for continuity to find which wire I needed to put 12V on, but none of the pins on the resistor pack plug have continuity to either of the pins on the injector plug. So apparently one of the wires is just plain bad. Its kinda weird that I get 5 volts on it, though. So I guess I need to run a new wire for that pin?

 

I guess so. Rear Primary is Brown/Red

 

Thats odd, because I just tested all of the connectors to see which was which, and it doesn't match up with that diagram.
Edit: that is actually the pinout for the plug that plugs into the resistor pack, so it should be a mirror image of that on the resistor pack. This is based on wire colors and the fact that my front rotor obviously worked just fine since I drove it around on 1 rotor for a little while.

 

Aw shucks. I kinda remember from the past that, that picture out of the FSM is kinda ....wrong.

Almost matters not as long as all four go to the injector plugs. I'm trying to say one wire to one injector and it matters not which injector as far as THOSE wires are concerned. I mean, each of those wires is 12vdc

The only REAL thing that matters is that the OTHER wire on the injectors is the right color. SEe the FSM for those colors. The wire that runs to the small plug on the ECU that puts a gnd on an injector. Gotta have those right.

 

Yeah, that makes sense. And just to make sure, it doesn't matter which one of the wires it plugs into on the injector as along as both of them are connected, right?
Ok, that didn't sound quite like I meant it to.
They aren't polarized. There, does that make more sense?

Also, I managed to break off one of the wires on the rear secondary right at the clip, so the car won't be running tomorrow anyway. I orded the set of 8 MSD injector clips from Summit. They should get here wednesday so hopefully I can get it all installed wednesday or thursday. I guess this will force me to take my time and do it right....

Anyway, thanks for the help both of you, it was exactly what I needed.

 

Got a little story for you that might/might not apply to what your doing or might do in the future.

A couple of years ago I bought a TurboII intake and manifolds with fuel injectors. All four. Yipee. Surprised me the injectors came with it. So a lately I put two of these HIGH resistance injectors in one of my cars. I put them in the primary spots. They measure 13.8 ohms each. I left the solenoid resistor in line with them to see how stuff works like that.

On the whole it worked fairly well. Til last week. I had removed the 02 sensors plug and went for a ride. Well what is most noticeable is that at steady hwy speed, the AFR read in the 14.7 and plus range and if on a slight downhill it would go into the high 16's. I got out and made sure the 02 plug was sitll off. It was.

I put the 02 plug back on and drove at hwy speeds and the afr stayed in the upper 14range and never strayed into the 16's.

Now what was happening earlier, when it went into the 16's is that it gets lean and *hesitates*, especially when you put the pedal back down to accelerate. But even hesitates when at a steady speed because of the leaness.

Now I compared this car to another car and that car with the 02 sensor disconnected will run in the very low 14's and upper 13's when cruising on the hwy.

So. Lesson learned. I pulled the solenoid resistor out and cut the two wires for the primary's that go to the 6ohm resistors, and spliced it direct to the power wire for the solenoid resistor and reinstalled it.

I drove it and things got better. With the 02 plug off and at hwy speed the afr never slid into the 16's and always stayed in the mid 14's. Put the 02 sensor back on and it went into the 14.8 range because the ECU was controllng the mixture thru 02 feedback.

In the original configuration with high resistance injectors in the primary and the solenoid resistor inline, I didn't notice much of a problem because the 02 feedback was keeping things reasonable.

Even after bypassing the solenoid resistor things are not quite right. I measured the resistance from the solenoid resistor to the small ECU plug. I used a sewing needle and punctured the wire that feeds the injectors at the solenoid resistor. On the stock injectors in the secondays I get 8.8 ohms and at the primarys I get 14.7 ohms. Remember, I bypassed the stock resistors for the primarys.

I still think this arrangement sucks and might just put low resistance injectors back in. They measure about 2.3 ohms and the high read 13.8, by themselves out of the car.

The 8,8 compared to the 14.7 figure ain't a pretty sight. It seems the higer figure makes the injectors run leaner, at least at low or steady speeds. At full trot the afr's were all good and fuel should have been removed. Seems just a steady speed, low pulse trait/problem. Acutally just a problem when the boost was in vacuum, not when in boost. The higher the vacuum,. the greater the *problem*, i.e. being lean.