87 TII

Car was running, hit the AC button and a few secs later - poof - engine stopped running. So far I've done a great deal of troubleshooting but haven't found the issue. I have power (11-12v) on 1A ,1B, 3I, and 4J as per the FSM. I checked the ground connects at the ECU - they all seem good. I've switched out the ECU. I checked the resistance by running a long jumper from the solenoid resistor to the the green wires (3C and 3E) and I've got 14ohms. I have 12v on the BY wire on the solenoid resistor. The CAS seems to have the correct resistance. I put the timing light on each of the high tension wires and I see that the light is flashing when I crank it. The fuel pump is running and seems to have the proper pressure(I jumpered it for testing). There just doesn't seem to be fuel delivery via the injectors - easy to tell as there is no gas smell at the tail pipes.

I pulled the fuses under the dash - all seem good. All the fuses check out under the hood as well. I feel like the problem was triggered by turning on the AC, although it could just be coincidence.

I'm at a loss here, any help/tips are greatly appreciated.

 

MAF working correctly? Maf controls fuel pump while cranking and running. Try jumpering fuel pump green connector?

do you have 12v at the engine harness? CAS does run separate harness from engine so you should check engine harness if you haven’t already. Double check your fuses, especially the “engine” fuse under the dash.

 

Yes indeed, the MAF is working - I have an extra for testing - both test good (opening flap kicks on the fuel pump) - Also tried the pump jumper as well just to make sure.

When you ask "do you have 12v at the engine harrness?" which harness?/plug are you referring to?

Where/how can I check the CAS harness from engine?

Which fuse is the engine fuse?

Thanks in advance for you help!

 

I checked the CAS harness to the ECU and I have good continuity on all 4 wires

 

I checked all the fuses under the left kickplate - uncluding the two bulky black ones - they are good.

 

i was going to say, the stock ecu defaults to flooding the car if it has power, and a CAS signal. no CAS no fuel

 

I checked the continuity of both sides of the CAS at the ECU as well. I have 155ohms on both sides which are within spec.

 

does the tach bounce when you crank it?

 

The TACH does indeed bounce. Also I pull L1 spark plug - there is definitely fire when cranking.

 

ok if tach bounces that means the ECU is working. so you either have no fuel at the injectors, or there is some issue with injector power.

if you're lazy, plug in a spare CAS (hopefully lazy and prepared?) and spin it by hand, you should hear clicking. if not, then at the ecu you want to see if there is 12v at the injector wires with the key on (engine off). ecu is the ground side, so if you have no power its like main relay, main fuse, etc.

if that part check out ok, pull a fuel hose off and jump the fuel pump test connector and see if anything comes out.

 

It has to be something with the injector power. This is what I did - I pulled out the CAS (b/c I don't have an extra) - disconnected the power to the coils (I could hear them ticking when spinning the CAS). When I spin the CAS with the key ON I can't hear the injectors ticking at all.

I measured the voltage at the ECU (See photos below) - I'm only seeing 1/2 a volt on each primary which definitely doesn't seem right. Which is the main relay? Is it the one up by the trailing coil pack? If so I've swapped it out with no change it does click when you put the key to ON. By the main fuse do you mean the one under the hood that you have to unbolt to remove - if so I have 12v on each side. Thank you so much for your help btw ... I really do appreciate it.

 

Engine fuse is below the dash on the driver side. 15A. Double check grounds.


You should be able to see 12v at almost any connector on the engine harness. You did use the maf, so I’d assume voltage was okay but I’d test somewhere else just in case, especially with the half volt reading your getting.

 

Yeah all the fuses in the underdash drivers side fuse block have voltage on both sides. Something I just discovered though - If I turn the key to OFF and then back on again and spin the CAS I can hear both injectors fire in rapid succession - but just once and then nada. I can repeat this over and over with the same result. What do you make of that?

It's possible the clicks that I am hearing are coming from a couple of the solenoids on the fuel manifold...not sure, would have to remove the UIM and I really don't want to take off the UIM...

I pulled the small plug off the ECU and tested the wires, on the harness connector side, for the primary injectors, and I'm getting a cycle from 50 to 300 mV (yes millivolts).

 

that should be 12 volts with the key on. it goes battery -> main fuse-> main relay -> one of the fuses in the main fuse block (i forget) -> injectors - ecu - ground.

actually if you have an 86-87 car with low impedance injectors, the resistor thing goes bad sometimes, it would do exactly what we are seeing

 

I replaced the original injectors a few months back with high imp. I have one of the resistor delete blocks.

 

Well what do you know, it was the injector resistor delete (pictured below) that I bought from eBay.
Turns out it wasn't made very well, I stripped off the old shrink tube, found they only crimped the wires with a cheap aluminum ring - and not very well.

So I un-crimpped the ring, re-twisted the wires together, added flux, and soldered the wires together with some good silver solder and replaced the shrinktubing.

Now my injectors click when I spin the CAS!!! YAY!!!

Let this be a lesson for anyone changing injectors from low imp to high and buying a cheap resistor delete from eBay (most likely made in China). Go ahead and replace the crimp with good solder before you get stranded somewhere.

And a shout-out to those who provided support - I really appreciate it!