So this heap has been sitting in my garage for a while, as I haven't had too much time to wrench on it lately.... Since my last post, I've:

Pulled the starter, had it checked at Advance. the starter is good. Put the manifolds and throttle body back together. Still no start.

I then tapped into the physical ignition wire at the key switch, and ran a new one (wire) to a relay that activates the starter when the key is turned to the start position. The car now cranks hard. (hurayy)

My issue now is that I have a crank w/ no start condition, and I have a feeling that I'm also bypassing a system that the car needs in order to start. I pulled a plug on each bank and have verified that neither side has spark during cranking (or ever)..

After checking the plugs for spark, I replaced both coil assemblies as both units were cracked, and the ohm level was out of spec (according to the source I used) still nothing.

I've also put in a new Crank Position Sensor.


Can anyone tell me what I may be bypassing by running a wire directly from the key switch to (basically) the starter? when I crank the vehicle I can smell fuel.

Thanks!

 

Anything from igniters (ignition control modules) to the ecu. Do the injectors get a signal? If you had to run a wire, and since wires just don't go bad unless it a mouse chewing them, you probably have other things happening.

 

What would be the best way to check this?

Today I verified that the coil is getting power (via voltmeter), and is sending the power to the distributor & rotor. It seems that this is where I run into issues. I'm seeing very low to 0 current coming from the distributor cap (to the plug wires) thus not sparking. (on both banks)

I cleaned up each of the contacts on the distributor cap, with no luck. How would I know if I need to replace these? is this a common failure?

What would a healthy coil output be voltage/ current- wise? and what readings should the distributor cap contacts (to the plug wires) be seeing when tested/ measured?

 

Noid lights, also there are special probes that detect injector operation.


Check for spark.

With a High V probe you should see up to 30KV depends on gap too.
It is a very low current system. How do you know there is low current?
Did you plug in the spark plugs and look for spark?

 

It is good that you have that "feeling" because you are probably right. You should fix the root cause there, not bandaid and bypass the original design. Without knowing exactly how you wired the starter in and bypassed the system, it is not possible for this forum to say.

Why don't you go back to square one and get the ignition switch/starter circuit working as the factory designed it to work? It is probably something fairly basic and simple. You will "chase your tail" (throw any time and money) for a long time trying to overcome the bypass.

 

Hey guys,

I recently realized that I never updated this thread.

I ended up selling this LS400 back in early 2015, as I Moved to Pittsburgh and didn't have garage space for the LS. I sold it to a tech at a dealer who ended up fixing the issue relatively simply. He found that there is a 'security box' in the drivers side kick panel that had a broken circuit that he re-soldered back together, apparently the car fired right up shortly after. oh well, you live and learn.

​​​​​​^^ Dicer was on the money in Post #2

I would also like to say thanks to anyone who offered input in troubleshooting this issue!

The good news is this otherwise MINT '90 LS400 was put back on the road and is running great!