I have a 91 Old's 98...Series 1 3800 non-supercharged.......... when the engine is cold it will not start BUT if I put a spark tester on the 1, 3, or 5 tower (Not on the 2,4,6 tower it'll not start that way as well) on the coil it'll start...... THEN when the engine gets to operating temperature the engine will run without the spark tester in place BUT it will not start/run until the engine warms up......... ANYONE dealt with anything like this? I even moved my grounds to see if it was a grounding problem.......still no luck..........
You need to see if its the lack of fuel its getting first. Spray some starter spray into the intake then start it when its cold and see what happens. If it tries to start then its fuel starvation. If it does not start and you have no spark then you need to check the ignition system as to the why.
So that's weird. Sometimes it helps to have some "spitballing" when trying to track down an issue like this.
When you attach that spark tester the only thing that it can be affecting is the ignition.
It certainly wouldn't help a failing fuel pump, or a malfunctioning sensor.
I'm thinking a bad crankshaft position sensor (CPS), a bad ignition module, or perhaps a bad coil.
I can't see how the CPS would be the culprit since there seems to be an "engine warmed up" improving the problem.
At this point I wouldn't necessarily suspect a failing coil since the vehicle doesn't seem to care which one of the odd numbered plug wires you "bridge" with your spark tester to get it to start when cold.
So, doing a preliminary assessment of the coils is easy enough.
When the engine is cold, like it is in your "no start/no run" unless the spark tester is connected,
pull all of the spark plug wires off of the coils. (mark them so you know where they go)
Have someone crank the engine and watch if spark is arcing across each of the individual coils.
It should be arcing between the 1 and 4, the 5 and 2, and the 3 and 6.
If one coil isn't arcing then swap the position on the ignition module with one of the other coils that was arcing.
(you don't have to put the 2 screws which holds each coil back in for this. All of your plug wires are disconnected so it isn't like the vehicle is going to start)
Crank it, and see if that "dead coil" now arcs in that new position on the module.
If it does, and without doing further diagnostics using a scope (which would be the way to really narrow this down), I'd suspect the ignition module.
If that "dead coil" doesn't arc in the new position, I'd replace that coil.
A bad ignition coil plugged into the ignition module can affect the voltages to the other coils.
Does not have individual coils, it is just one coil with 6 towers. It will only start with the spark tester on the odd plug wires..... It has a new CPS, a New ICM, and a New Coil.