I'm having trouble getting the engine to start. Sometimes it will start and sometimes it will just crank til I kill the battery. Usually will start if the engine is cold, and will run fine. But once its warmed up and I shut it off it does not start very well or at all. I can smell fuel (not a strong smell) and I hear the fuel rail charge. So I think its a weak spark. I have had the battery tested and its good, and I swapped the ignition coil. I have a MSD 6AL box and I did the white wire test, which tested good. If I hook up my timing light to #1 plug wire and crank it over and I watch the flashes. It will flash maybe once and then a long pause as I continue to crank I then might get several multiple flashes and then a long pause of nothing til the battery gives up. I'm also using a battery charger and setting to crank start to give it a kick. I also have a MSD distributer, cap and rotor.

Stick that timing light pick-up on the "spark plug like wire" going from the coil to the distributor. Then see if you get the same intermittent sparking.

If yes and you have a new coil, then check the electronics prior to the coil.

Also the signal to spark would come from the engine computer. Automotive computers might not work if the battery voltage is below 9 volts when cranking. So keep the battery fully charged (with battery charger) while troubleshooting this problem.

I think I may have figured it out. I pulled the cap and rotor off. There was alot of build up on all 8 inside contacts, so I scrapped the build up off. I also bent the tang on the rotor up a little so it has good contact. I then put it back together and pulled the fuel pump fuse cause I just wanted to see if I would get spark using my timing light. Well As started to crank the engine it started right up. Its never done that before. I usually have to crank it over a few seconds before it will fire. So I shut it off, put the fuse back in and started it right up again. Since I pulled the battery earlier to have it tested I was letting it idle a few minutes so the ecm could re-learn before I took it for a spin. While it was idling the engine also sounded alot crisper. Which I'm assuming I'm now getting good air/fuel spark mixture.
Still got more testing to do though!

Well its still being stuborn, won't start. So my next thought is maybe the ignition module is going south.

If you are not getting spark out of the coil (and the coil is good), then I would suspect the ignition module.

Well I replaced the ignition module and still trouble starting. Is it possible that since I don't have a heat shield on the starter that the starter solinoid is getting heat soak and is struggling to crank over the engine from the heat my headers are putting out?

Huh????

What *exactly* is/are the problems here?

I thought the problem was with no spark?

Now are you saying you turn the key to start and the starter does not crank the engine?

If the battery is low, charge it...

I'm chasing ghosts at this point, cause I can't figure out what is causing this problem, so I'm expanding outward on any ideas!
To start over; when the engine is cold it starts ok, not the greatest but I usually can get it to start. Once it warms up and I shut it off and try to re-start it, this is were I start to run into problems. So far I've checked the battery out had it tested and its ok, changed coil, cleaned up the cap and rotor, checked the plug wires, spark plugs are new, replaced the ignition module, and tested my MSD box.
I thought maybe if the starter solinoid is heat soaked it would be struggling to turn the engine over and I would be reading it as weak spark when using the timing light to check for spark. I actually thought to bring it in and have it checked out. Since I've been doing all this extra cranking I maybe killing the starter/solinoid.
I'm running out of ideas and don't know what else to do!

when the car is hot, and you try to start it, can you hear the starter turning the engine over? is it sluggish, or not? If not, thats not the issue

The best way to analyze your spark is through an oscilloscope. You can view all stages of the spark, there are either four or five I believe. And you can determine whether each cylinder is firing correctly, it is not very practical because it's probably difficult to gain access to one unless you work in a shop but it will definitely tell you how well your plugs are firing.

Yea,
I can hear the starter when I'm cranking. When its cold it turns over ok. But Once the engine warms up and I try to restart it.The starter sounds sluggish til it won't crank no more. But I thought from the excessive cranking that it was just draining the battery.

I had that happen with my old starter motor. When cold, car would crank over nice and strong. Once the car was hot, it sounded like the battery was flat. Give it 10-15 minutes, let it cool down, then it would crank fast enough to start again.

I replaced the starter motor and it cranks over nice and strong plus faster no matter if it is cold or hot. You could even hear how much faster it was cranking over.

Sounds like dejavo!!!
Theres a place near my house that does starter and alternator rebuilds, plus they test them too. So I'm going to get the starter over there this week.