Another factor that can contribute to slow starts with RENIX is the firewall-engine ground strap. This is the only ground for the chassis (adding a direct ground from the battery to the chassis is something that ChryCo actually did correctly,) and the ECU is in the cabin and grounded to the chassis (while the sensors are all grounded to the engine.) This can result in 'floating grounds' - which will cause all sorts of headaches. That ground strap is often called "The RENIX Killer" - and for good reason.
Things to check:
- Make sure the battery is fully charged. More charge = better starter motor cranking.
- Is the starter motor clean? Oil outside (from an engine leak) usually results in oil inside - which will slow the thing down.
- Make sure it's mounted nice and tight as well. It grounds through the mounting screws.
- Inspect the mains cabling - there are two hot leads: one to the starter motor (cranking) and one to the starter motor relay (main power distribution by way of fusible links.) The shorter one can often begin to corrode under the jacket, and this will screw with things.
The advice on fuel system priming is spot-on, but isn't a guaranteed fix. You may have to attack this problem from several directions, which is why I gave you a few other things to check.
RENIX is "pre-OBD" and doesn't "store" or "throw" codes, but nearly all troubleshooting with RENIX can be done with a DMM - and it's easy! Copies of the RENIX FI manual are available online (I got mine at Pirates of the Rubicon, and host a copy at RENIXPower. If you sign up there, make sure you tell me who you are and why you want to be there - I've had to shift to full moderation to cut the SPAM down...) and you can download a copy gratis.
I do prefer the RENIX setup over OBD-I, and I find OBD-II a close second. This is probably because I came up on points and condensers, and I'm just too used to doing my own thinking when troubleshooting (and I've known OBD-I and OBD-II to be wrong on enough occasions that I have a hard time trusting them. OBD-II is at least standardised by SAE, which means the system makes more sense than OBD-I...)