Engine cranks forever before starting

I have a 1990 cherokee 4.0 automatic .when i go to start it i always have to hold they key for around 7-10 seconds (a little worse when its cold but not by much ), and if you count out loud thats along time for it to crank.Its never failed to start though. Ive changed the plugs , wires , cap, rotor, pcv lines, air filter and fuel filter had the pump tested for leak down and it didnt change at all. I had the gentleman at the dealership tell me "all" the older jeeps to that. Any ideas on how to get it to start quicker or is this really something that i need to get used too?

Try holding the key to 'run' for a few seconds to let the fuel pump pressurize, then start it; it should crank much faster. My 1990 does the same thing. RENIX engines are notorious for slow starts.

Get used to it - it's a known RENIX issue (1987-1990 w/4.0L I6.) All four that I've got are the same way - although somewhat quicker. But, I've replaced starters recently...

The RENIX control system doesn't "wake up" and send signals to the ignition and fuel injection until A) it recieves a valid SYNC signal from the sensor in the distributor (or it waits a few seconds, and then starts guessing...) or B) it reads 300 rpm at the crankshaft (I don't know where I got this, and it's probably apocrypha, but it makes some small sense based upon experience.)

If it's running consistently each time, then your SYNC sensor is probably still good - I've not heard of one failing. However, your starter may be just getting weaker, and want replacing soon - the extended RENIX crank seems to do a number on them. Also, having solid mains cables seems to help - at least, that's what some of my customers have told me.

Lastly, the RENIX system seems to lose fuel pressure when it sits over time - someone here has tried putting in a check valve to help prevent this (may or may not work - the fuel rail isn't at a "dead head." If the regulator isn't sealing internally, it will bleed pressure as well.) Try turning the key to ON and waiting 3-5 seconds before you turn it to START. You should be able to hear the fuel pump priming while you sit and wait - it's an electric motor noise behind you. If it starts faster after you've let the fuel pump run to prime the system, then it's a residual fuel pressure issue, and you should look into those check valve posts.

Granted, I've not had one take longer than three seconds to start - I tend to monitor things like that, so I can catch problems before they actually BECOME problems. Makes my life a little simpler...

5-90

Yep i always let the key sit in the on position for a few seconds , thats what drops it from 10 seconds to 7, I suppose until i doesent start ill have to live with it. I hate when people look at me like its not going to start lol

Just the nature of the beast.....I do the key on thing too, then start...3-4 seconds...I just live with it.
Funny thing though.....mine has sat (not started) since 1/31...figured I'd start it for a few minutes yesterday, turned key to on, let it pressurize, turned to start...started immediately..........Go figure.

Might want to change the starter. My '89 was always a slow starter but I recently replaced the 17 year-old starter and now it starts up like a regular car...I apologize for the heresy!