1987 Jeep Cherokee xj slow start...

When I say slow start I mean it turns over 4-5 times before starting. Is there anything I can do to make it start with the bump of the key? It does have 208,000 on it with no smoke or oil burn. It don't even have the little tick my larado had. It was a one owner when I bought it a couple weeks ago. I am taking it in to have all fluids changed in diff. and tranfer case and manual trans. Want to do that before I get on the 4x4 to hard. People that had it really took care of it. no dents good paint smooth engine. Guess I got lucky. 1300.00 is what I paid for it. Think it has Dana 35c rearend under it.

First off, the sound it makes when you crank, namely....rrrr.....rrrrr.....rrrrr etc. Each of the rrrr sounds is a single cylinder going through a compression cycle. Three of the rrrr sounds equals one revolution of the crank.

It takes about one revolution for the computer to sense the position of the crank and start to fire the spark plugs. If it takes longer than that to fire it is normally a fuel pressure problem. There is a one way valve in the pump that works to keep fuel pressure when the engine is off.

Try turning the key on, waiting 5 seconds, turn the key off and repeat a couple of times before actually cranking. If it starts faster when you crank, the problem is the one way valve. One can be installed in the fuel line.

Thanks a bunch. it is just rrrr running. Maybe it is not a problem. Just used to my silverado cranking with the bump of the key.

Yeah, Renix isn't going to fire until the engine is cranking at 300+ RPMs; until that happens the crank sensor won't generate enough of a signal for the ECU to fire the spark.

More powerful battery and a better starter will reduce the start time--how much money you got?

A Mean Green gear-reduction starter would run you around $299.00, then add shipping.

A good, fresh battery and starter, plus 2 or 1/0 cables would get you some improvement in cranking times.

Money is not a problem. I want to make this baby the best it can be. Gonna be my hunting buggy. also my 4 hi light doesn't go off, but all 4x4 works properly. 4hi light just stays on. Vacum?

Dirtnapp said:

Money is not a problem. I want to make this baby the best it can be. Gonna be my hunting buggy. also my 4 hi light doesn't go off, but all 4x4 works properly. 4hi light just stays on. Vacum?

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More likely it is a bad switch, but which switch?

Do you have the NP231 part-time transfer case? Do you still have the D30 CAD vacuum axle?

Dunno. How can I tell?

Ok, is your t-case shift bezel have 2wd/4hi/N/4lo--that is the part-time only NP231.

If you have another selection you would have full-time and that would be NP242.

The NP231 equipped XJs left the factory with a vacuum disconnect front axle--passenger's side of the axle has a lump and vacuum motor.

Put a set of 5-90s cables on your old Renix and starting will improve noticeably.

Another thing that helped both of my Renixes reduce crank time til starting was to "index" the distributor. There are writeups on this and it was a problem in 87 and 88 when the Jeeps were new. Worth doing in my opinion..

Refresh all your grounds in the engine compartment. The dipstick tube stud, rear of the head, and firewall. Remove, scrape and clean all mating surfaces til shiny. Then reattach using dielectric grease on the connections.

I have the 231 2wd 4 hi n 4 lo.
What is the renix

Renix is the running system.. Its Pre-Chrysler 87-90 4.0s were "Renix"

The problem you are having is typical.. The XJ's in general have a terrible "Grounding" system.. it is wise to upgrade and add more grounds. bigger ground to the block, bigger ground from the block to the firewall, big ground from battery to the inner fender/firewall etc etc. also replace old Power cables.. and upgrade size at that time..

That right there will be the Main change in Crank times.. my renix Sometimes starts Quicker then my 5.9..

nw-xj-scott said:

Renix is the running system.. Its Pre-Chrysler 87-90 4.0s were "Renix"

The problem you are having is typical.. The XJ's in general have a terrible "Grounding" system.. it is wise to upgrade and add more grounds. bigger ground to the block, bigger ground from the block to the firewall, big ground from battery to the inner fender/firewall etc etc. also replace old Power cables.. and upgrade size at that time..

That right there will be the Main change in Crank times.. my renix Sometimes starts Quicker then my 5.9..

Click to expand...

Excellent advice. BTW, thank you for Standing With Arizona. We appreciate it.

Your 4x4 light is operated as follows--there is a vacuum switch with three ports located on the transfer case--supply, engage, disengage. Engage and disengage run to the vacuum motor on the axle. There are three ports on the vacuum motor--front to rear they would be disengage, engage, and 4x4 light. From the vacuum motor the 4x4 light vacuum line runs up to the firewall, passenger's side, where it enters a vacuum/electrical switch. When vacuum is applied to the vac/elec switch is completes the circuit for the 4x4 indicator light. Kind of Rube Goldberg in concept but it works.

Rube Goldberg: http://www.google.com/imgres?imgurl...eypCw&esq=1&page=1&ndsp=15&ved=1t:429,r:0,s:0

Thanks guys! I can see I joined a site with lots of correct knowledge.
Just wondering: My AC blows cool when it is extremely hot out, but coming home from the deer camp yesterday it had rain and was overcast and the AC about froze me out. I have a fan shroud ordered but dont have one on at present, could this be part of the cooling problem when outside temps are high? Does having the fan shroud help AC to cool better?

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...)

Thanks for all the info. Anyone on the fan shroud/ac issue?

Not having a shroud reduces the efficiency of the cooling system, the air being pulled through condenser is less effective and that will reduce the a/c systems performance.

damn good info here guys. Ive got the same issue, but I figured it was more caused by a tired starter and engine. It sat for 5ish years before I bought it. Runs pretty good tho but I'll bet after i look into these it'll run a hell of a lot better!

Btw Scott I may have go steal your avatar unless I can find an "I <3 AZ" of my own! Need to pick up some window stickers to slap on the back of my truck, car & jeep right beside the NRA stickers Nice way of telling the local liberals they're #1

cruiser54 said:

Put a set of 5-90s cables on your old Renix and starting will improve noticeably.

Another thing that helped both of my Renixes reduce crank time til starting was to "index" the distributor. There are writeups on this and it was a problem in 87 and 88 when the Jeeps were new. Worth doing in my opinion..

Refresh all your grounds in the engine compartment. The dipstick tube stud, rear of the head, and firewall. Remove, scrape and clean all mating surfaces til shiny. Then reattach using dielectric grease on the connections.

Click to expand...

I'm having a similar problem with my 89. Sorry if this is a dumb question but where does one obtain the 5-90 cables?