87 renix starting problem

[87woody-atl]

I have an 1987 jeep commanche, aw4 tranny, with 4x4.

As of right now, the problem is this, the starter engages the motor(turns the motor once or twice and then stops,(and it doesn't sound good). Seems to me that signal to tell the starter to turn is stopping when you have the key turned in the start position.

What I have replaces:
new 4gauge wires that run off the positive side of the battery

new 4gauge wire that runs of the negative battery term to the dip stick(ground)

New marine battery terminals

new starter(I'm having the same symptoms with the old starter and with the new starter)

three different batterys( same results with all batterys)

now how the jeep was acting before she stop running:

I was having my voltage drop to 12v when I was running the Ac on full blast
I would gain voltage with the slower fan speed from the Ac.

Then on the day that I noticed my voltage drop, the jeep would randomly die on me,Ex: I left work and it died 5 minutes later, it canker up after a minute wait, and got me home. I drove it a couple more times with the same syptoms, Ac voltage drop and the random dieing while driving.

Well I was goin out of town and need the jeep to get me to the airport and the starter would turn the motor over but as soon as the engine started it would die, so no go to airport.

After trip I tried to start her up, and now it has this problem where the starter turns the motor over once or twice and has a hard stop even though I'm turning the key to the start position.

Where should I look?

 

[joe_peters]

Any of those three batteries had a full charge and a load test applied?

You could have a problem with the starter relay--try jumping power to the SOL wire bypassing the relay and see if she cranks better.

 

[87woody-atl]

The battery I'm using now is a couple months old, I took it of my weekend warrior.

I have a spare new relay. Is the starter relay a little black box with a couple male prongs sticking out of the bottom of it? Is it located on a plastic strip with other black box relays?

And I got to say Joe your the man.

 

[joe_peters]

The starter relay is near those other relays, but it is silver-ish and closer to the battery. It has one large lug for a power distribution center, and three male spade connectors--SOL, 12 volts to the starter solenoid; GRND which is either a ground to the fenderwell or it is where the NSS/clutch safety switch interrupts the ground to prevent cranking; and the last is IGN where the 12 volts comes from the ignition switch.

 

[privatejoker]

You may have more than one issue. Since the NSS is a common problem, I would bypass it by jumpering the harness. It's free and it rules out one more possibility.

 

[87woody-atl]

Ok, now I remember which one is the starter relay, now if I want to jump the starter relay, can I jump it by running a wire from the positive battery terminal to the small terminal on the starter?

My nss switch has been recently cleaned and regreased, but if all else fails how can I bypass that one?

 

[joe_peters]

The wire that attaches to the SOL terminal on the starter relay--if you provide that wire with 12 volts from the PDC lug, the solenoid will engage and the starter should crank. If when you do that it cranks funky, then you have a battery/cables/solenoid-starter problem.

To bypass the NSS to allow cranking all you have to do is pull the GRND wire from the starter relay and replace it with a jumper wire to ground on the fenderwell or battery. IF YOU BYPASS THE NSS--don't allow anyone else to drive it, and be damned sure you don't start it in gear and run over anyone.

 

[87woody-atl]

I jumped the starter relay, with the same result as stated previously- starter turns motor over two three times then stops

same results with the nss

so I pull a spark plug to see if it was gettng spark, it had spark but it wasn't the blue spark that I thought it should have, it was white

just a theory, but would the cps be the culprit, I just can't rap my head around why the starter stops turning the motor over after two or three revolutions...

Plz help jeep has been down for to long

 

[joe_peters]

No. You have a flat out cranking problem.

Either your battery, your cables, or your starter/solenoid are bad.

Just one last thing for shiz and grins--pull all of the spark plugs, then jump the SOL wire again just to see what happens.

 

[87woody-atl]

Got to ask, what is cranking it with no plugs in going to show?

Fuel?

 

[joe_peters]

Just wanted to see how it would crank without having to over come compression--wanted to see if it still had the same symptoms.

 

[Shorty]

Just wanted to see how it would crank without having to over come compression--wanted to see if it still had the same symptoms.

X2^ in other words: verify that there are no other internal engine problems that would keep it from turning (cranking) more than twice.

2-3 cranks (of the starter motor) wouldn't even be one revolution of the engine-- is there any chance of a severely warped or cracked flexplate? If it were to jam the starter
drive gear every engine revolution, it could give you the "crank-crank-crank-stop" symptoms.

 

[87woody-atl]

Well after removing all plugs and starting the motor, the motor did turn over and the problem seems to go away. And after replacing them it came back again. The starter cranked about 8 times then would make the same noise as earlier. Retrying, it would crank 2-3 times and stop again. It seems the starter is not enjoying the compression. The starter is new as well as the cables so it seems there is something I am missing.

 

[joe_peters]

I think Shorty has it nailed--something is binding up the starter. I think its time to pull the inspection cover--remove all the spark plugs again--then get under there with a bright light and prybar and rotate the engine 360 degrees slowly while you inspect the flexplate.

Good luck.

 

[87woody-atl]

Well I just unplugged the cps, and the starter turned the motor over and over with out the stopping as I have described, keep in mind that I have all the spark plugs back in the motor.
As soon as I plug the cps back in the starter turns the motor over a couple times and stops( the same symptoms I've been having)

I've removed the inspection cover and it doesn't look like it's binding up on anything, I thought maybe one of the torque convertor bolts might have come loose and caused the binding but everything looks fine

so where should I go from here?

 

[joe_peters]

Any physical damage to the CPS/CKP crank sensor? You are using the correct shouldered mounting bolts?

Other than the flexplate being loose and impacting the crank sensor simply unplugging it should not have the same effect as removing the spark plugs.

I guess I would unbolt the torque converter, unbolt the trans and slide them both back enough to get the flexplate out for examination.

 

[cruiser54]

Is this the same Jeep that had a torque converter/flexplate/trans front pump installaton problem a while back?

 

[87woody-atl]

Yes it is, I had improperly assembled the torque convertor to the tranny, after I did a motor swap, back last winter. I ended up replacing the torque convertor, tran oil pump, and the flexplate, and a couple seals.

Joe: the cps doesn't have any physical damage, and has the orginal bolts in it.
If there was some binding up in the flexplate, it wouldn't spin freely when I unplug the cps.

 

[Shorty]

If there was some binding up in the flexplate, it wouldn't spin freely when I unplug the cps.

without the load of a "live" cylinder, a cracked flexplate may not twist as much as when the combustion is pushing the crank with some force-- just a thought.

I forget-- did you triple check that the plug wires are following the firing order and you're not firing a plug when the piston is trying to come "up?"

 

[old_man]

Take your jumper cables and jump the negative of the battery to the engine block. Then take the positive side and route it directly to the starter. Give it a crank and see what happens.

I have seen cables corrode so bad inside the insulation, where you can't see, that they wouldn't deliver the current required to crank the starter.