Problems Starting

[truk820]

I'm having some issues starting my 'Duke.

When I turn the key over I hear a single click, then nothing. If I wait a few minutes and try again it might try to turn over, but maybe not. I checked the starter solenoid with the following instructions:

"4) Connect jumper from battery positive post to solenoid S-Terminal. If engine cranks, solenoid is not defective. Look for problems in the starter switch circuit."

Well, every time I touch the positive battery post what do you know...cranks right up.

How do I continue diagnosing the 'starter switch circuit'? Any ideas on what else it might be?

 

[Hedgehog]

Pull the wire of the solenoid post and give it a good cleaning. Also clean your battery posts. A little corrosion can prevent proper electrical contact. If that doesn't help a new solenoid isn't expensive and is easy to replace, they don't last for ever. Yes, I read your post. Sometimes there is enough line loss to prevent a somewhat weak solenoid from working properly.

 

[truk820]

Scrubbed the post / wires and have a new battery...still the single click.

I'll replace the solenoid tomorrow but if that doesn't help what are the next steps?

 

[Torxhead]

If you have voltage to the "S" terminal when you hit the starter, then you should replace the relay. The relay is grounded to the fenderwell, which should have contact to the battery negative. You could run a cable from the battery negative to the relay mounting bolt to ground it.

 

[truk820]

Torxhead - thanks for the info but I'm a little confused. Where/what is the relay, and what do you mean by 'hit the starter'?

(Sorry for the newbie lack of terminology)

 

[Torxhead]

The starter relay or solenoid is what sends the current to the starter. When you "Hit the starter" I mean turn the ignition key as you were starting the engine. That sends 12 volts to the "S" terminal at the relay to rotate the starter. I think everybody should have an electrical schematic of their Jeep. If you have questions then ask.

 

[truk820]

(I'll see if I can find the starter relay in my wiring diagram as well)

 

[mtnwhlr]

Torxhead - thanks for the info but I'm a little confused. Where/what is the relay, and what do you mean by 'hit the starter'?

(Sorry for the newbie lack of terminology)

this is what he is talking about. Busadaves pic

 

[truk820]

Is that a starter solenoid? If not I don't have anything that looks like that on my fender ()

I took a voltage reading at the "S" terminal and when I turn the key it's getting ~7.5V, not 12 like I imagine it should. Is that normal?

Here's a picture of the solenoid:



I bought another solenoid that I was going to install tomorrow but if I just identified the problem then...

 

[mtnwhlr]

Is that a starter solenoid? If not I don't have anything that looks like that on my fender ()

I took a voltage reading at the "S" terminal and when I turn the key it's getting ~7.5V, not 12 like I imagine it should. Is that normal?

Here's a picture of the solenoid:



I bought another solenoid that I was going to install tomorrow but if I just identified the problem then...

Yes that is your solenoid, sorry I thought in '81 it would be on your fender like the pic I posted.

 

[truk820]

No problem thanks for posting the pic though, I appreciate the help. Needless to say I'm lost without this forum.

 

[Torxhead]

No problem thanks for posting the pic though, I appreciate the help. Needless to say I'm lost without this forum.

Me too!, I had forgotten about that style of solenoid also, So that means the whole assembly usually gets replaced if that is the problem.

 

[truk820]

Well...no good news. I replaced the starter solenoid and got nothing. No click, no nothing. I quadruple checked grounds and clean connections. The only thing that I may have been doing wrong is this solenoid had 4 posts and my other one had 3. I left the "I" terminal empty - maybe that was it? Anyways I swapped the old one back on and got the usual single click, then it cranked, then single clicks again. It's weird that I'll intermittently be able to crank the engine, there's just no rhyme or reason so when I'll be able to do so.

Also, I pulled the wire off of the S terminal and tested its voltage again. Last time when I tested it I was testing at the post of the starter solenoid, not on the actual wire. The wire carries the proper 12V when I hit the starter. For kicks I tried jumping the solenoid again and it cranked right up.

I'm frustrated here and think I'm going to pull the starter and start fresh. Maybe that will work it the problem out? Fingers crossed.

 

[Hedgehog]

The starting system is relatively simple. When this sort of thing happens its usually the solenoid. The solenoid is really just a big switch made to handle very high loads, or amperage. You put 12v on an electro magnet, the magnet creates a field and tries to push a metal bar in the field away. The metal bar hits the end of the solenoid which is actually a contact point, with enough force to reduce or eliminate the arcing that occures when high amperage moves through a switch. Sometimes the switch becomes burnt reducing it's ability to make a clean circuit and you only get the click with little to no electricity flowing. I.E. it's time for a new solenoid. Occasionally the solenoid will arc and weld itself to the contack creating a situation where the started doesn't disengage, thats when hitting the solenoid with a hammer works, I.E. it's time for a new solenoid. When you have a low battery the solenoid will click rapidly, why? There isn't enough power in the battery to turn the engine over, but all the available power flows into the starter robbing the solenoid of power to keep a closed circuit and the solenoid stops working, but suddenly there is power and the thing CLICKS again. In your case it sounds like you are losing power from the switch to the solenoid to the point where the circuit isn't closing properly. Or wintertime temps are making the solenoid sluggish, again making a poor connection. Your starter works, your switch doesn't, the problem is in the switch side not the starter. AAAnnnddd that's my story and I'm sticking to it.

 

[truk820]

You may have just saved me a trip to Autozone

When I hooked the new solenoid up I had:

S terminal to light blue wire (same as before)
I terminal to nothing

This got me nothing. I swapped the light blue to the other post (not labelled but I assume the I terminal) side and nothing. I jumped to both posts to the battery like I did before and nothing. I also used a jumper to ground the solenoid to the battery..and nothing. Could the solenoid be bad??

I'm aaaaalmost to the 'I'm hopeless I'm willing to try anything' stage but for the extra $40 I might just go for the entire starter tomorrow (they're out at my local shop anyway)

and thanks for the info, much appreciated.

 

[truk820]

Alright, have some good news. I tried everything but replacing the starter and no dice, so I took a leap and replaced the whole thing. It immediately starts cranking! VICTORY

(well, kind of)

It still won't start though, after I replaced the cap, plugs and wires. I'm going to test for sparks while it cranks once I figure out how to do so.

 

[Hedgehog]

Easy, pull a spark plug, plug it in, lay it on the engine and crank'er over while watching for a nice solid spark in the spark plug. Not an end all be all because a weak spark has trouble in a high pressure environment like a cylinder.

 

[truk820]

Thanks - replaced the plugs, tested them and put them in. First turn of the key and it fired right up! Morale is high, thanks everyone!

 

[Torxhead]

Thanks for the update. So it appears that it was the starter. I like to run a ground wire from the battery negative to the closest point to the starter, since it does draw quite a load at startup.