1971 M151A2 wont start

[Col Batguano]

I took off the air filter to the carb and confirmed there is fuel getting to the carb. Not a lot, I thought it would be gushing out more when cranking the engine. I removed one spark plug and reconnected it to the plug wire (Did not have a spare plug to test) and touched it to the engine and got no spark. Spark plugs look old. OK so what is next on the list to check ? Thank you for the help everyone. Rob

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[Hambone]

First, I would make sure you're getting 24V to the coil, You can test the coil with an ohm meter, then I would move on to the electronic ignition. These test can be done with distributor in jeep.
https://www.youtube.com/watch?v=EKhQ5sF ... Yo&index=3
https://www.google.com/search?q=m151+co ... 1lZ5c,st:0

[rickf]

Ok, So now I would move on to what Hambone is saying but before you open up the distributor take the wire off of the input to the distributor and check to see if you get 24 volts at that wire with the switch on. If not you have a wiring issue. If you have power there then pull the cap and see if you have power to the coil positive terminal. If no power then the capacitor behind the 4 screws coming into the distributor is bad. If you do have power then you need to see if the coil is good, Assuming you have electronic ignition you need to remove the wire from the negative terminal and then check for ohms on the coil. From one small terminal to the other will be 5-6 ohms on an original coil and around 11 ohms on a Chinese coil. From either small terminal to the center coil wire terminal should around 11,000 for US and 15,000 for Chinese. No reading on ether of these means a dead coil. If all good there then you can move on to the videos that hambone linked to. When was the last time this thing had a new cap and rotor? I have seen rotors burn through and the spark goes through the rotor and right to ground on the distributor shaft. Look at the inside of the cap for anything that look like a pencil line from the center post out to the edge of the cap.

[rickf]

Just went back to your first post and I see this is a 71? Does it have points?

[rickf]

And that plug looks fine, what I do not see is any gas on the plug to indicate it is getting fuel. Did you put your hand over the carb as I suggested? If you did and only got a little fuel you may have more than one issue.

[Col Batguano]

I have no idea when this MUTT had a new cap and rotor, I have owned her since last December and I will check to see if it has points. I did put my hand over the carb as suggested and got fuel on my hand but not as much as I thought would. Not sure if this helps or indicates anything but I did pour fuel into the carb and it still did not start. Also on the day she went tits up, it turned over and fired up for about 3 seconds then died and has not started since. I have never tried testing power to distributor or coil, it is all new to me. Will most likely need to buy the items to test these. Oh and glad that I can test this with the distributor in the jeep. Thank you

[rickf]

The only thing you need for the testing up to this point is a cheap multimeter. And if you get an Analog one with the old style sweep needle even better because you can use that on the negative terminal of the coil and crank it to see if the electronic or points are cycling the coil. You cannot see that on a digital meter. If you have no spark then no amount of gas will help. If you have points then they may just need cleaning. But since you have never checked in there since buying the vehicle it would be good to do a full tuneup on this thing. You will need to know if it is points or electronic first so you know what to get. I am going to assume the the valves have never been adjusted or timing checked since you got it?

[svramselaar]

hi

to test the low voltage side of the ignition points and electronic

take a testing light one side at the ground
if you have the distributor cover off put the light at the right nut at the coil
or take the big plug from the distributor cover out
put the test light at the small nut inside do not make contact with the cover
if you start the engine the light must flashing
if OK and no spark test the coil and other high voltage parts
take the ignition cover off
take a copper wire screw it with a eye at distributor side
bend the wire to the middle of the coil about 1/4 to 3/8 above the coil
start the engine and see if there is a spark
if not coil bad
if yes test the rotor arm
take a isolated wire from the center coil and hold it 1/4 above the rotor arm
let a person start the engine if it sparks rotor arm has a defect (short to axle )
if not rotor arm OK
look close at the cap for black stripes or cracks

if the light at the big bolt hole or the at the right side nut at the coil not flash an only lights up
points make no contact or electric module bad
if no light at all no power to distributor or the wire inside distributor broken
if it lights up at the coil left nut and not at the right side nut the coil is bad

george

[lpcoating]

While you're in the distributor, you should oil it per the LO. There are (2) oil locations.

Guy

[Col Batguano]

Hi All Got the distributor top off, pictures provided. Can anyone see anything wrong that stands out ? Also one of the spark plug cables is being very rude and not allowing itself to be removed from the distributor cap. Seems stuck pretty good, almost so that I'm starting to think its not suppose to come out. Is that true or is it just stuck and needs encouragement ? OK so my next mission is to confirm if the coil and dizzy are working correct ?

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[Horst]

All 4 ignition cables remove the same way. But, right now, don't fight it, it is not the problem.

So far everything looks right, I believe the ignitor was converted to electronic ignition at some point in time. You can see that this red cable shoe was squeezed between the body and the lid. There is also a overhaul data plate attached to the ignitor, maybe that's when the conversion happened.

Get yourself a test light and follow George's step by step troubleshooting.

Once the ignition system is diagnosed, repaired and the engine runs again, get also a timing light. A 12V timing light will work perfectly ok. Then set the timing as per the manual. As for every engine, correct timing is essential. But again, that is step #2.

BTW, a spare ignitor is what I carry with me on longer trips...

[rickf]

I agree with Horst, That is a Swiss Controls electronic ignition and the original for that year would have been a Prestolite, or points. If you look at an enlarged pic of the inside of the cap at the 10:00 position you will see a line. That is exactly what a carbon track looks like that will conduct power from a plug terminal to ground. That cap looks to be in good condition and unless you had a miss on only one cylinder that mark is not an issue. Do the tests either the way I said or the way George said, either one will give you the proper diagnosis.

[Col Batguano]

I agree with Horst, That is a Swiss Controls electronic ignition and the original for that year would have been a Prestolite, or points. If you look at an enlarged pic of the inside of the cap at the 10:00 position you will see a line. That is exactly what a carbon track looks like that will conduct power from a plug terminal to ground. That cap looks to be in good condition and unless you had a miss on only one cylinder that mark is not an issue. Do the tests either the way I said or the way George said, either one will give you the proper diagnosis.

What do you mean by a miss on one cylinder ? Thank you. Rob

[fowlercal]

Col B,

He means that when it was running, if you heard a rough idle or misfire, it would have been due to the possible crack in your distributor cap shown in your photos. Hope this helps,

Cal

[rickf]

Standing by the exhaust pipe you would hear a rhythmic dead spot. If you hold a piece of paper in front of the tail pipe it will slap against the pipe every time it misses. This is not the cause of your no spark condition unless that happens to be the plug you picked, even then you are not getting fire so proceed with the other tests. If you pm me your phone number I can call and walk you through all of this.
And squirt a little WD-40 in the hole where the plug wire is stuck. after a day or so you might be able to wiggle it out. You have to be careful you do not damage the inner conductor on the wire. Those wires are very pricey about now.