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Jeep cranks, but won't start

Tiny
CREWMASTER1
  • MEMBER
  • 1984 JEEP CJ7
  • 999,999 MILES
I have an 84 CJ7 with a 4.2L engine, carburated, 3 speed auto tranny. Aftermarket mods include nutter bypass, msd ignition, and alarm. Last week the jeep wouldn't even crank. Battery tested good, I replaced solenoid and starter. Read on forum, that if the neutral safety switch goes bad this will happen. So I ran a ground from solenoid to the fram and bypassed the NSS. Jeep started and ran great for a week. Then while driving on the freeway, I hit a minor bump and the jeep dies. Now it will crank over and start as long as I have the key in the start position, but as soon as I return the key to the run position it does. I checked the fuel delivery and the the mechanical fuel pump and filter seem to be fine because it pumps fuel out like a champ when I'm trying to start it and have the hose that connectes to the carb disconnected and running into a bucket. So, I'm assuming it has to do with the spark. I have a volt detector that lights up when a wire has voltage, but won't give me an actual number. When I test the positive wire to the coil it lights up, but when I try to test the spark-plug like wire from the coil to the distributor, nothing.I bought a new coil from a local auto store and the same thing happens. I have checked all the grounds and fuses I can find, nothing abnormal.
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Sunday, July 22nd, 2012 AT 6:21 AM

33 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check and test the distributor pick-up coil and also the ignition control module and return with your findings.
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Sunday, July 22nd, 2012 AT 7:00 AM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
How do I check these?
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Sunday, July 22nd, 2012 AT 7:14 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You need a DVOM to perform the tests on the distributor pick-up coil in the distributor, also a ignition module tester to check the IC Ignitor
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Sunday, July 22nd, 2012 AT 11:10 AM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
FOR SURE, ADVANCE AUTO CAN CHECK YOUR MODULE

SEE MY ANSWERS AT THIS POST

https://www.2carpros.com/questions/1977-jeep-wagoneer-77-360-begun-dying-random-only-happens-on-longer-drives-say

I HAVE NO IDEA WHAT YOUR ALARM DOES (IF IT AFFECTS IGN OR NOT)

THE REASON YOUR JEEP "BUSTS OFF" WHILE CRANKING IS BECAUSE IT IS GETTING FULL BATTERY VOLTAGE FROM "I TERMINAL" ON THE SOLENOID.....LIKE IT SHOULD!

SOUNDS LIKE YOU HAVE A PROBLEM BETWEEN THE ACTUAL IGN SWITCH AND THE COIL

YOU MAY HAVE A SHORT, MAYBE MELTED WIRES ON THE MANIFOLD--SHAKE YOUR HARNESS WHILE SOMEONE ELSE CRANKS

GOT THE CORRECT COIL?......."FOR USE WITH EXTERNAL RESISTOR"????

RETURN WITH NEWS.....INVESTIGATE OTHER CJ 5 AND 7 POSTS IN THE 2CARPROS FORUMS

TRY THIS TEST TOO (PIC 2) THIS SHOULD FIRE UP YOUR JEEP WITHOUT THE POSSIBILITY OF A SHORT IN THE SYSTEM KILLING IT.....DEPENDING ON RESULTS, WE MAY KNOW WHERE TO CONCENTRATE OUR EFFORTS

WAITING ON YOU

THE MEDIC
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Sunday, July 22nd, 2012 AT 2:26 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
GUESSING IT'S NOT IN THE DISTRIBUTOR, AS IT DOES TRY TO START WHILE IT'S TURNING OVER

I DO HAVE PICS TO TEST IT---IF NEED BE

I'LL BE BACK ON AROUND 19:00 HRS EASTERN TIME, AFTER WORK

THE MEDIC
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Sunday, July 22nd, 2012 AT 2:37 PM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
I can definitely have the ICM checked, but the vehicle has a MSD ignition wired in and the harnass fromt he ICM is disconnected. I tried reconnecting it because someone said this can function as a backup ignition and that didn't seem to help.
The coil I bought said "use with electronic ignition" It is a BWD E71P coil. It doesn't specify "external resistor, " but I looked it up and it is compatible with my model jeep/engine per the website. I did a google search and it sounds like this does work with the external resistor.
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Sunday, July 22nd, 2012 AT 5:10 PM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
ICM checked out fine. The connections have some corrosion that I will clean before reattaching. The ICM they had for sale was crappy and since mine worked I didn't want to buy it there.
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Sunday, July 22nd, 2012 AT 6:43 PM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
I went and bought a new coil that specifically says for use with external resister. This didn't make any difference. I tried the alligator clips from the battery pos terminal post terminal of the coil and then negative alligator clip from neg coil to the coil connector thing on your picture #2 above, got nothing with the key in the off and run position (didn't advance key to start position with this hookup). The coil was connected to the distributor when I did this test (is that correct?)
Autozone said they can't test distributors. Should I just replace?
Anyone know a good jeep mechanic in the Seattle area?
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Sunday, July 22nd, 2012 AT 10:03 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
I VISITED FT. LEWIS 6 TIMES, IN THE '80s, TRAINING WITH 2ND RANGER BATTALION (I WAS IN 1ST RANGER BAT, IN SAVANNAH, GA). SO YOUR BESTUS JEEP JEEP GUY IS BACK OVER HERE ON THE EAST COAST!

LET'S GET A "KEY ON" VOLTAGE TEST ON THE POSITIVE SIDE OF THE COIL---SEE PIC 1---YOUR READING DOES NOT HAVE TO MATCH MINE!

THEN HOOK UP LIKE 2ND PIC---TURN KEY TO "START". DOES IT CRANK UP AND RUN?

SEND PIC OF NEW DISTRIBUTOR AND ANOTHER OF IT'S WIRING COMING OUT OF IT

SO FAR YOU SAID IT WILL BUST OFF AND RUN, WHILE THE KEY IS IN START

THIS HAS ME "ASSUMING" THE DISTRIBUTOR IS GOOD---THE MODULE--IS GOOD----FUEL IS GOOD

FOR NOW---LETS GET IT HOOKED BACK UP, JUST LIKE IT WAS, WHEN IT WAS RUNNING

CHANGING THE FACTORS---REVERTING STUFF BACK LIKE ORIGINAL---MODIFYING STUFF---INVENTING NEW COMBINATIONS----MAKING UP YOUR OWN TESTS----STABBING AT STUFF AS YOUR BUDDY (WHO IS MORE LOST THAN YOU) SUGGESTS TO DO

. WILL ONLY MAKE IT HARDER TO TEST AND DIAGNOSE, WE SORTA NEED TO METHODICALLY CHECK STUFF

I HAVE NOT FULLY RULED OUT A FUEL PROBLEM. BUT WE WILL GO THERE IF NEED-BE

JUST GOT NEWS THAT MY MAMA IS HAVING CAR ISSUES--30 MILE TRIP---I'LL BE BACK AS SOON AS I CAN!

THE MEDIC
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Sunday, July 22nd, 2012 AT 11:15 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
STILL WAITIN' ON YOU!

I WENT AHEAD AND LOOKED UP YOUR NSS....IS THIS IT BELOW?

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_neutral-safety-switch-back-up-light-bwd_18971592-p?searchTerm=neutral+safety+switch

YOU CAN EZily TEST YOURS BY REMOVING IT AND ACTUATING THE "BALL" WHILE RUNNING A CONTINUITY TEST ON THE TWO TERMINALS.....1ST & 2ND PICS SHOWS THE PROCESS......IF YOU CAN UNDERSTAND MY HILLBILLY HOMEMADE PICS

IF IT DOES SHOW UP BAD, IT'S BEST TO REPLACE IT--"SAFETY" IS PART OF IT'S NAME......IT AIN'T REAL EXPENSIVE EITHER

MY VERY 1ST PIC SHOWS BYPASSING EVERYTHING AND RUNNING THE IGN OFF OF THE BATTERY

THE 3RD & 4TH PICS DOES THE SAME THING EXCEPT WE ARE LEAVING THE SUSPECTED "BAD" KEY CIRCUIT INCLUDED.....SEE IF THIS WILL MAKE IT RUN

I NEED SOME FEEDBACK---ESPECIALLY THE VOLTAGE AT THE POSITIVE SIDE OF THE COIL W/ THE KEY ON! (FROM MY LAST ANSWER)

THE MEDIC
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Monday, July 23rd, 2012 AT 3:41 AM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
Alright, I need to go buy a voltage meter. All I have is the yes/no 12v light meter. No actual reading. I have some pics to help you see my wiring and set up. In my possesion I have a new ICM and coil, but have not installed either because I want to FIND the problem before I add a bunch of confounding equiptment. Here are some pics. Pic 2 shows where the old ignition was disconnected and a newer system was spliced in. The jeep has the nutter bypass (which I believe bypasses the ECM) and it has an MSD. The alarm I mentioned does have an ignition block, but it doesn't allow the vehicle to crank, I have checked the alarm connections and the vehicle cranks so I don't think it is related to the alarm.
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Monday, July 23rd, 2012 AT 6:09 AM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
I hooked up the alligator clip wires like you showed me in pic#2 a few posts ago (bat direct to coil, etc) got nothing (tried with the old and new coil, no difference). Cranks, but no start. I'm headed down to buy a voltmeter.
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Monday, July 23rd, 2012 AT 6:30 PM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
So, I got a volt meter (pictured below) and I hooked the negative up to the battery negative and the positive on the positive side of the coil. When the key was in run there were 0.450 volts, and when it was cranked to start it shot up to like 60. This doesn't seem right, but I did it several times.
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Monday, July 23rd, 2012 AT 10:55 PM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
I did it again, just because I couldn't believe that number and it is 0.45-.5 VOLTS when the key is in the run position and 40-60 mVolts when the key is advanced to the Start position. Not sure what to make of all that. I charged the battery up today to make sure we were working with a full 12V and we are.
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Monday, July 23rd, 2012 AT 11:01 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Do you have battery voltage at the coil positive terminal when key at run position?
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Monday, July 23rd, 2012 AT 11:55 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
OK BOSS

ONCE AGAIN---PUT EVERY THING BACK JUST AS IT WAS WHEN IT DID RUN, DAYS AGO (COIL AND ALL)

IF IT RAN THEN---WE CAN FIX SOMETHING AND MAKE IT RUN NOW!

I SORTA DON'T UNDERSTAND THE ADVANTAGE OF THE NEW DISTRIBUTOR?

I KNOW THE MODULE IS BUILT IN. SEEMS SORTA OUT OF THE ORDINARY/AND HARDER TO WORK ON IT NOW---I FEEL SURE IT'S MORE COSTLY TO REPLACE THE STUFF IT HAS TO USE. BUT THAT'S JUST ME!

LETS HAVE THE MFG/NUMBERS OFF OF THE COIL YOU HAVE BEEN USING---MAYBE I CAN FIND THE OHM VALUES WE NEED FOR TESTING IT

SEE IF YOU CAN HELP ME KNOW THE DEAL BETTER USING MY PICS

THE MEDIC
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Tuesday, July 24th, 2012 AT 1:37 AM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
Wow. Think I can just fly you out here?
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Tuesday, July 24th, 2012 AT 5:07 AM
Tiny
CREWMASTER1
  • MEMBER
  • 18 POSTS
Here are some pictures from the instillation instructions that came in a large binder when I bought the jeep. The current coil on the jeep looks almost antique (probably the original), I don't see any markings on it. Will check again in the AM. I have everything currently set up as it was when it was running and I have not installed any new parts. I just have to believe it is some damn electrical connection given that we hit a bump and it instantly died. Since then, no starting. Enjoy the pics. There is a part on the sheet I have says "one added feature of using this stand along ignition is you can simply unhook the factor coil connector, distributor connector and module power connector and tape them over. This will give you a 'back up' ignition system in the event the CDI module ever fails! Simply untape the existing connectors and plug the factor hardware back in a drive away!" I of course tried this and it didn't work.

What do you think is up with only getting 0.5volts to the positive terminal of the coil with the key in the run position and then getting only 500milivolts (which I guess is the same at 0.5volts. Not sure why it reads differently on the volt meter) when the key is cranked to the start position.
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Tuesday, July 24th, 2012 AT 6:12 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
0.5 volts won't tickle the coil-run a wire from the positive terminal of the batt. Straight to the coil's positive terminal and check for spark at the coil wire disconnected from the distributor
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Tuesday, July 24th, 2012 AT 9:11 AM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
LOTS ON MY PLATE TODAY

8 YEATS AGO TODAY---I SORTA GAVE MYSELF TO THE LITTLE OLE CAROLINA GAL, WHAT A TREAT FOR HER!

GOTTA WORK TILL NOON

BEEN A WEEK SINCE I DROVE WILLY TO WORK.I FEEL SURE IT WILL HAVE TO RAIN, EVEN THOUGH THE CHANCE IS SLIM TO NONE. MY CANVAS TOP IS FINE WHILE DRIVING, BUT IF IT PUDDLES ON TOP IT LEAKS PRETTY GOOD, DESPITE THE 10 OR MORE THOMPSON'S WATER SEAL TREATMENTS I HAVE GIVEN IT!

ICING ON THE CAKE. HER 100 YEAR OLD GRANNY RETURNED TO HEAVEN A COUPLE OF HOURS AGO

I'LL BE TAKING MY LAPTOP AND A FEW MANUALS TO EDGEFIELD, SC AND ATTEMPT TO STAY OUT OF EVERYBODY'S WAY, WHILE THEY DO THEIR THING

I'LL GET BACK TO YOU SOON

LETS CHECK FUSES AND CONNECTIONS AGAIN---HAVE YOUR PAL CRANK WHILE YOU SHAKE YOU WIRING UNDER THE HOOD

POS BATTERY TO POSITIVE COIL SHOULD GIVE YOU IGN POWER AS IN MY PICS IN MY LAST ANSWER.

SEE YOU LATER TODAY

THE MEDIC
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Tuesday, July 24th, 2012 AT 10:58 AM

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