Mechanics

CRANKS, BUT WON'T START

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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Crewmaster1
July 22, 2012.



Check and test the distributor pick-up coil and also the ignition control module and return with your findings.


Rasmataz
Jul 22, 2012.
How do I check these?


Tiny
Crewmaster1
Jul 22, 2012.
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


Rasmataz
Jul 22, 2012.
FOR SURE, ADVANCE AUTO CAN CHECK YOUR MODULE

SEE MY ANSWERS AT THIS POST

http://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


Tiny
CJ MEDEVAC
Jul 22, 2012.
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


Tiny
CJ MEDEVAC
Jul 22, 2012.
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.


Tiny
Crewmaster1
Jul 22, 2012.
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.


Tiny
Crewmaster1
Jul 22, 2012.
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?


Tiny
Crewmaster1
Jul 22, 2012.
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


Tiny
CJ MEDEVAC
Jul 22, 2012.
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


Tiny
CJ MEDEVAC
Jul 23, 2012.
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