Bogs down under load when running at Op Temp (hot)

Tiny
SPINSPIRIT
  • MEMBER
  • 1980 JEEP CJ7
  • 4.2L
  • 6 CYL
  • 4WD
  • MANUAL
  • 77,000 MILES
I am at my wits end. Bought this 1980 CJ7 6 cyl manual transmission, told it was problem free, and ready for a camping trip to Calif (Im in Fla.) On the way home, in Miami traffic, about 30 mins in, I noticed what seemed to be what sounded like low rpm missing/bogging/stuttering. Made my way to the right side of the road just in time she stalled. I thought it was something like fuel delivery, but filter and pump appeared fine, called the guy I just bought it from, of course he was surprised, but suggested I may need a new Ignition Control Module, as they get sensitive when hot and cause a bogging down of the engine. Let it rest for a few3 minutes, starts right back up, and off we go, only to experience it again within a few minutes of running. Took 9 hrs to get home. Replaced the ICM, issue continues to exists. Replaced typical plugs/wires/cap/rotor/coil/air filter. Problem persists. Replaced fuel pump, problem still persists. Rebuilt carb, problem still persist (Carter 1BBD). At a Loss, and my camping trip to California is about to go bust. I did notice that when I ordered my tune up kit, the plugs were a N-14LY, and what came out of the engine were a N-13L slightly smaller type plug. Again I noticed when focusing on the Carb, the Carter # 7230, which I researched as a 78-79 Model Carb? So I am confused now, 80 model, 79 components, either way, problem has been consistent. In a jist, she fires right up, idle in the low 700, 8 degree BTDC, revs fine, get on the road, 1st gear good, 2nd gear good, 3 gear usual good, 4th gear after a short while starts to bog down, like insufficient fuel supply or lack of spark. Sometimes will happen in 3rd gear before I even get to 4th. There are no Jeep shops out here in the keys, so I am feeling really dissapointed and stuck for the moment, just going round and round with the same thought loop. Btw, stuck on determine if I need a ballast resistor for the coil? Sure would like this to get to Medic if he's still aboard. Thanks
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Saturday, June 20th, 2015 AT 11:23 AM

7 Replies

Tiny
CARADIODOC
  • EXPERT
You said the fuel filter and pump "appear to be fine", but you didn't say how you determined that.

Everything you described is typical of a plugged or collapsing fuel pickup strainer inside the gas tank. That part commonly costs around five bucks. The clue is it doesn't cause a problem for the first ten to fifteen minutes, then it stretches out and allows fuel to pass again for just a few minutes before it acts up again.
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Saturday, June 20th, 2015 AT 6:32 PM
Tiny
CJ MEDEVAC
  • EXPERT
YO

HO

JUST SEEN YA!

DOES IT RUN LIKE THIS CONSTANTLY?

CAN YOU LAY THE HOOD BACK ON THE WINDSHIELD

SNATCH OFF THE BREATHER COMPLETELY

GIMME SOME PICS OVER AND OF BOTH SIDES OF THE ENGINE (TOO BIG [SIZE] WON'T POST) THE MORE THE MERRIER! MAYBE I CAN CATCH SOMETHING WRONG

YOU ARE EMISSIONS TESTED? WHAT ARE THEY TESTING, DO THEY GIVE YOU BREAKS ON YEAR AND OTHER STUFF? BEING A FLORIDA JEEP, ANY EXEMPTIONS?

CAN YOU TELL ME 'ZACKLY HOW YOU DID THE TIMING? STEP BY STEP

WE CAN TEST Caradiodoc's HYPOTHESIS PRETTY DARN EZ, WITHOUT DROPPING THE TANK (HOPEFULLY WE WON'T NEED TO) LET'S TALK THIS OVER A BIT BEFORE WE GET INTO THAT KINDA THING.

LET ME KNOW OF ANYTHING, THAT YOU KNOW OF, THAT MAY HAVE BEEN CHANGED OR MODIFIED ON THE ENGINE

AS SAID BEFORE, PICS WILL AID ME THE MOST!

THE MEDIC
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Saturday, June 20th, 2015 AT 8:29 PM
Tiny
SPINSPIRIT
  • MEMBER
The fuel pump and the fuel filter are brand new. I have not had time to access the fuel tank to check the inlet filter. Right now, I have come up with one other potentiality, and that is the Catalytic Converter which the previous owner says has never changed, that would be approx 14 yrs. I am surmising it is plugged enough to cause a back pressure buildup and a power loss.
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Monday, June 22nd, 2015 AT 4:02 PM
Tiny
SPINSPIRIT
  • MEMBER
MEDIC, thanks for chiming in. I will get pics taken this Wednesday. My work sch prevents me from having the time to do so otherwise.
Florida has no emission testing, so I have no results. The timing is just the basic steps of disconnecting the vac, and taking a reading 8 degrees BTDC, idle @ 700. She fires right up. The symptom does not occur until its been running a short bit (bogging down losing power, like no fuel or spark). I'm replacing the Catalytic Converter, as it is around 14yo and probably plugged enough to allow a back pressure to build up. I will put pics your way in cpl days when Im home. Thnks
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Monday, June 22nd, 2015 AT 4:08 PM
Tiny
CJ MEDEVAC
  • EXPERT
WONDERFUL!

NOT HAD A CJ IN MY 2CARGARAGE IN A WHILE

LOOKING FORWARD TO IT

THE MEDIC
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Monday, June 22nd, 2015 AT 7:10 PM
Tiny
BLAKEANTHONY97
  • MEMBER
I have the same issue, did you figure out what it was?
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Friday, December 18th, 2015 AT 6:45 PM
Tiny
CJ MEDEVAC
  • EXPERT
BLAKEANTHONY97

LET'S HEAR WHAT YOU HAVE DONE

WHAT YOU HAVE CHECKED (AND HOW)

WHAT HAS BEEN TAKEN OFF

MODIFICATIONS

WHEN DID IT RUN FINE IN THE PAST, WHAT WAS DONE (AND MADE IT RUN BAD)

MAYBE SOME GOOD PICS, WITH THE BREATHER REMOVED, HOOD AGAINST THE WINDSHIELD FRAME. LEFT/ RIGHT/ TOP VIEWS OF YOUR ENGINE

THIS IS MY FIRST USAGE OF THE SITE CHANGE, I MAY NEED SOME MORE HANDS ON TO FIGURE THIS VERSION OUT

THE MEDIC
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Saturday, December 19th, 2015 AT 7:33 PM

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