CJ7 stutters and has no power in3rd 4th gear

CJ7 stutters and has no power in3rd 4th gear

HBCA92647

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Maui, HI
1986 jeep CJ7 4.2
i have this jeep that started running like :dung: when under a load and going up a slight grade. stumbling and stuttering. i have changed the fuel filter,fuel pump,coil,cap&rotor,distributor pick up coil, plugs are new and wires. with no Joy. i have pulled the distributor and made sure i was on TDC before timing. got it running but still have the same issue but a little worse. it has the stock carb, it starts up strong but when warmed up it really runs crappy. is it the carb?
any input would help.
 
I would say yes it is the carb sounds like it is time for a rebuild
 
1986 jeep CJ7 4.2
i have this jeep that started running like :dung: when under a load and going up a slight grade. stumbling and stuttering. i have changed the fuel filter,fuel pump,coil,cap&rotor,distributor pick up coil, plugs are new and wires. with no Joy. i have pulled the distributor and made sure i was on TDC before timing. got it running but still have the same issue but a little worse. it has the stock carb, it starts up strong but when warmed up it really runs crappy. is it the carb?
any input would help.

:)If you have established TDC and your timing is correct , maybe check two more things...........put your timing light on your motor and as you raise the RPM does the timing marks advance? If not you may still have a problem with the advance plate / curve in the Distributor...........and once the motor is HOT pull the air cleaner and make sure the Choke blade is straight up and open all the way...........if not that could be choking your motor for air.

:D:D:D:D
 
When it is running like :dung: with an ignition miss, it could be the ignition control module. An indicator would be that the module is hot to the touch. Another would be that it gets worse as the engine warms up.
 
thanks for the reply, yes the timing does advance and the choke plate in fully open. i will check the ECM and the advance curve a second time might not hurt.
 
Thats icm for ignition control module. The distributor pick up coil can make it run lousy also but I read that you have replaced that. As I recall there is supposed to be a 400-800 ohm resistance between the orange and purple wires at the pick up coil.
 
well, the carb has been re built, the ICM replaced with no joy. it is running better but still stalls and stutters when warmed up. sorry i have not posted anything sooner, and thanks for the replies.
 
If the carb was rebuilt, was the correct float level set? which could be an issue here.
 
yes i'm pretty sure the correct float level was set. Now that i have the jeep, it seems to be some type of electrical issue. the jeep will start up strong but after a few minutes if it touch the clutch pedal and move it around all my gauges will pin out and then the jeep starts to die. some how the ignition is getting grounded out. will the Nutter by pass isolate the engine from the rest of the jeeps wiring? i think i'm gona put the old coil,distributor pick up back in and see if some part i got was wrong or bad. is their some wire sending power to the chassy than could be hitting the clutch pedal.
 
I would hold off on the Nutter By-pass until you have your gauge issue solved. I'm not a fan of the by-pass since it prevents maximum distributor advance and fuel mixture operation in the carb from the computer. I would look under the dash and in the engine compartment for any wires that might be frayed near the clutch pedal and its linkage.
 
I would check my fuel tank. If it runs well when cold and sitting it could be that the junk (rust, etc) in your tank has settled but as soon as you start moving or there is more suction on the tank because of more fuel demand while moving it is pulling up particles which causes it to stall, the suction drops off, the piece blocking falls, fuel opens up, suction picks up..etc and it starts over again. I had this problem with a machine of mine...pulled up and cleaned out the tank and it ran like new.
 
i will look into the fuel possibility. i have been pretty good about buying good gas and changing the filter probably to often. the jeep was almost a daily driver and this issue just spiraled out of control. i am working on removing all the extra :dung:(electrical) that has been installed over the years. i need to have it ready to ship back to the mainland soon. thanks for all the advice.
 
It usually isn't a problem with the gas you are buying, it usually is if the PO let it sit and the condensation caused rust in the tank that flakes and falls down into the tank. Anytime I hear of these guys that find a jeep that has been sitting in a field or barn, drop that tank and clean it out...saves you headaches in the future. Good luck and see you when you get back to the mainland. :D
 
Well after a few days of looking at the jeep sit in the garage i thought i should get back to it. i removed every electrical add on that has been wired up to this thing. I finally got to the high- low beam switch, hit it and the lights went out and the switch started to get hot. traced all the wires up to the drivers light and BAM the radiator had grounded out the head light. re wired it up and no more spiking gauges and with the carb rebuilt she is running strong again. i want to thank all who had input on this issue. thanks again. :
 
Well i spoke to soon, the issue is still there. the jeep will run well for about 15min but when it get warmed up it starts loosing power and running poor. this has got to be something with the carb and the choke. the choke is getting voltage, and when warm the choke is still getting 11 volts. not sure if that is correct. also the choke plate is wide open when warm.
 
This is the FSM download:http://www.civilianjeep.info/84-86FSM/CJ-FSM-84to86.pdf, which can be a real pain to use.
On page B-12 in the service diagnosis section, there are suggestions for rough idle and stalling. None of these suggestions may apply to your issue, but could steer you in the right direction. Another possibility might be a defective computer, in this case the "Nutter Bypass" would disconnect operation from the computer to the ignition and carb. I would start by checking the deposits on the spark plugs to see if the carb fuel mixture is correct.
 
I have looked into the Nutter bypass and i am a lttle confused on the stepper motor adjust. if any body has some more info on the adjustment that needs to be made please let me know.
 
i went and did the Nutter bypass, it went pretty good and the jeep runs great. the engine does not stutter and has all the power through the gears. one question i have is the vacuum for the distributor is not there, when i hooked it up to the port noted in the wright up there is no vacuum. should i run it off another port?
 

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