unknown electrical issue... - JeepForum.com

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post #1 of 8 Old 01-09-2010, 11:15 PM Thread Starter
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1981 CJ7 
Join Date: Nov 2008
Location: Oregon
Posts: 151
unknown electrical issue...

Hello all...'81 CJ7 258 I-6. Carter BBD non-feedback computer. Team Rush upgrade, and upgraded grounds to all major components. 8deg BTDC.

My CJ has had an ongoing issue with the choke (I think). I took it to some mechanics (before I started doing all my own work) and they seemed to fix the problem by disconnecting the Oil Pressure switch and putting a wire in the plug to connect both the slots together. I know this is my issue again. It's acting the same as it did before I took it to them. Oh, 4 years have passed since...

Should I buy a new pressure switch and try to hook that back up? My fuses look good and I've grounded just about everything with 4 gage wire. Every now and then my jeep will tease me by running VERY smooth. It's usually after it's been sitting for a few minutes. So, not cold, but not hot.

Once it warms up, back to the steady chugging and poor gas mileage. Is my issue the choke or something else? Once again, Help.

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post #2 of 8 Old 01-10-2010, 08:11 AM
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1982 CJ7 
Join Date: Oct 2009
Location: ca
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If the choke element is burnt out then the choke will stay on more less. After a good long warm up and its still sputtering and chugging see if the choke butterfly is closed at all in the carb throat,it should be wide open and take a bit of force to move it closed indicating the heat element is working,if not Id check there first. Theres also the possibility of linkage hanging up so dont forget to have a look at that as well.
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post #3 of 8 Old 01-10-2010, 08:38 AM Thread Starter
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1981 CJ7 
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Location: Oregon
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I also routinely get 15volts on my gauge when driving around with no electrical components running (lights off, heater blower motor off, etc...) Chugging, bad gas mileage and the whole nine yards...

When my jeep starts to run "great" it's right at or slightly below 14 volts with no load placed on it. This leads me to believe it's an electrical issue, but I don't know where to start looking?
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post #4 of 8 Old 01-10-2010, 09:19 AM Thread Starter
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1981 CJ7 
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Location: Oregon
Posts: 151
Could the voltage regulator be the problem? I found this replacement at Napa online. How/where would I put it?

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post #5 of 8 Old 01-10-2010, 09:25 AM
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1982 CJ7 
Join Date: Oct 2009
Location: ca
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From what you describe and from things that my CJ had I say you still have bad ground issues. I ran new lines from the chassis to the body and to the frame. Consider all lighting and the dash has its own grounds as well and regardless ofall the new grounds you might have run if the specific item,headlights,gauge panel has corrosion its still gonna act up. My oil pressure and volt gauge both dropped considerably after fixing all my ground issues. For one you can use a DVM to check the battery and see what voltage there is at the leads and compare to the gauge on the dash. At any rate IMO CJ gauges are very touchy as far as reaction when put under a load such as lights,heater,blinker are turned on.
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post #6 of 8 Old 01-10-2010, 05:11 PM
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1973 CJ5 
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'81 CJ uses an oil pressure switch to pull the choke 'OFF'.

The choke resets it's self in cold with the engine 'OFF' so when you start cranking,
The choke is 'ON'.

The current passes through the choke pot and pulls the choke 'OFF' as the engine runs and oil pressure comes up.

I would start by checking to see if you have power to the oil pressure switch, which you will find with two wires sticking out of it,
Find it just behind the ignition coil sticking out of the side of the engine block.

Turn the ignition switch to the 'RUN' position,
Probe the terminals in the CONNECTOR (not the switch) to find if you have power to one of them.

You do NOT have power to that connector with the ignition switch in the 'Run' position,
Check the fuse for the brake warning lamp and the cigar lighter.

With engine RUNNING, (oil pressure 'Up) check the switch to make sure it's 'Closed',
That you can get current through the terminals on the switch.

You don't get power through the switch, it's time for a new switch.

Then check the wire that feeds the choke pot.
You should have power there when the engine is running.

*IF*... You don't have power to that connector for the choke with engine running, you have a bad wire between switch and choke.

Use a 'Hot Wire' from battery to choke terminal,
Watch the linkage.
If it moves the choke pot is working...

I can't tell you if it's working 'Correctly', but it's working.

Your choke linkage doesn't move,
Then you need a new choke pot for the carb.

With the 'Hot Wire' your 'Mechanics' put in the oil pressure switch connector,
Your choke starts pulling 'OFF' the second you turn the key switch 'On'.
That reduces the amount of time the choke can work to effectively richen up your engine for cold starts.

It also activates the intake manifold heater even when the engine isn't running.
Besides being a load on the battery, it doesn't help you warm the engine up on cold starts.

The next thing I would have a look at is the carb it's self.

BBD carbs are really easy to plug up, and it's a $15 carb rebuild kit to make those 'Issues' go away.

Once the carb is rebuilt and you KNOW the choke/manifold heater are working correctly,
Then make sure your timing is correct.

Timing directly effects manifold vacuum,
And without correct vacuum your carb won't work correctly even if it's clean.

Once you check timing,
Make sure your curb idle and high idle setting screws are in the correct positions.

I will tell you one thing,
Most 'Chugging' complaints I get are solved by replacing cap & rotor, which if you haven't gone to a large cap and rotor,
Just humidity under the cap will cause cross fires, ground fires, and those show up as 'Chugging' of the engine.

Tall/Wide Brass terminal distributor caps, good plug wires are worth their weight in Gold for these old engines!
The small distributor cap the factory used just isn't sufficient for the higher spark energies created by electronic ignitions,
So doing the 'TeamRush' upgrade is always recommended.

Once you have the ignition lined out and adjusted,
Then move to the carb adjustments.
Make SURE you don't have any vacuum leaks,

Then move on to adjusting your carb for your climate/altitude, ect.
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post #7 of 8 Old 01-10-2010, 05:36 PM
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1978 CJ5 
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Location: Beach City
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What would be the chances that 4 years of directly connected (no oil pressure switch) heater elements being burned up? I know the 80's GM had that heater grid under the carbs, and if the engine wasn't running but the key turned to "Run" the lack of air moving thru the grid would melt them down. Do the intake heaters used on these engines have that issue?


1978 CJ5 5.0HO/T177/D300, '86 D30/D44 WT axles, 'glass body, 31x10.5 BFG A/T, TDK galv'd frame - DD and weekend toy

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post #8 of 8 Old 01-10-2010, 05:54 PM Thread Starter
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1981 CJ7 
Join Date: Nov 2008
Location: Oregon
Posts: 151
Thanks for the lengthy reply. Here goes:

Don't have power to the switch. Where is the fuse for the cigar/brake warning lamp? I just looked and couldn't find it.

I have checked the connections to the choke element and it is hot with the ignition on (with the oil pressure switch "hot")

I do remember the "mechanics" said they blew a few fuses before they disconnected my cigar lighter and hotwired the oil pressure switch. I've since tried to use the cigar lighter (hooked it back up), which may have burnt out the fuse again, but I don't know where this fuse lives.

I'm thinking of taking pics and posting them so you know what I'm talking about...

I have done the Team Rush upgrade and have noticed a slight improvement, but I think this electrical problem is overshadowing any improvement that may have happened.


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