Spankrjs 1985 Spring Special CJ-7

[spankrjs]

Took some of the top parts off the carburetor so I could remove and clean the idle tubes.

Reference picture for me:



Took this top plate off to take a look, everything moving freely, no debris in here, looks OK.



Take these parts off:



Then you can get to the idle tubes.



Two screws and the entire venturi cluster comes out.



NOTE: I also removed and reinstalled the little check ball to blast out a few more ports with carburetor cleaner. Be careful with this, very easy to drop it down into the intake/engine!!

Using torch tip cleaning kit to check/clean the idle tubes for obstructions.



Blast carburetor cleaner through the tiny port inside the big circle. One for each tube. This is how fuel gets inside the brass tubes.



Blasted out all the little ports in this part with carburetor cleaner, too.





Make sure to reinstall the little check ball before reinstalling the removed parts. Be careful!!



Then reassembly.

 

[spankrjs]

Good news/bad news: no real gunk or varnish observed, no blocked idle tubes or ports that jumped out at me.



Restart took a bit of effort, all the fuel and carburetor cleaner flooded the engine when I was screwing around. Finally started up, idled like crap for a bit, finally cleared up. Quick test drive, maybe marginal improvement.

Little bit more screwing around, unplugged the vacuum advance, engine did not immediately drop RPM which I thought was odd? After a few seconds RPM would drop. Vacuum advance hose definitely pulling. Plugged that hose back up, unplugged the 4"/10" vacuum switch and drove around. Not a good idea, you have to really baby the throttle to keep the engine from falling flat on its face. So, just assuming that thingy is doing what it is supposed to. Plugged it back in, another quick drive, a bit better. Drove some more, sometimes almost no issues, then they would come back. Very intermittent.

I improved the situation or it improved itself, at least it is not violently bucking/surging during light throttle anymore, but the stumble is still there.

Sprayed brake parts cleaner around carburetor and intake, no vacuum leaks were found. Maybe a vacuum hose leak somewhere?

Things Jeep does perfect:

Starts right up
Shuts right off (no run on or dieseling)
Idles perfect
Choke working properly
Sol-Vac working perfectly
High speed operation perfectly
Heavy and light acceleration perfect

Things Jeep does not do well:

Steady light throttle to maintain constant speed, slight surge or buck. Better but still present. From 5 -40ish miles per hour.

The same buck/surge is also felt while decelerating, either with foot 100% off pedal or normal slow lifting of foot off pedal to slow down with vehicle in gear.

Did not notice a "light show" from spark plug wires with hood up/engine running outside in the dark.

So, maybe a carburetor blockage that is slowly working it's way out?

Maybe a slight vacuum leak leaning out mixture?

Maybe idle mixture set a hair too lean (was not a problem 6 years ago).

Maybe timing off (was not a problem 6 years ago)

Maybe vacuum/mechanical advance not working properly in the distributor, maybe sticking? Did have this issue 6 years ago.

More work/diagnosis needed, that's it for now.