2.8L 84 Bronco II idle problems
 

I just picked this thing up. It would not idle on the way home. It sat for 6 years so I thought the idle passages in the carb were gunked up. I cleaned the carb and replaced the fuel filter. I did notice the plastic arm on the choke was broke (I think for the fast idle). You have to give it a few pumps to start it and when its running the response time for it to rev down is long. I turned up the idle screw a couple cranks and it has a high idle and will make a clicking noise when it starts to die from some type of relay on the passenger fender. Any one got any ideas? I havent pulled the plugs or checked for codes. I'm at 6000ft elevation in Colorado. The idle screws are out 1.5 turns. I have read that they might need to be out more, thoughts?

Update. I have since opened up the idle air mixture screws a full 3 turns and it will rev down somewhat normal. I turned the idle screw down and it will idle but its very high. I have tried to lower the the idle to a normal level but it gets to a certain point and then some type of relay starts clicking on the passenger fender then it will die. I guess its stumped everyone thats read the post because no one has replied with any ideas. I have read that the idle air controller might be the problem. Does anyone know how it works? I pulled the plugs and they were gas soaked

is your joke opening up all the wat when it gets warm?

How did you clean the carb. a can of carb cleaner? or did you take it all apart and do it right, installing a rebuild kit while you where at it? Checking to be sure the float doesn't leak too.

If it sat for that long it would gum up the works bad, if "regular/unleaded" gas was used (and it probably was) it would be even worse!

Hey Ronev -

Any answers yet? I've got an '85 BII with the exact same problems. I'm also at 6000ft (although that shouldn't matter). Mine used to run fine, but it had to sit for about 6 mo. without running. It didn't pass emissions (just barely missed) so I bought a carb rebuild kit. It starts fine, but to get it to idle, I've got the two screws under the carb set so that it idles at about 1200 rpm or so.

The IAC on these old carbs is the lever that presses up against the throttle tab and attempts to increase the idle when it drops too low. You can see it work by observing the piston moving in and out while the engine is idling. Last year at this time, I disconnected it because it was keeping the idle so high it was ridiculous. It then ran perfectly.

Anyway, I'm still afraid mine is too rich. Anyone else know how to adjust the idle properly and what controls the mixture on these beasts?? My rebuild kit had everything that was replaceable including the power valve. It seems to run fine, but rich. What are the two screws at the base for?? Idle??

Thanks in advance - hope this bump helps.

Dr Z,
Sorry, no ideas yet. Not that it has any effect but I just picked up a distributer cap and rotor to put on it as well as some new plugs. When you rebuilt your carb did it run any better? Did you ever get it to pass emissions? I havent done anything with it yet, I have been reading through the haynes manual trying to pick up some ideas. I did figure out that the original choke power wire didnt have power so a previous owner ran a new one. I need to hunt it down and see if the fuseable link might be causing my problem. i'll keep you apprised of what I find out.
Ron

Dr Z,
I was changing the plugs and noticed that the o2 sensor isnt plugged into anything. I couldnt find the wire to plug it in. Where is yours connected?

Mine is a single wire (with a fairly big plastic plug) that seems to eventually go over to the passenger side fender in the area where the EEC box is located.

Got home tonight and fiddled with the idle some more until it got dark. My idle controller won't keep it running. It moves to prevent the engine from killing about a second after the engine stops...

Another thing I suspect is that I have a vacuum leak somewhere - it's about the only thing that explains such a high idle. I'll just keep debugging and looking for tips on various web sites... :-huh

how big is the ecc box? that idle controller is adjustable. If you look close it rides on an adjustable carriage with a spring. Also a quick question. On the front side top of the carb there is a 3/8? inch vacuum line that comes out and heads in the direction of the drivers side fender. It has some type of electronic valve. I noticed mine says "carb" on it with an arrow. Mine seemed to be pointed the wrong way, is yours? Ron

Sounds like a Vacum leak to me, i have an 84 here in Cali and I passed emissions, but I had to replace all the vaccum lines I could find, even those pesky little colored peices of crap. I would make sure you hook up that o2 sensor because it is a major park of how all the emission equitment works, espcially with feedback cylinoid on the back of our electronic carbs. The O2 sensore should run around the back of the motor to the sensor on the drivers side exaust manifold.

Thanks Canadianice - a vacuum leak is one of the things I suspect, and also possibly a bad float level after I rebuilt the carb.

Ronev - I'm on hold timewise until the weekend...any luck??

A vacuum leak is a very high possability especially since opening up your idle bleed (adds gas) helps. My B2 did everything you guys described. I found unplugging the TPS helped allot. I replaced the TPS and still had the problem so I think the computer or that mess on the right fenderwalll was hosed.

I finally did the DUraSpark conversion and have not had a problem since.

I did some looking and found the O2 sensor wire hidden back behing the motor. I hooked it back up but I havent fired it up yet but I'll get into over the weekend. Does anyone know what that thing connected to the front top of the carb. It is connected to the hose nipple pointed toward the drivers side. Mine has one of the two wire broke off. I'll get one at the junkyard I guess but I'd like to know what it is and if I have it hooked up in the right direction. Thanks for everyones input I'm still working on it

RONEV, where in CO do you live? If you don't live in metro Denver where they have the enhance emissions tests, do the duraspark conversion to the ignition system and get rid of all the old, unreliable and troublesome ignition & emissions equipment. I did it to mine and the truck runs much better at altitude, idles around 1200 and is reliable. The truck will pass the basic emissions test w/o the equipment, esp. since the guys running the emissions station aren't old enough to know what a carb is or what the original equipment on the truck was.

I'm up (elevation wise) in colorado springs. I went to a u pullit yard here and got some parts. I found an 84 ranger with the front end smashed in. The corners of the carb were broke off but it had a few parts on it I needed. The idle air mixture was out 3 and a have turns on the donor carb. The original choke and some other connecing rods on my original carb were bent and broken. I managed to cannibilize what I needed. I still have a miss but I noticed a couple plug wires had excessive corrosion on the cap side. I'll change those next and post the findings. Thanks for everyones input so far.