carburetter icing?

[Jerry]

I assume the carb heater is broke. Is it possible to repair? Probably not! I'm guessing it's just another thing I'll have to put up with because I won't be able to get a replacement part :(

Thanks, Luke (Losing faith & getting pissed with never being able to get parts for his Comanche :headpop: )

 

2.8 V6 BTW

[86FUBAR]

If u could discribe the icing problem better that would be great , but depending on what ur smog/emissions testing consists of u might be better off getting a webber carb conversion kit (which are made specificaly for the jeep 2.8) and its a bolt on kit . cost is between 400 and 500$ i believe.

http://www.redlineweber.com/html/kits/k490.htm

[Jerry]

If u could discribe the icing problem better that would be great

Thanks for the weber info Fubar. To describe - It runs great and idles fine in warmer weather but as soon as the temp drops (around 1degC this morning) it stalls at idle. Eventually after a while of driving (25mins or so) it gets warm enough and runs OK. My local mechanic suggested it was probably icing when I described the problem to him. The only time i've seen the temp gauge rise above the first mark after the blue is when pulling the camper up some hot valley roads. Do they all run that cold? I have replaced the thermostat BTW. I've now got a piece of board covering 3/4 of the radiator to try and get it to warm quicker but it hasn't made much difference :dunno: Is it possible to get a new carb heater?

Cheers, Luke :thumbsup:

[summerinmaine]

MJs have carbs? Who knew? :dunno:

[mvusse]

The 2.8 V6 does.

 

The 2.5 I4 is throttle body injection, which some people mistake for a carb.

 

But I have never heard of a carb heater. A lot of vehicles circulate coolant through the intake manifold, though, and in cold climates vehicles have engine block heaters.

 

And with a cold intake, gasoline vapor condenses on the sides of the intake manifold. This is why chokes exist (more fuel/less air to make sure what's left of the mixture is still rich enough when it gets to the combustion chamber) and fuel injection systems meter more fuel before the engine reaches operating temp (and the O2 sensor starts working).

[Joop]

What exactly do you mean with "carb heater"?? The electicaly heated automatic choke or the flap in the airfilter box that sucks hot air from around the exhaust manifoild at when air temperature drops??

 

Neither way, i think i know what your problem is: The auto choke recives 12V power and slowly starts to turn itself off as soon as you turn on the ignition. After a while it will be completely off, and at the same time the engine temp should have risen enough for it to run and idle well unchoked. You say your engine is running cold. This means that after, lets say 5min of driving, the chocke would be turned off, but your engine temp is still to low. Wich result in rough idle and/or engine stalling. On hot days this problably won't be a problem.

 

I would suggest that you investigate your low engine temperature further, any good running engine should reach running temp in less than 25 minutes, even in cold weather. Yor brand new thermostat might have a fail or not the required opening temperature. Time to get another one??

 

Or even better...do as 86fubar says! Thrust me, its worth it!!

[Jerry]

Thanks for the responses guys. I guess further investigation is required to make sure I've got the correct facts at my finger tips :typing: I'm new to Jeeps and I don't know any details about my engine yet. It was simply the first car to come along when I was looking to buy one after moving to :Canadaflag: ! In fact it found me not the other way round :wavey: No one else I've met seems to know the 2.8 V6 either! Is it a General Motors engine? The guy in my local shop thinks there is a flat heater element between the carb and the manifold. There is some wiring down there suggesting this may be the case but I'll have to get it apart to know for sure. One more question about the cooling system ..... what could be keeping it running so cold other than a broken thermostat? :dunno: It's had two new ones since I got it. One I replaced and the other the garage replaced as it was still running cold!

 

:cheers: :cheers: :cheers:

[Pete M]

Yes, the 2.8L is a GM engine (that Jeep borrowed until their 4.0L was ready).

[carnuck]

The base gasket for the 2.8L V6 has a heater built into it (Chev used them in Citations, etc about '80 to '83) It was their answer to Mopar's "Leanburn" system. I would look for a late model 2.8L or 3.4 from an S10 and score the TBI system (only 2 injectors and VERY reliable!) Got the whole system from the local Junkyard here ('88/'89 S10, Blazer or Camaro with 2.8L IIRC) for $100 (harness, computer, intake, TBI and dist) and it was pretty much all under the hood. That was a couple years back.

I know several of the NAXJA guys have done the swap with writeups but I haven't been there for awhile.

 

 

PS: There are at least two 2.5L '86 MJs running around with a factory carb. One is in Alaska.

[FxRacing282]

The base gasket for the 2.8L V6 has a heater built into it (Chev used them in Citations, etc about '80 to '83) It was their answer to Mopar's "Leanburn" system. I would look for a late model 2.8L or 3.4 from an S10 and score the TBI system (only 2 injectors and VERY reliable!) Got the whole system from the local Junkyard here ('88/'89 S10, Blazer or Camaro with 2.8L IIRC) for $100 (harness, computer, intake, TBI and dist) and it was pretty much all under the hood. That was a couple years back.

I know several of the NAXJA guys have done the swap with writeups but I haven't been there for awhile.

 

 

PS: There are at least two 2.5L '86 MJs running around with a factory carb. One is in Alaska.

2.8 camaro is MPFI. has 6 injectors, not very important but.. i have one sitting inmy yard that going to the scrap yard next week. it was 60 degree heads and i believe the truck version has 90 degree. well if it is 60 ill sell y the intake manifold with the TB injectors and crap that goes with it.

[86FUBAR]

ya my 2.8 had the heater on it but i ditched it because it is un need (for me anyway) and its one more thing to slow the airflow going in that was just in the way. Are u sure u even have one because too my knowledge the only ones that were equiped with the heater were the rochester E2SE (electronic controled carb / califorina models) most all others just had the 2SE (non computer controled) and u being in BC i would gues that u have the 2SE ,Pray that u have the 2SE as there is much less crap on it .

[Eagle]

What exactly do you mean with "carb heater"?? The electicaly heated automatic choke or the flap in the airfilter box that sucks hot air from around the exhaust manifoild at when air temperature drops??

 

Neither way, i think i know what your problem is: The auto choke recives 12V power and slowly starts to turn itself off as soon as you turn on the ignition. After a while it will be completely off, and at the same time the engine temp should have risen enough for it to run and idle well unchoked. You say your engine is running cold. This means that after, lets say 5min of driving, the chocke would be turned off, but your engine temp is still to low. Wich result in rough idle and/or engine stalling. On hot days this problably won't be a problem.

 

I would suggest that you investigate your low engine temperature further, any good running engine should reach running temp in less than 25 minutes, even in cold weather. Yor brand new thermostat might have a fail or not the required opening temperature. Time to get another one??

 

Or even better...do as 86fubar says! Thrust me, its worth it!!

^^^

 

What he said, exactly.

 

This isn't a "Jeep thing." Carburetor icing is what happens to airplanes flying at high altitude in winter. I have never heard of a carburetor heater for an automobile, and I'm old enough to go back to when chokes "knew" when to open up by a coil spring in a can, not by an electric heater element. I've owned several cars with manual chokes. I have never, EVER encountered "icing" of a carburetor in an automobile.

 

Remember that the function of the thermostst in a car is to keep the temperature UP, not down. Some genius may have put a low-temperature thermostat in your MJ, or even removed the thermostat entirely, thinking it was a good idea. It isn't.

 

Your first step should be to buy the correct thermostat for your engine and install it.

[carnuck]

Before I put the hot air hose from the exhaust manifold to my aircleaner I had the BBD in my '82 Spirit ice up a LOT! Depends on weather and moisture content in the air!

[jtdesigns]

Honda's have a device called the FITV (Fast Idle Throttle Valve) what it does is basically use the engine's coolant temp to control a orifice that lets a little air into the throttle body to keep idle up until it reaches a warmer temp. As far as the 2.8 I would think that if you had any kind of coolant line entering the carb anywhere would be the same type of deal. I could be way off base, but I never seen a carb with a coolant line going into it. I have seen a preheat tube that comes off the exhaust manifold which uses a vacuum diaphragm to open and close. Your's may be missing? Another thing could be the valve maybe stuck, or inop. I have also seen engine block blankets that wrap around the engine in low temp areas to keep the engine toasty. I would think if you have the rad's airflow cut off it should keep warm pretty good. How cold is it there?

[carnuck]

I've seen heated intakes on Jeeps and Chevs (others too) but not carbs. Mitsubishi had hot water passing through it.

[JeepcoMJ]

my answer to the 2.8...the buick 3800

[deziped]

Sounds to me like he doesn't have a tube running from exhaust masnifold to air cleaner to direct warm air to carb. I can't count the cars I have bought that have had that tube thrown away for one reason or another. And every one of them in cold climate had the carbs ice up at temp 40 and lower to the the velocity of cold air being sucked in which lowered the air temp to below freezing. and blocked up the carb nozzels. As soon as the heat tube was installed again as oriiginally intended they never froze up. You probally using an aftermarket air filter system which SUCKs in the winter time at high altitudes.

[Jerry]

Plenty of opinions on this subject! :yes:

 

The pipe coming from the manifold is in place. The airbox has yet another vacuum operated gate in it to direct air flow from either up front or around the manifold, maybe that is stuck and only feeding cold air.

 

For reference I am a biker too and I know about the carb ice thing from the old 80's Kwakers

There is one big problem with these Kawasaki's, and its a problem all the late 1980's Kwaks had: they suffered from Carburetor Icing. As fuel formulations changed and manufacturers improved the quality of the vacuum in the intake tract, they stepped on a hidden problem: the water in the fuel froze out in the intake tracts. If it happened badly enough the engine would stall, even from high speed. There are several fixes including fuel additives, carburetor warmers, and body panel alterations. The "summer" of 1985 was miserable, it rained most days, with the high humidity I suffered terribly from constant stalls. The bike would run roughly, then draw to a standstill. The engine would run but would be so feeble it could not pull the bike. Turning off the engine for a few minutes was all that could be done. I added cardboard panels leading back from the radiator to cover the carbs. This helped. It looked a real mess after a winter or two, though. Eventually, in 1998, Kawasaki were forced into a rare motorcycle recall. They replaced the carburetors with items that had engine coolant flow ways drilled into the bodies. As my bike was an early model, the replacement carbs were not setup properly and I often wished for the old carbs back again, they just worked better!