carb issues with 1985 2.6L

[marty21711]

Hello, I have a 1985 New Yorker with a 2.6L carburated. Does anyone have good information on adjustments for this beast. It is a rebuilt. Five things it does. One is to fast cold idle. starts all the time though. Two is to slow of a warm idle feels almost like it is missing. I have new fuel filter , plugs , wires, cap, ect. Sometimes when I park in the drive way my wife says she smells gas, and usually you have to play with the pedal when cranking to start it. It is acting like it is flooded or out of gas. the last issues are worse. It has stalled during acceleration when warm, usually when I have gone from a parking lot to pulling out into traffic. the last seems to be more of a hiccup when I get up to speed about 30 to 50 mph and backing off the gas to maintain speed it fells like the engine is missing like very faint jerking. Aside from junking the 40k motor for a Mopar built 2.2, I would prefer to keep it. Thanks for any help

marty21711

[TomChrysler]

Hi Marty!

When has the Logic Module been replaced, if ever? The Logic Module controls all fuel feeds to the engine. It control idle speed, idle mixture, and other related functions. When it begins to fail. it will initially cough, sputter, and make your car run like it has bad gasoline. At first, it is intermittent. And within months (or less) becomes quite troublesome, and can do damage towards the end.

If it hasn't been replaced yet, I recommend replacing the Logic Module (inside of the front passenger kick-panel) as well as the Power Module (under the hood). Definitely cheaper than getting another engine (which would require a different Logic Module as well).

Giving you my best,

Tom

P.S. Check other postings on this site as other members (including myself) have gone through (or are going through) what you are now.

[marty21711]

I had a mechanic I trade work with look at the car and he found the first guy switched the mounting bolts front to back so the carb wasn't tight and was sucking air. He replaced the gasket switched the bolts. He also turned down the fast idle. I do not have the jerking problem when coasting as before, but I did stall pulling out into traffic today. Also sometimes starting it when warm you have to play with the pedal like its not getting gas or is flooded. Could this still be a logic module problem or a carb problem?

[85TurboAries]

im willing to test/repair any kcar ecu or logic module for $10 Plus shipping.
that includes a road test to verify performance

[TomChrysler]

Hi Marty!

Many auto parts storage have or can order them. I recommend Carquest Auto Parts. I have heard that other members have ordered them from NAPA Auto Parts.

Giving you my best,

Ton

[Alex's400]

Hello, I too have had some of the issues that are discribed by the original poster.
I have a 1983 Doge 400 convertible with the same Mitsubishi 2.6L and a carburetor.

Some of this was resolved by tuning the carb, returning the idle to the 800 rpm that is factory set and setting the timing at 7 degrees.

Now I am questioning the advice about the logic module, does a carbureted 2.6L even have a logic module??
Maybe this is the solution to the stumbling on acceleration that I have, I thought that the power valve was worn/poorly operating and that was it. I have heard that these are terrible carburetors and did not run well even when new.

Cheers
Alex

[PTT]

Check your carbs throttle shaft for play.

[terencejiminy]

Check your carbs throttle shaft for play.

RIGHT-ON!
Too many "Can't/Won't idle down" issues are mis diagnosed when the real culprit is the bore in the cartb base where the throttle shaft rides. VACUUM LEAK
There is a good chance the carb they rebuilt was worn worse than the core you turned in for it.
The inherant buzz vibrations of any 4cyl plays havoc, hammering the steel shaft in the aluminum base...
Good Luck
Terry

[Hemi-Dude]

Hello, I too have had some of the issues that are described by the original poster.
I have a 1983 Doge 400 convertible with the same Mitsubishi 2.6L and a carburetor.

Some of this was resolved by tuning the carb, returning the idle to the 800 rpm that is factory set and setting the timing at 7 degrees.

Now I am questioning the advice about the logic module, does a carbureted 2.6L even have a logic module??
Maybe this is the solution to the stumbling on acceleration that I have, I thought that the power valve was worn/poorly operating and that was it. I have heard that these are terrible carburetors and did not run well even when new.

Cheers
Alex

You got something there Alex. Here are a few problems and fixes for your Mikuni carb.
There was no logic or power module on an '83 or an 85 2.6L
Few 2.6L 'K' platform cars and 'S' body vans were built with a feedback fuel management system, but not until '86 when they appeared on the last year they installed the 2.6L in '87 models.
Fortunately, by then most were 2.2 TBI or Turbo and 2.5 TBI.
Then came the 3.0L which saved the day.
A major problem with the Mikuni carb in the years they were used on the 2.6L domestic cars and vans was a situation the 'Factory Guys' described as residual scaling breaking loose in the carb bowl from the fuel, or whatever it was.
This stuff would brake loose and partially block the low speed circuit causing stumbling as the throttle was opened slowly. If you punched it, the accelerator pump would provide enough fuel to overcome that but then when you leveled out on the throttle and drove with a light throttle, you would end up with what was a gentle surge or stumble.

The Holley/Webber carbs on the 2.2L were much more prone to throttle shaft wear than was the Mikuni. The Mikuni carb was a very well made carb compared to the cheaply built Holley/Webber. When working properly, the Mikuni was almost as good on driveability as the early fuel injection systems. Dealer mechanics were happy when all that went away and we all got fuel injection on everything. I guess you guys are too who have EFI.

The problem with idling down stems mostly from the choke circuit and the fast idle circuit. If the passageway through the carb is blocked (that's where the small rubber water hose enters at the top of the choke mechanism) there will not be enough hot water flow to heat the "Thermal Wax Unit" which pushed the throttle open for fast idle.
After all these years, I can imagine that many of you have the same problem. It was prevelant in the '90s.
Another large problem is the thermostat which must be a 195 degree unit and working properly.
BE CAREFUL, but if you start your engine cold and feel the upper radiator hose and the small hose to the choke, the one to the choke should get HOT long before the upper radiator hose.

I truly hope that this explanation will help many of you who still have a 2.6L Mitsubishi powered 'K' car or van.

Cheers to you too Alex