First thing Is EGR Valve doesn't affect the egine when given vacuum and Egr valve is good also i cleaned the passageways to the egr and it didn't do anything. My next thing to look at is the carb but im not sure what to look for any tips?
First thing Is EGR Valve doesn't affect the egine when given vacuum and Egr valve is good also i cleaned the passageways to the egr and it didn't do anything. My next thing to look at is the carb but im not sure what to look for any tips?
Welcome to the site. Have you removed and inspected the spark plugs? Checked compression? If compression is good then test for ignition, fuel/carb and emission issues. Does the truck still have the Mikuni carb? If so, don’t mess with it until you eliminate other potential causes of the idle and combustion problems.
Hello Andres and welcome :thumbup:
My truck is a California emissions 1986 2.6L 5 speed stick 4x4
The Mikuni carburetor was the cause of rough running but then I finally rebuilt it during the long covid pandemic shutdown...
Please check out my profile, photo albums & posts ~ maybe they will provide enough info for you to get your truck running well...
Many folks here will recommend swapping the Mikuni carb for a Weber carb but not me ~ it was enough of a challenge (and money) just to rebuild the Mikuni... I dunno but I really doubt that changing to any other carb or fuel injection system will be worth the hassle & money and the results won't be much different that what the Mitsubishi engineers designed into this vehicle...
I am happy with a rather CHEAP smooth running small truck that can keep up with traffic... If I was gonna invest hard earned money into a motor vehicle that is not really safe to drive fast or survive a violent collision then I would have to ask myself WHY AM I DOING THIS..? AFAIK these trucks don't even have crumple zones or air bags or anything else that could prevent death in a high speed crash..!?! The $600.00 to $1,200.00 to invest in a Weber carb will not result in any BUTT-O-METER results worth the trouble 'n effort 'n expense... But, I really dunno coz I never went that route...
Happy Holidays
George
I took it to a mechanic and he said the compression was fine and I checked the spark plugs and ignition that was good but yes it still has the Mikuni carb on it and the reason i think its the carb is i took it off like 3 or 4 times and was swapping in with a new Mikuni carb but now it has the old one and i mess up all the adjustments to the carb.
I never tried messing with the Mikuni carb adjustments but somewhere I have Chrysler publications about it... I think any & all diaphragm actuated devices on these older trucks should be considered trouble makers ~ every rubber diaphragm was cracked, rotten or pin holed on my truck ~ the Mikuni carb has several diaphragm operated devices & the distributor also has a diaphragm actuated vacuum advance part which can really negatively affect engine power...
Hope you have desire time money tools parts supply warm garage lifts helpful friends etc... to enjoy fixing your truck !
Never Give Up
:thumbup:
Check your ignition tune first - condition of the plugs and leads, plug gaps, advance on timing etc before messing with these carbs. Then wind out the throttle stop on the carb so the idle drops, check timing advance again. If the timing is too retarded and you use the throttle stop to adjust idle rpm, you are going down a rabbit hole. Get your hot idle right first. There are fast idle adjust screws on the throttle linkage. These need to be set when the engine is dead cold. The carb might only have clogged jets and purging them may help - run the engine with the air filter assembly off and cup your hand over the throats to starve it out. Sometimes the sudden increase of internal vacuum can free debris in the jets. There are a few main points of failure on the Mikuni Solex carb that are common.
Primary points of failure are (in guest appearance order):
- secondary throttle solenoid (diaphragm splits = no midrange to wide open throttle power)
- accelerator enrichment pump diaphragm (engine stumbles from off throttle to acceleration)
- auto choke (wax pellet type that uses recirculated engine coolant from the manifold - choke won't fully release)
- choke release assist diaphragm (doesn't appear to directly affect choke function, but causes an internal vacuum leak and messes with internal air metering when the diaphragm splits)
- fuel bowl vent solenoid (can cause dieselling/running on after the ignition had been shut off and general running issues)
- then there are vacuum lines - a LOT of them...
Bad diaphragms can be replaced without removing the carb but if they are already bad you will be better off either rebuilding the carb* or getting a good replacement.
*if you haven't rebuilt a carb before this is not the place to learn unless you are patient, thorough and have reasonable mechanical aptitude. The Mikuni is a complicated unit compared to something like a Weber... lose a metering float or a ball bearing inside the carb body and you will have a nice paperweight for your work bench.
If you can avoid using E10 fuel, do so. This stuff is crap and can damage plastic fuel filters, eat out fuel tanks and damage fuel level sender units and hoses etc.
http://www.mightyram50.net/vbulletin...and-do-it-ASAP
Check or change the fuel filter (pleats should be white or clean slight yellow tint)
Your truck is aged not young anymore regardless of miles on the odometer ~ father time ozone acid rain etc have taken their toll ~ some tests checks fixes parts replacement etc will be needed to make it run like new ~ if compression is good in all cylinders & valve and ignition timing are set correctly THEN AFAIK the distributor the carburetor or a plugged cat exhaust might be things to suspect and inspect...
Google ENGINE TROUBLESHOOTING CHARTS & CHECK OUT THE WIKI SECTION HERE
One J/Y Mikuni carb I used on my truck had a float that very slowly leaked (made a FLOODING CONDITION) which caused the truck to slowly loose power then die and never start again..! It was only by chance that I discovered fuel had leaked into the float ~ more like a miracle !!!
The rubber diaphragm in my truck's mechanical fuel pump caused engine power to steadily decrease to the point of troubleshooting causes for LACK OF POWER ~ replacing the fuel pump fixed the problem...
A new PCV valve greatly helped my truck idle nice 'n SMOOTH
If "smells bad" means a sulfur odor like rotten eggs, that would tend to indicate a bad catalytic converter, which could also explain the poor idle if the cat is partially plugged.
Agreed, after all the fixing of ignition carburetor new sensors I'm now searching to get a catalytic converter (when replacing the O2 sensor we saw the cat was 90% plugged..!) Truck exibits lack of power poor gas mileage rough idle black tailpipe and temp gauge gets to 3/4 scale on uphill grades ALL are symproms of plugged cat...Quote:
Originally Posted by SubGothius
25MPH stop & go driving here which will plug cats ~ gotta heat the cat on the H3 fwy to blow out the crud...