1990 3.9L stalls when comming to a stop
Registered User
Joined: Oct 2019
Posts: 2
Likes: 0
Same issue need help
Okay so I need hep. I hate to bump an old Forum but I have a 1990 Dakota 3.9 v6 and it has the same symptoms.
-rough idle
-stalling when coming to a stop
-no check engine light
I do have a vacuum line that I see is not plugged up, however I cant seem to find the place it actually connects to. I cant find a vacuum diagram ANYWHERE to save my life. I have been checking all other vacuum lines for signs of wear and possible leaks/clogs. I cant seem to find anything other than that line being disconnected. The truck runs fine once it passes 2k RPM's. I have noticed that there is also a metal pipe that runs to the original catalytic converter from around the passenger side header. This said pipe has rusted out and is no longer connected to the converter. I have held it up to the hole while the engine is running to see if there is any noticeable difference and I don't seem to see one except for the sound. It still keeps a rough idle. sometimes even stalls when sitting in park. PLEASE HELP!
-rough idle
-stalling when coming to a stop
-no check engine light
I do have a vacuum line that I see is not plugged up, however I cant seem to find the place it actually connects to. I cant find a vacuum diagram ANYWHERE to save my life. I have been checking all other vacuum lines for signs of wear and possible leaks/clogs. I cant seem to find anything other than that line being disconnected. The truck runs fine once it passes 2k RPM's. I have noticed that there is also a metal pipe that runs to the original catalytic converter from around the passenger side header. This said pipe has rusted out and is no longer connected to the converter. I have held it up to the hole while the engine is running to see if there is any noticeable difference and I don't seem to see one except for the sound. It still keeps a rough idle. sometimes even stalls when sitting in park. PLEASE HELP!
Grand Champion
Joined: May 2019
Posts: 5,156
Likes: 723
From: S.W. Indiana
Okay so I need hep. I hate to bump an old Forum but I have a 1990 Dakota 3.9 v6 and it has the same symptoms.
-rough idle
-stalling when coming to a stop
-no check engine light
I do have a vacuum line that I see is not plugged up, however I cant seem to find the place it actually connects to. I cant find a vacuum diagram ANYWHERE to save my life. I have been checking all other vacuum lines for signs of wear and possible leaks/clogs. I cant seem to find anything other than that line being disconnected. The truck runs fine once it passes 2k RPM's. I have noticed that there is also a metal pipe that runs to the original catalytic converter from around the passenger side header. This said pipe has rusted out and is no longer connected to the converter. I have held it up to the hole while the engine is running to see if there is any noticeable difference and I don't seem to see one except for the sound. It still keeps a rough idle. sometimes even stalls when sitting in park. PLEASE HELP!
-rough idle
-stalling when coming to a stop
-no check engine light
I do have a vacuum line that I see is not plugged up, however I cant seem to find the place it actually connects to. I cant find a vacuum diagram ANYWHERE to save my life. I have been checking all other vacuum lines for signs of wear and possible leaks/clogs. I cant seem to find anything other than that line being disconnected. The truck runs fine once it passes 2k RPM's. I have noticed that there is also a metal pipe that runs to the original catalytic converter from around the passenger side header. This said pipe has rusted out and is no longer connected to the converter. I have held it up to the hole while the engine is running to see if there is any noticeable difference and I don't seem to see one except for the sound. It still keeps a rough idle. sometimes even stalls when sitting in park. PLEASE HELP!
You have a pre-magnum engine but try cleaning your throttle plate on the throttle body. Use throttle body cleaner NOT carburetor cleaner and use a paper towel to rub around it and clean the gooky stuff (<---fancy technical term) out. It will run really bad once you get done but it may clear the problem up.
Registered User
Joined: Oct 2019
Posts: 2
Likes: 0
update
I noticed that the brake booster had a vacuum line that was capped off. The cap looked to be as if it didnt give a good seal. I readjusted this cap. I took the fuel injectors out and cleaned them. They were dripping gas, I dont know if this is good or bad? I noticed someone may have changed the injectors before me, however they didn't have them seated all the way. I properly seated the injectors. I then noticed that the bolt coming off the idle air control valve controlling the plate to the throttle body was loose. I tightened this bolt. The truck is running fine now, idles about 700-800 and no more hesitation when giving gas. Still no check engine light and no codes. Battery did die recently so I will drive around and let you know if anything changes.
Grand Champion
Joined: May 2019
Posts: 5,156
Likes: 723
From: S.W. Indiana
I noticed that the brake booster had a vacuum line that was capped off. The cap looked to be as if it didnt give a good seal. I readjusted this cap. I took the fuel injectors out and cleaned them. They were dripping gas, I dont know if this is good or bad? I noticed someone may have changed the injectors before me, however they didn't have them seated all the way. I properly seated the injectors. I then noticed that the bolt coming off the idle air control valve controlling the plate to the throttle body was loose. I tightened this bolt. The truck is running fine now, idles about 700-800 and no more hesitation when giving gas. Still no check engine light and no codes. Battery did die recently so I will drive around and let you know if anything changes.
Change your oil and filter as soon as possible. Leaky injectors can dilute the oil with gas and shorten the engine life.
Registered User
Joined: Feb 2024
Posts: 1
Likes: 0
my 1990 dodge dakota is sitting around 170k miles and runs perfect down the road. The problem of it stalling only happen when I am comming to a stop, some times it will idle rough, act as if it is going to die then surge to regain idle... or sometimes it just plain out dies. Im pretty much posting because ive exhausted a lot of my money and time trying to figure out what the problem could be. I have had it to 2 diffrent shops and the dealership look into it but no one knows whats wrong(altho they all charge me). This is a list of services and parts i have had replaced, If anyone out there has any reccomendations on what the problem could be I would be much appreciative.
Replaced--
Main computer
idle speed control motor
exhaust system
O2 sensor
distibutor cap & wires
Ignition coil
fuel injector(x2)
Air filter
tested by dealership--
EGR valve
fuel pump
As you can see ive gone through a number of options and im die'n to find someone, anyone that knows this make of truck well enough to maybe gone through or found this problem out before.
tx in advance,
Mifune.
Replaced--
Main computer
idle speed control motor
exhaust system
O2 sensor
distibutor cap & wires
Ignition coil
fuel injector(x2)
Air filter
tested by dealership--
EGR valve
fuel pump
As you can see ive gone through a number of options and im die'n to find someone, anyone that knows this make of truck well enough to maybe gone through or found this problem out before.
tx in advance,
Mifune.
