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1986 Dodge stalls when warm
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Les McGuinn
Anonymous Poster
lesmcguinn@yahoo.com
Feb 2, 2009, 2:02 PM
Post #1 of 10
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1986 Dodge stalls when warm
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Hello Everyone,
I have a 1986 Dodge Diplomat with a 318 cu. V8 that stalls as soon as the carb is warm enough to move off of the fast idle cam. As long as I keep giving good throttle it runs fine, but as soon as I let it go to idle it stalls. To restart I have to spray something like carb cleaner into the carb. I rebuilt top half of carb (wasn't confident enough to remove entire carb), replaced fuel filter twice, and replaced fuel pump.
This is a nice looking car with only 80,000 miles on her. Any advise would be greatly appreciated.
Thanks,
Les
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zmame
Veteran
/ Moderator
Feb 2, 2009, 2:45 PM
Post #2 of 10
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Re: 1986 Dodge stalls when warm
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Dose the choke open when it gets warm?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 2, 2009, 2:52 PM
Post #3 of 10
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Re: 1986 Dodge stalls when warm
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OK: Try to get it to stay idling on a middle step of cold fast idle cam and spray carb cleaner around all gaskets and things that could be vacuum leaks - CAUTION WITH THAT AS CARB CLEANER CAN FLASH TO FIRE! Pinch off suspect vacuum lines also as a check. If idle changes with the spray or piching or plugging off something that area has a problem.
Also: Low on front of carb should be two idle mixture screws. Even in 86 most were made "tamper proof" but they now are suspect of being dirty inside. If you can or know how to defeat the tamper proofing you would then need to screw in (may be and odd screw head - perhaps called 'cluch' head) and count turns in till they stop (gently to stop) as a reference to put them back exactly there! Roughly 3.5 turns from bottom out (counter clockwise) is a base setting.
Spray carb cleaner thru those with the screws out to try to clear them up. May not work. These engines get kinda hot under there and manifold and sludgy so you need to take them off to clean all that up with fine wire carb cleaner and just plain put a carb kit in it if you haven't,
T
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Les McGuinn
Anonymous Poster
lesmcguinn@yahoo.com
Feb 2, 2009, 3:19 PM
Post #4 of 10
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Re: 1986 Dodge stalls when warm
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Yes, when warm the choke is off. I found the left side idle screw with the funny head, but I could not see the right side screw on this holly 2bbl. Maybe I'll get a chance tomorrow to look some more.
Thanks,
Les
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 2, 2009, 3:37 PM
Post #5 of 10
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Re: 1986 Dodge stalls when warm
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There should be a fast idle screw separate from main idle which might not be a screw but some kind of diaphragm and push rod.
Generic pic shown - lighter color metal thing with a screw to it is the step cam for cold idle.
This is an outline of a somewhat common tamper resistant type screw used in some carbs - could be internal or external?? That's call "clutch head"
T
(This post was edited by Tom Greenleaf on Feb 2, 2009, 3:40 PM)
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Les McGuinn
Anonymous Poster
lesmcguinn@yahoo.com
Feb 2, 2009, 4:26 PM
Post #6 of 10
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Re: 1986 Dodge stalls when warm
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Yes I have a diaphragm and push rod. Is it possible that I have only one idle screw? It is too dark and late to work any more today so I'll check tomorrow.
Thanks for all the info,
Les
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Les McGuinn
Anonymous Poster
lesmcguinn@yahoo.com
Feb 3, 2009, 12:25 PM
Post #8 of 10
(5798 views)
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Re: 1986 Dodge stalls when warm
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Hello Tom,
I sprayed cleaner thru the idle jet. It seems to have helped a little. Then I watched carefully as the carb warmed up. The push rod does seem to be the primary idle. A tab on the throttle linkage makes contact with the push rod. Then for some reason the push rod retracts about 1/8 inch. At this time the engine starts to stall. Could the diaphragm be bad? It has two wires and a spring loaded screw on the rubber coated end cap.
Thanks again for all the help,
Les
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 3, 2009, 3:56 PM
Post #9 of 10
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Re: 1986 Dodge stalls when warm
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Some guesses that may help: A 318 should have TWO idle mixture screws to clean out. Now that you've told me a vacuum diaphragm and electrics control idle it helps me some. This could be slow to react vs all electric and a leak sure would confuse things.
Try removing the vacuum hose to the diaphragm, push it back by hand if possible and hold finger over vacuum port so see if it holds still - then let go and see if it moves out. Just a way to see if it seals. A hand pistol type vacuum pump is handy for this.
Some diaphragms do have intentional metered leaks so don't freak if it doesn't hold tight as I don't know this one specifically but items with metered leakdowns are at least slow about it. If instant it probably can't be much good.
Idle mixture screws: Note - they are there to mix fuel to a ratio best suited for idle and don't change the mixture of much more than idle and part throttle then that part of the carb isn't involved anymore. They still like to be clean and some require removal of carb to get real good and if horrible take fine wire, spray, compressed air and so forth to clear out. One could overcompensate for the other when TWO are used. They should be about the same # of turns out from stop +/- a 1/2 turn. Probably said it already - when all reference is lost use 3.5 turns out and that's frequently close. For exacting it when known clean you would lean (tighten) till idle speed just starts to drop and back off a tad 1/4 turn or so. These things can cover up problems elsewhere and shouldn't be doing that but rather fix why that cover up is needed.
Good luck. Again - a two barrel carb should have two idle speed screws. Most four barrel carbs still only use two as just two barrels run idle - not all that way but many,
T
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Guest
Anonymous Poster
lesmcguinn@yahoo.com
Feb 8, 2009, 1:58 PM
Post #10 of 10
(5774 views)
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Re: 1986 Dodge stalls when warm
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Hey Tom,
Eureka. I found the problem. Just posting here to say thanks again and to let you know the final resolution. I started on the problem again this morning and following your advise started searching this vacuum idle. Surprise to me it is all electronic, no vacuum. I'm old. What can I say. Decided to start all over again with diagnosis. Popped open the distributer cap. Rotor spring metal center conductor is all bent up and scored. Replaced cap and rotor and fine tuned carb idle adjustment. Looks like its gonna work. Pardon me as I now feel a need for humble pie.
Thanks,
Les
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