I own a 1987 Plymouth Horizon, 70, 000 miles on it. Long story short, The car sat for 3 years without being driven. It would just be started up whenever the other owners wanted to. I have fixed a lot of its problems, and replaced tires, brakes, hoses, belts etc… Problem I am having is when it
is started up it is at a very high idle and will not allow you to kick it down till it warms up or it idles down on it’s own after being warm. I have sprayed carburetor cleaner around the linkage and so on but it still does it. What could be causing it?
Like I said the car sat for 3 years and did have gas in it when I bought it and not being able to drain out the old gas I put HEET gas-line antifreeze & water remover in it. The fuel filter has been changed out twice. Once you get it on the road it runs like a champ for being 24 years old. It’s just the high idle when you first start it up. The owner of it had some little quirks I guess you would say. He had and they are still there, two clothes pens
on the gas rail/line and they were there because of vapor lock. They are located on two different parts of the line I guess to balance it out. Now I don’t know if this is true or how even remotely possible two clothes pens could have anything to help with vapor lock. Now I do know that on occasion it will run a bit and stop when you cut off the engine, though not all the time… Any help would be appreciated.
That car had a common problem with the gasket between the carburetor and the intake manifold breaking down. It’s a thick gasket, and as it deteriorated, it would allow air to be sucked in - often causing a raised/uneven idle.
I would check that out first.
Also, there is a high idle adjustment on this carb. Follow the linkage from the choke to the throttle linkage to find it. It may have been set abnormally high to keep from stalling cold with all the sitting it has done.
Also, the continued running is normally known as run-on, where the valves or the cylinders are hot enough to allow the gas charge to continue igniting without a spark from the plugs. A lot of carbs had an anti-run-on solenoid to cut fuel flow through the carb when the ignition was off. This may have been by-passed by the previous owner, sometimes because the solenoid would fail and prevent the car from running. I don’t know if this carburetor has one, but I’ve seen it done on old Toyota’s and Honda’s.
Thanks for the suggestions. It gives me something else to check out. Like I said before, the previous owner liked to take shortcuts to save a buck, but in the long run has cost me money because of that. Gaps were way off on the spark plugs, the air filter looked like it had never ever been changed, it was so filthy. I had never ever seen anything like that before. Parts were just hanging on by the bolt, with no nut attached to them at all.
Thanks again for the advise, will keep you posted on how the project goes…
Is this FUEL INJECTED or carbd? It could be injected at this year …No? Anywho if it is carbureted…it is your choke mechanism…The high idle may be set too high…its adjustable… Then you need to make sure the whole linkage system is working… You need to remove the air cleaner at the very least in order to see and diagnose all this… The auto choke is heat operated…does it work?
I could write on and on about how to do all of this…but that’s what repair manuals are for…
IF your car is fuel injected it could be as simple as having the cooling system properly filled up…with no air pockets in the system… THIS IS VERY IMPORTANT in a fuel injected car…
Go to Autozone dot com…they have the repair manuals there FOR FREE VIEWING…all you need to know is in there… I don’t feel like writing a book on here…sorry… But your issue is rather simple and you will find what you need in the repair manuals
Blackbird