I have a 1981 Datsun 210 90.8 CID that runs rough jist bought. Acording to the person I bought it from he had jist replaced spark plugs, wires, points, distrubitor, along with fly wheele, starter, altinator, and the motor had suposedly bheen rebult 2 years ago. I was warming it up when i reved it up to keep it from dying it sounded like the throttle got stuck iwould guess its stuck at 2000 rpm jist a rough guess. What should i do geting rid of it is not an option at this point in time its my only transport Please help
My first guess is that the carburetor’s secondary throttle plate is stuck open. This is usually caused by a buildup of gum or varnish on the secondary throttle shaft. The ideal repair would be to rebuild the carburetor, but generally it can be fixed by applying carburetor cleaner spray and penetrating oil to where the throttle shaft goes through the carburetor body and carefully working the throttle plate and/or throttle linkage (carefully because if either gets bent it could be a worse problem).
That would address the high revving idle, but probably not the rough running. There are many possible causes. A precise description of exactly how it runs (once the over-revving is fixed) might help us make some intelligent guesses.
Check and double check the firing order. With all the ignition components that were recently replaced, it would not suprise me to find two plug wires were swapped. I’ve found this done by a couple of working mechanics, and I have done it myself once when I thought I was being careful not to (I fixed it before driving the car). The correct firing order was on a sticker inside the hood when the car was new, it may still be there, otherwise get thee a chiltons or clymer book.
Fast idle may be any sort of vacuum leak, including via the power brake booster diaphram.
Gary, I don’t think she means it idles at high revs, but that the throttle linkage is actually stuck. Happened to me once in a '93 Accord (at speed), and I ended up having to pop it out of gear and pray the engine didn’t rev itself to death.
If I understand the OP correctly, all she needs to do is find that little throttle tab thingy under the hood and wiggle it to make sure it isn’t stuck.
what is a throttle tab thingy are you talking about the butter fly for the arb or the throttle linkige
carb sorryI just went through this with an 86 Honda Accord. Last of the carburetors. I’m not joking when I say this thing has about 20 vacuum lines and they end up going to a vacuum routing computer.
The short end of the story, the vacuum pull-down for the choke wasn’t doing it’s thing so I routed it direct to a vacuum source. End of rough/high idle. Car runs great.
Look at your choke linkage. chances are there is a vacuum operated device that pulls it open. Test it by applying vacuum to it.
Yes, I understood that. I used the phrase “high revving idle” to describe the symptom: engine running at ~2000 rpm while sitting still in neutral.
I believe it refers to part of the throttle linkage. If you’re lucky it’s something that simple.
The throttle plate I mentioned is also called a butterfly valve. The carb has two barrels, each with its own butterfly. The primary (1’) is operated directly by the accelerator pedal, connected to by a cable to a quadrant on the outside of the carb. The secondary (2’) is operated by a vacuum diaphragm, and is locked out from opening until the 1’ is most of the way open. Remove the air cleaner and look down into the carb with the engine off. If the 2’ butterfly is not shut all the way, it is physically stuck open, and what you need to do is work it free so it can go back to its rest (closed) position. It’s safer to apply force to its linkage arm than to the butterfly, which is thin and easily bent.
This problem occurs because under certain conditions the vacuum diaphragm can exert enough force to overcome the sticky shaft, but the return spring isn’t strong enough to bring it back. The clue here is that it happened suddenly when you revved the engine. Normally, if you hold the 1’ all the way open (as with the pedal floored), you can open the 2’ easily with a finger, and it will close when you let go. If it doesn’t, free it up until it does.
If that’s not the problem, go on to the other suggestions in this thread.
The part I’m talking about was something like a switch built into the throttle linkage, with insulated cable going out one side, and an exposed braided cable that looks a bit like a bicycle brake cable coming out the other; you can control the throttle with it from underneath the hood.
In the Honda it was way back, almost against the bulkhead.
OK TRIED IT AGAIN FROM COLD START NO HIGH REVS I LET IT WARM UP WITHOUT TOUCHING ACCERATOR AND IT REVED ITS SELF UP SO i PUT ON THE E BRAKE AND SHIFTED INTO REVERSE IT STOPED AND WAS RUNNING ROUGH LIKE ITS OUT OF TIME WHEN I SHIFTED INTO NUTRAL i HAD MY FOOT RESTING ABOVE THE THROTTLE AND NOTICED THE PEDAL MOVED A LITTLE NO FURTHER THAN 1/4 IF AN INCH SO i SHIFTED AROUND FOR A FEW AND THE HIGH IDLE WENT AWAY IN NUTRAL AND PARK WTF HAPENED
Still doesn’t hurt to double check the firing order. I have a Chilton and Haynes book for the same car with firing orders that disagree with each other. That was a frustrating hour.
Must… resist… urge… to correct spelling…
Can’t… hold it… much longer…
WHAT ARE YOU TALKING BOUT IT SEEMS QUITE REASONABLE U ARE BEING TOO JUDGMENTAL AND I THINK THAT YOU SHOULD LIGHTEN UP AND I THINK THAT YOU SHOULD JUST LET PPL ANNSWER THE QUESTION AND THAT IS THE POINT OF THIS MESSAGE BOARD AND MORE SUBSCIBERS MEANS MORE THINGS TO DISCUSS
Seriously, though, get thee to a Chilton’s. With all the work that’s been done, there are any number of tings that could have gone awry. Go back over the work with the book as your guide and you should be able to isolate any anomaly, or at least take notice of something that is outside tolerance.
I seriously doubt the high idle and rough running could be caused by mis-routed spark plug wires. Switching two out of four wires on a 4 cylinder engine is almost a guarantee of creaking a slug.
Think about it. You are losing 50% of the engine’s output.
I agree with a stuck throttle plate, or it could be a stuck choke, a bound up throttle linkage, or a carb that is running very rich, coupled with a vacuum leak.
The rough running could be a bad spark plug, part of the mixture problem, or an internal engine problem. Or one of about 1/2 a dozen other causes.
It will take a bit of diagnostic work to pinpoint the problem.