Guest Posted May 1, 2002 Share Posted May 1, 2002 What are the causes of engine run on? When you turn the key off the engine wants to keep running. Link to comment Share on other sites More sharing options...
wallaby Posted May 1, 2002 Share Posted May 1, 2002 Timing too advanced, idle speed too high, engine temp too hot. The three major causes for after-run. I have owned Chevrolets for years, and I just got in the habit of turning off the engine while it's still in gear. Link to comment Share on other sites More sharing options...
Guest Posted May 1, 2002 Share Posted May 1, 2002 What is the octane rateing of the gas you are using? You should be using 91 at least. If you are using a lower rateing, then your gas milage goes down which means that you are not saving money by using cheeper gas. This could also be another reason for the run-on. ------------------ George Lines Link to comment Share on other sites More sharing options...
Rob Peters Posted May 1, 2002 Share Posted May 1, 2002 This problem you are having is called dieseling. There is a solenoid on the left side (drivers side) of the carbarator. This solenoid has a bold head on it which the throttle linkage rests on. When the key is turned on and you press the accelerator to start the car the solenoid energizes (The bolt head moves toward the throttle linkage). I should say when the key is turned on the solenoid moves the bolt head toward the throttle linkage to be more accurate. You adjust this solenoid, I think by adjusting the bolt head or the position of the solenoid with the bolt head against the throttle linkage for the specified RPM, with the car in gear, when the solenoid is energized. This is the idle speed. You then leave the car running and disconnect the wire from this solenoid. When you disconnect the wire the solenoid should disengage and the RPM should drop. The problem comes in when the solenoid does not disengage from the throttle linkage to allow the rpm to drop when the key is turned off, thus supplying the car with fuel and if the engine is hot enough the fuel mixture can ignite in the cylinders just from the heat and compression, thus the term dieseling... If working properly this solenoid prevents the fuel from continuing by limiting the throttle position and allowing it to drop below the idle speed. Rob I hope this is not too confusing ------------------ Go Car or Show Car, it doesn't matter, you are welcome here Link to comment Share on other sites More sharing options...
Guest Posted May 1, 2002 Share Posted May 1, 2002 I'd try backing off the idel first. I run mine at around 850 to 900 RPM in gear. If it's a stock carb I'd probably drop that to around 750 RPM in gear. If that does'nt do the trick put reset the idel where it was and go back and retard the timing a few degrees. Jon. Link to comment Share on other sites More sharing options...
Guest Posted May 2, 2002 Share Posted May 2, 2002 You might want to look into some kind of aftermarket anti diesel valve. Of course unless you are very concerned about stock appearance. The anti diesel valve will drop the idle when the key is turned off. Link to comment Share on other sites More sharing options...
Guest Posted May 24, 2002 Share Posted May 24, 2002 Wallaby - Tell me about your answer and how it works. I don't get it, and haven't had the nerve to try it on my really tempremantal '70 filly. thanks! - Victoria/ mvreaser@aol.com Link to comment Share on other sites More sharing options...
Guest Posted May 24, 2002 Share Posted May 24, 2002 To be more specific and less dumb sounding, I understand how it works: it's in gear, ya turn it off. But, why doesn't this cause some gear/alternator/ engine nightmare that I can't even technically imagine ( which isn't too hard, actually) Thanks -V. Link to comment Share on other sites More sharing options...
wallaby Posted May 24, 2002 Share Posted May 24, 2002 while the trans is in park or neutral, the idle is rather high. When you put the car in drive, the engine slows down from the drag of the torque converter. Just turn it off while it's in gear, and the drag will help to stop the engine. Link to comment Share on other sites More sharing options...
Rob Peters Posted May 24, 2002 Share Posted May 24, 2002 If a car runs on there is a reason and it should be repaired. As I stated above, I would look into the solenoid on the drivers side of the carberator, I have seen these go bad and stick in the energized position. To test this solenoid is easy. It may just be a case of this solenoid being improperly adjusted. I just adjusted mine yesterday and I will try to give a fairly simple explination of how to test if it is working and how to adjust it. TO TEST THE SOLENOID: With the car running, locate the wire plug going to this solenoid. Unplug this wire from the solenoid and the rpm's should drop. To test it without the car running, just turn the key to the on position and unplug and plug in this wire on the solenoid, it should move the bolt head in the end of the solenoid toward and away from the throttle linkage. With the wire connected the solenoid will energize toward the linkage and with it disconnected it will move away from the linkage. If you have someone to help you just have them turn the key on and off without starting the car and the solenoid will energize and deenergize everytime it is turned on and off. TO ADJUST THIS SOLENOID DO THE FOLLOWING: In this adjusting you WILL NOT touch any of the carberator jet screws. The only tow things you will adjust is the Throttle linkage idle screw and the bolt head in the end of the solenoid which the throttle linkage rests on when the solenoid is energized. Now to adjust. Start the engine and bring it to normal operating temperature. With the car running, disconnect the solenoid plug wire. If the throttle linkage comes in contact with the bolt head while the solenoid is disconnected you will need to turn the bolt head in until it is nowhere near the throttle linkage. (you are going to do this so you can adjust the throttle linkage idle screw). If you have a tach meter, adjust the throttle linkage idle screw so the RPM's are about 400RPM's. If you don't have a Tach meter, adjust the throttle linkage idle screw until the car is near the engine stall point. Double check the throttle linkage is still not touching the bolt head in the end of the solenoid. If it is you will have to adjust the entire solenoid away from the linkage. Now reconnect the wire to the solenoid and adjust the bolt head in the end of the solenoid to a normal idle speed. On my car I have found that a nice idle speed is around 650 to 675RPM's. If I go much faster it jerks too much when you put it into gear and much lower than that may cause the car to stall when putting it into gear. I hope this helps someone in adjusting this solenoid. Many people are not aware of the purpose of this solenoid. Rob ------------------ Go Car or Show Car, it doesn't matter, you are welcome here Link to comment Share on other sites More sharing options...
wallaby Posted May 24, 2002 Share Posted May 24, 2002 Rob is correct. Engine after-run is a mechanical problem that should be fixed. It is a condition that can cause damage to your engine. If the after-run is severe, or persistent, then shutting it off in gear is only a "Band-Aid", and not the fix. Link to comment Share on other sites More sharing options...
Guest Posted May 25, 2002 Share Posted May 25, 2002 Off to Charlie, my mechanic and saviour with the whole solenoid detail printed in hand. Thanks, you guys. Sometimes, the easy way out is, well, the dumbest! Link to comment Share on other sites More sharing options...
MeanMonte Posted June 4, 2002 Share Posted June 4, 2002 An MSD ignition box will cause the engine to run on after u shut it off due to the low amount of power required to keep the ignition powered, This is corrected by putting a diode on the alternator light wire. i know this doesnt help but i thought i would through it out for anyone who might not know. Link to comment Share on other sites More sharing options...
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