tach problems and won't shut down

[kent1]

Hi guys,
My Dk35 which is now 6 years old developed a Tach problem about three years ago which didn't concern me a great deal but over the last two days it has developed the habit of not shuting down. Starts great but does not shut down by the ignition, I have to pull the choke out to kill the engine. Any thoughts on the tach or shut down problem would be greatly appreciated.
Thanks

 

[Willl]

I have to pull the choke out to kill the engine.

Choke ?

 

[ritcheyvs]

I have to pull the choke out to kill the engine. (

I'll assume you mean the manual fuel shutoff under the hood. You have one of two problems: either a wiring problem or the shutoff solenoid has failed. Some solenoids require power to keep the engine running and some get power only to shut the engine off (with a timer to remove power after a few seconds). I'm guessing you have the second type. The first step is to find the solenoid and hook a volt meter to the wires. Then see if it gets power either while running or after the engine is switched off. While you are in that vicinity, also look for a lose wire that got pulled off the tach sender. If the voltages look good, you have a solenoid problem but test it before replacing by running a jumper from battery + to the solenoid terminal. But if the voltages are bad (or the solenoid operates OK when jumpered from the battery) you have a wiring problem that will require troubleshooting with a meter and a schematic.

 

[VictorW]

If your tractor is six years old, about the time Kioti changed their shut down system, I believe yours may still have the shut off solenoid which is the type that uses a timer to energize the solenoid for about five seconds, after the key is turned off, to close the fuel to the injector pump. So power would not be found in the wire to the solenoid when it is running. You will only see the power in the wire to the solenoid just after the key is turned off for about five seconds. If it's the second type, you will have power to the solenoid constantly while the engine is running. ritcheyvs advised of these two systems. If you have the first type, check the solenoid as mentioned and if it works, it could be the timer relay on the firewall. If the solenoid is faulty and it's the second type, you have an easy fix.
As mentioned, the button you're pulling isn't a choke. Diesel engines use a fuel shut off to stop being that there are no spark plugs. You are simply shutting off the fuel supply. This button shouldn't be used as you would a choke on a gas engine.

 

[kent1]

Choke ?

Yea, I know it's called a fuel stop or something to that effect, it does not have the same effect as a gasoline engine "choke" but it is a choke. the difference is on a desiel it chokes of the fuel, on a gasoline engine it chokes of the oxygen. Think about it.

 

[kent1]

Thanks ritcheyvs,
Yea I know it's not called a choke but If you think about it is. desiel chokes of fuel, gasoline chokes of oxygen. I did not know that the solenoid could work there was solenoid I always assumed it just shut down power to an electric fuel pump of some sort. guess I will get out my meter and go look for the solenoid. Thanks for the rapid reply.

 

[kent1]

I've always called it a choke because it does the same as a gas engine except on desiel it kills the fuel supply, gas cuts the oxygen down. Thanks for the speedy reply. as I told ritcheyvs I didn't realize there was a solenoid that energized at any point. thought we were cutting power to an electric pump. now as i'm thinking of it in terms of a solenoid I believe it would be the type with the timer, if it were the other type it seems that it is constantly energized to keep the valve opened and if it failed the engine wouldn't start at all. am I correct in this assumption?
Thanks

 

[EE_Bota]

Yea, I know it's called a fuel stop or something to that effect, it does not have the same effect as a gasoline engine "choke" but it is a choke. the difference is on a desiel it chokes of the fuel, on a gasoline engine it chokes of the oxygen. Think about it.

I thought about it, per your request. I came to the conclusion that:

1) A fuel cutoff is not a choke in any way, shape or form.

2)Thinking of a gasoline engine's choke as a means to choke off oxygen is to nearly completely misunderstand what choking a gasoline engine does. It actually causes a shift from the venturi effect mode of creating of a pressure differential to instead using direct engine vacuum as the differential. One could completely remove the venturi, and the choking process would still introduce fuel.

 

[kent1]

I thought about it, per you request. I came to the conclusion that:

1) A fuel cutoff is not a choke in any way, shape or form.

2)Thinking of a gasoline engine's choke as a means to choke off oxygen is to nearly completely misunderstand what choking a gasoline engine does. It actually causes a shift from the venturi effect mode of creating of a pressure differential to instead using direct engine vacuum as the differential. Once could completely remove the venturi, and the choking process would still introduce fuel.

Okay, I can buy that in a totally technical aspect it would be true but to remove an ability to receive any element necessary to continue a given function can still be construed as "choking" according to the definition. In this sense it would be a choke and according to the technical difinition you've given me the choke on a gas engine is not truly a choke but a fuel/oxygen modification device. it truly isn't totaly choking off anything. We could debate this to infinity and I would enjoy it but...thanks for the i

 

[ritcheyvs]

Diesel 101. In most Diesel engines there is no restriction in the air going into the intake manifold (no choke and no throttle). In other words, the cylinders always get a full load of air. Power is controlled by regulating the amount of atomized fuel sprayed into the cylinders so the engine runs "lean" (extra air) at all but the highest power settings. To accomplish this, the fuel injection pump pumps a small metered amount of fuel to each injector and the injectors don't "pop" open until the fuel pressure reaches a predetermined value, typically above 2000 psi. The injection pump has a separate pumping piston for each engine cylinder and these are controlled by a "rack" that moves linearly to increase or decrease fuel to all of the engine's cylinders, simultaneously. The rack is controlled by the hand or foot "throttle" and a centrifugal governor so, in effect, your throttle position produces a fixed RPM so the injection pump increases or decreases the injected fuel quantity to maintain that RPM. Now, the final wrinkle is the fuel shutoff; the rack is moved to the full off position (zero fuel injected) by either the solenoid or the manual fuel shutoff lever. There is no provision to stop the engine by shutting off the air although people have done this manually (like a rubber bag over the air cleaner) to stop run-away engines.

All of the preceding applies to conventional mechanical injection systems. The new high-pressure electronic systems are different.