Yanmar starting problem

[Land-Tech]

I have a Mustang 2040 that has a Yanmar 4TNE84 diesel that started to have problems last fall. All of the sudden it quit starting on it's own. One shot of starting fluid and it would start up every time and run great.I used it a few times and then parked it for the winter.But even warmed up it wouldn't start. A small shot of fluid and away she would go.This motor has been great starting in the past .I drained fuel tank, changed filters, and put all new fuel with appropiate additives.
I replaced the fuel selenoid about 3500 hrs ago and didn't notice anything until about 50 hrs ago. I can't find the electrical schematic that I have, but I remember the selenoid had a three pin connector. I know that the fuel is on after it fires because it runs so it must be energized.
Is there anyone that has experience with Yanmar with similar symptoms, and might know what the extra wire is for. I seem to remember that when you turn the key all the way to start, two were energized and when you let off the key to run position only one was hot. The selenoid might be bad again or at least half bad I think might be a double acting and the shaft might extend futher when both are energized and I am more curious as to why this would be.Most small diesels I've been around have had simple fuel shut-off. scott

 

[Tazza]

I would start by changing your glow plugs, thats most likely your problem.
The solenoid, it has 3 wires? One will be earth, one will be hold, one will be pull. The pull coil pulls the solenoid in, it has a very high current draw, thats why it gets hot. When the plunger is all the way down the low amperage hold coil holds the plunger in place. When power is shut off, the plunger releases and the engine stops.
From what you say that the engine starts with a snort of ether this means your shut down solenoid is not the problem as if it was, it would not run, even with the ether. Check the plugs, or at least make sure you have power at the plugs.

 

[Butters]

I would start by changing your glow plugs, thats most likely your problem.
The solenoid, it has 3 wires? One will be earth, one will be hold, one will be pull. The pull coil pulls the solenoid in, it has a very high current draw, thats why it gets hot. When the plunger is all the way down the low amperage hold coil holds the plunger in place. When power is shut off, the plunger releases and the engine stops.
From what you say that the engine starts with a snort of ether this means your shut down solenoid is not the problem as if it was, it would not run, even with the ether. Check the plugs, or at least make sure you have power at the plugs.

Could you fuel pump timing be off? I am not famaliar with Yanmar, but most diesels I know of don't like to start with a pump slightly out of time.

 

[Land-Tech]

Could you fuel pump timing be off? I am not famaliar with Yanmar, but most diesels I know of don't like to start with a pump slightly out of time.

timing might be invoved here but I don't think the pump is off and it is gear driven. the machine runs really well after it starts. The paint is good at the flange so I don't think it moved.
I went out this morning and checked the wiring harness, it has three wires,wht ,red and blk. I assume that the wht is earth and the other energize. I think that the solenoid is a dual coil some thing like you have on hydraulic systems with solenoid controls. When I turn the key to the run position, this turns on the fuel by extending the rod into the governor linkage,and when I turn the key further it moves the rod even further out.when you cut off power, a internal spring in the solenoid moves the rod back to shut off fuel. The thought I had after I read Butters input is maybe it moves the inkage to advancr the timing and maybe centrifical weights take over after it starts. That little boost from the ether gives it a kick that the starter won't. Also until I check for current in the harness I haven't eliminated the key switch.
I'm just guessing so I'm going to pull solenoid today and check for current in the harness. thanks scott

 

[Land-Tech]

I would start by changing your glow plugs, thats most likely your problem.
The solenoid, it has 3 wires? One will be earth, one will be hold, one will be pull. The pull coil pulls the solenoid in, it has a very high current draw, thats why it gets hot. When the plunger is all the way down the low amperage hold coil holds the plunger in place. When power is shut off, the plunger releases and the engine stops.
From what you say that the engine starts with a snort of ether this means your shut down solenoid is not the problem as if it was, it would not run, even with the ether. Check the plugs, or at least make sure you have power at the plugs.

Tazza ,thanks for the input, I checked the glow plugs and they are ok. this thing won't start warm or cold and I seldom used the pre heat when it was warm. the starter and battery are less than year old.
With a solenoid on a Kubota does it shut off air along with fuel ? How does the solenoid act ually work after it pushes the linkage. thanks scott

 

[Tazza]

Tazza ,thanks for the input, I checked the glow plugs and they are ok. this thing won't start warm or cold and I seldom used the pre heat when it was warm. the starter and battery are less than year old.
With a solenoid on a Kubota does it shut off air along with fuel ? How does the solenoid act ually work after it pushes the linkage. thanks scott

It only shuts the fuel off, not the air.
Simply put, when you turn the key to the "on" position the hold coil is energized. The hold coil does not have the power to pull the plunger down though, its ONLY used to hold the plunger when it has been pulled all the way down by the pull coil. Then you turn the key further to the start position the pull coil pulls the plunger all the way back, this is usually wired to your starter so when you stop cranking power to the pull coil stops to prevent the coil burning up. When you let the key go, the hold coil will hold the plunger in place till you turn the key off. The plunger will let go and your fuel will shut off stopping the engine.
The hold coil draws only a few watts but the pull coil draws about 100 watts or more. Its not designed to run all the time or it will burn up. Its only run for a short time thats why they usually wire them into your starter. You only crank for a few seconds, not too long to damage the coil. I think they can be run for up to 60 seconds before you risk damage.
I would get someone to sit in the seat and turn the key to try and start it while you watch the stop lever. Make sure it pulls back and when they stop cranking that the arm start in position. Get them to turn the key off and make sure the arm swings back to the stop position.
Clear as mud?

 

[Land-Tech]

It only shuts the fuel off, not the air.
Simply put, when you turn the key to the "on" position the hold coil is energized. The hold coil does not have the power to pull the plunger down though, its ONLY used to hold the plunger when it has been pulled all the way down by the pull coil. Then you turn the key further to the start position the pull coil pulls the plunger all the way back, this is usually wired to your starter so when you stop cranking power to the pull coil stops to prevent the coil burning up. When you let the key go, the hold coil will hold the plunger in place till you turn the key off. The plunger will let go and your fuel will shut off stopping the engine.
The hold coil draws only a few watts but the pull coil draws about 100 watts or more. Its not designed to run all the time or it will burn up. Its only run for a short time thats why they usually wire them into your starter. You only crank for a few seconds, not too long to damage the coil. I think they can be run for up to 60 seconds before you risk damage.
I would get someone to sit in the seat and turn the key to try and start it while you watch the stop lever. Make sure it pulls back and when they stop cranking that the arm start in position. Get them to turn the key off and make sure the arm swings back to the stop position.
Clear as mud?

I see what you are saying. I tested the wires and found that when the key was in the run position red wire stays on, when you turn to the starting position wht wire stays hot until you switch back to run and then it goes off. I can't see the actual shaft move as it's inside the housing. The Kubota is exposed which is nice for a visual check. My connector to the solenoid has bare wires on the ignition side and was twisted and I think they might have shorted ans burned up the solenoid, I have to pull and find out. This machine does have a control module but I don't want to confuse the issue any more than I have. when I double checked against the Kubota, it has same wiring. red stays on the run position , wht stays on only for a second and shuts off whether turn the key back to run or not. Hook up the connector and it fires right up. Thanks for your patience Tazza and I will let you know how it goes. Also should I edit my wild ideas or leave in previous post? scott

 

[skidsteer.ca]

I see what you are saying. I tested the wires and found that when the key was in the run position red wire stays on, when you turn to the starting position wht wire stays hot until you switch back to run and then it goes off. I can't see the actual shaft move as it's inside the housing. The Kubota is exposed which is nice for a visual check. My connector to the solenoid has bare wires on the ignition side and was twisted and I think they might have shorted ans burned up the solenoid, I have to pull and find out. This machine does have a control module but I don't want to confuse the issue any more than I have. when I double checked against the Kubota, it has same wiring. red stays on the run position , wht stays on only for a second and shuts off whether turn the key back to run or not. Hook up the connector and it fires right up. Thanks for your patience Tazza and I will let you know how it goes. Also should I edit my wild ideas or leave in previous post? scott

If you have time please edit the mis information out. It just makes it easier for the next guy to get to the bottom of his troubles.
Ken

 

[Land-Tech]

If you have time please edit the mis information out. It just makes it easier for the next guy to get to the bottom of his troubles.
Ken

I pulled the selinoid and checked it and it was ok. So I went back to the basics. checked fuel lines,fiter and lift pump. lift pump was weak so I bypassed with electric pump and what do ya know, it started right up. I assumed the thing would not run at all with out lift pump but I guess it will. The short kick it got from the fluid got it pumping enough to run, I put quite a few hrs on it in this condition and you would think with a weak pump I would notice a loss in power.
I should have known this cause all the 7.3 diesels (i have 3) needed a electric pump to take care of priming problem they have.But when the lift pump starts to go in those, they start hard and you notice a definite power loss.
After spending a lot of time searching on the net for this particular engine (4tne84), I found that quite a few manafactures have used them. Deere in there tractors,I don't know about their skids, and some can be found in mini-excavators of various types. Scott