Lastec 3372 Kubota Engine Will Not Fire

[gene]

I have a Lastec 3372 mower with a 33 hp turbo charged Kubota D1105-T-ES engine. I haven't used it since November. It will crank, but will not fire. When I crank the engine it gets fuel at least to the fuel pump bleeder valve, but not to the injectors at the engine. It may be obvious, but does this mean that the problem is definitely a faulty fuel pump.
What's my next diagnostic step??????????

 

[Stumpy]

You've got fuel to the pump and you've tried bleeding at the injectors but don't get anything?

I'd check the stop solenoid and make sure it's not stuck and holding the fuel rack in the stop position.

 

[Eric McCarthy]

How fresh is the fuel? If its old it could be gunked up and causing a blockage.

 

[hodge]

You can get fuel to the pump but not enough pressure for the pump to function properly. Do the normal stuff like fuel filter, check the air filter, check for obstructions in the tank. Things can happen to diesel fuel that sits, especially if it has/gets moisture in it. If it ran in November, I would assume a fuel flow problem before a random injection pump/injector malfunction.

 

[gene]

All,
Yes, I get fuel to the pump, because it pulsates out the bleeder when I loosen it on the pump, but it does not get through to the injector fuel lines. I've disconnected them where they are connected to the injectors and get no fuel coming out of any of the three lines when I crank the engine.
The fuel in the tank was from last fall, when I last cut the grass. I then added new fuel, but did not drain the old. Is there anywhere in particular that the gunk is notorious for causing blockage.
Thanks to all for your advice and I'll let you know.
P.S. Stumpy, where is the stop solenoid usually located?

 

[Eric McCarthy]

Its a safe bet that if your getting fuel to the injectors but not out of them, then chances are the injectors are plugged up with gunk and crud. A jug of diesel fuel treatment might be the cure to break up and clean out the injectors. I believe Howse diesle treatment would work well, perhaps even Seafoam too.

 

[gene]

Eric,
Just checked on the fuel flow again. It's getting to the bleeder valve on the fuel pump, but is not getting from the pump to the injectors. I unscrewed the connector nuts holding the fuel lines to the injectors and then turned the engine over again. No fuel comes out of the lines, so the injectors are not receiving fuel from the fuel lines.
Gene

 

[Eric McCarthy]

HMMMM well I am out of ideas right now. Maybe the fuel pump has gone bad. Hopefully someone with more diesel experiance will chime in and help.

 

[gene]

Does anyone know if possibly a faulty fuel solenoid could be the culprit? And ... if so, how could I check the solenoid out to determine whether it's functioning properly or not?
Thanks

 

[Stumpy]

Before digging too deep I'd make sure you're actually not getting fuel out of the pump. Remove the injector lines from the top of the pump, set the throttle to full and crank it. You oughta get 3-4 inch geysers. If you do then it's probably just a matter of bleeding the lines. Put the lines back on, crack the lines at the injectors, remove the glow plugs, and crank til you get fuel at each injector.

If not then for chances are the fuel rack is stuck in the cut off position. It could be the stop solenoid is jammed or the rack itself could be bound up. I'm not familiar enough with that engine to give you specific instructions but on my engine there is a plate beneath the pump that'll let you see the rack.

If it shuts off with a key then you've got a stop solenoid. It'll be located on the back of the fuel pump or somewhere near by. I believe the idea is when the key is switched off the solenoid is energized by a timer for about 10 seconds which holds the fuel rack in the cut off position. I'd remove it and make sure it cycles with the key and that the piece it pushes on moves freely.

 

[gene]

Will do this today after I cut the lawn. Thanks Matt

 

[gene]

Here's an update. Took the injector stop solenoid off and it did not cycle when I cranked the engine. The prong stays in the extended position, but will depress with finger pressure. (The rack itself was not stuck and operated smoothly when depressed with my finger.) I left the solenoid disconnected and then took off the injector lines coming off the top of the injector pump. Cranked the engine and got the spirts of fuel indicating the pump was working. Blew out the injector lines and then reattached them back to the pump and cranked the engine and watched the fuel coming out of the disconnected injector lines at the individual injectors. Reconnected the stop solenoid; cranked the engine and no fuel came from the disconnected injector lines.
Does this means the stop solenoid is bad or maybe a bad relay to the stop solenoid?

 

[Stumpy]

If the solenoid stops the engine in the rest position then it works opposite the way I though in my previous post. It should be energized and retracted anytime the key is in the on position and when the key is switched off the solenoid deenergizes and it's spring holds the rack in the cut off position. From what I'm reading there should be two leads that power the solenoid. One is a lower amperage "hold" circuit for normal running, the other is a higher amperage "pull" circuit to make sure the solenoid stays retracted while cranking but would melt it if closed constantly.

If the run circuit was out it would try and start but die as soon as you let off the key. If the pull circuit was out it might behave like it has been except that the solenoid should be cycling with the key. I think the solenoid needs to be replaced but I'd make sure you're seeing voltage between each circuit and ground with a multimeter first.

No guarantees but that's how I read this.

 

[Stubbyie]

I'm leanding toward a bad 'stop' solenoid.

Try one more electrical test based on what your description above was: disconnect and remove the solenoid from its mounting. Leave the wires hooked up. Use a jumper from the solenoid metal mounting plate back to a known good chassis ground. Now try with the key. Check voltage on both 'input' wire(s) with key at 'on' and 'start'. Confirm good chassis ground both ends of jumper. If all wires confirm as they should be and solenoid doesn't work then bad and need new. May need a helper to do this. Personal preference would be to use an analog (needle type) voltmeter so you can "see" action instead of fluttering digits on screen.

Have been reports on here about leaving solenoid out of circuit permanently and using decompression pull-lever (if equipped) to kill engine. Think also there was one gentleman that rigged a string to the solenoid connection point and manually killed the engine by tugging the string. Think also there was one report of stopping by lugging the engine down to kill it.

Please post back and advise how resolved so we may all learn.

 

[gene]

Stumpy/Stubbyie,
Thanks for the suggestions. I'm sure I did not have the stop solenoid grounded when I had it wired, but out of its mounting location. (I know little to nothing about electricity, but do have a multimeter, so should be able to conduct the test tomorrow.) I did, however, look at the electrical schematic for the mower and noticed one wire from the solenoid (red/yellow wire) goes to a relay also. Just wanted to mention this for your information.
Bear with me on this project, and hopefully we can all learn from it.
Gene

 

[Stubbyie]

You may have a heck of a time trying to read voltage when the quick-connect wiring tabs are pushed down town tight onto the solenoid connectors.

Just to try getting a reading you can clip a straight pin or similar micro-probe in an alligator clip attached to your meter probe.

Another thing is to pick up at local parts house a few male and female 1/4-in (or whatever size you have) crimp-on connectors and make a set of super-short (or whatever length you need) jumpers to match your wiring hookup. You can skin a piece of the jumper wire that you can touch your meter probe to and then recover it with tape--instead of poking holes in or skinning your wiring harness insulation thereby creating future corrosion points.

Over time I've accumulated a coffee can full of different odds and ends jumper wiring parts. Sure comes in handy.

Don't be skittish of electrical troubleshooting. With a basic meter and patience you can learn more about your machine and repair most ekectrical problems. Wiring diagram is helpful too but most of these older non-computer systems are straightforward.

Let us all know what you find and how resolved.

 

[Apogee]

You might check for a blown fuse.

Also, I'd bet on a failed relay under the dash before a bad solenoid.

You can test the solenoid by applying 12v to the two wires on the solenoid. Make sure they are disconnected from the harness, and run power just to the two solenoid wires. It should suck in with voltage applied and spring back without any. If it works, then you know you need to look elsewhere.

If the solenoid only has one wire, then either make sure it's mounted to the block or attach the ground to the outside of the solenoid housing and positive to the single wire. Again, if it's working it will suck in with power and release without it.

I'd bet on a bad key switch, bad fuse or bad relay.

Hope this helps!

Steve

 

[gene]

Today I removed the stop solenoid from the injector pump and with the wires still connected to it, I grounded it while the ignition switch was in the on position; nothing happened with the solenoid prong. I turned the key to start and cranked the engine; again nothing happened to the prong on the stop solenoid.
I then removed the stop solenoid from it's two wire electrical connector and placed the solenoid aside and dealt solely with the electrical two wire connector. I took the multimeter in voltage mode and placed the positive probe in the #1 terminal slot in the wire connector and grounded the other probe while the key was in the on position. I got a reading of 12.28 volts with the ignition in the on position; and 9.24 volts with ignition in start position and engine cranking. I then did the same procedure with the #2 terminal slot in the wire connector. I received no voltage indication whatsoever in either the ignition on or start position.

 

[Stubbyie]

You need to track down a wiring diagram to figure out where both of the two wires to the solenoid are connected.

If two wires to the solenoid I bet one (the one you measured at 12+ volts with switch 'on', 9-v while 'start') supplies power to turn the solenoid "on" and the other (measured at zero in all cases) is the ground. Try tracking back that possible ground wire to termination. For that matter, confirm the 12-v wire is well connected and has a clean terminal both ends. Confirm both wires intact not broken kinked shorted.

The pulldown of voltage during 'start' now causes me to think about a weak battery and / or bad battery cable connections. Try jumping the battery from another vehicle or with a start-level booster hooked up. It might be that the power supplied to the solenoid during 'crank' is not sufficienct to 'open' the solenoid.

You may have two interrelated but different problems. Work on battery first and make sure you have strong strong battery and that all four ends of all battery cables are clean bright shiny tightly connected. Known problem is corrosion at chassis ground. Bad cables with internal unseen corrosion can create similar problem---look for green discoloration, broken wires, acid deposition, bulges. Lightweight smaller than required cable size can be a problem--okay perhaps when new but with any reduction for any reason fail to deliver sufficient power.

Confirm battery and general electrical power supply is good than go to solenoid. That way you know where to concentrate.

I'm still leaning toward bad solenoid. But even if replaced if you are getting low voltage to its terminal(s) you might have the same problem.

Mark which terminal on the solenoid is where you measured the 12-v signal. Just so you don't get crossed up. Then using your battery booster you can bench-test the solenoid completely apart from the machine and confirm function. You may need to make short jumpers for the booster clamps to grip.

There is some risk in this bench test unless you KNOW the second terminal is truly a ground by tracing back to its termination or confirming via wiring diagram.

Mark the suspected ground wire feeding the solenoid connection. Disconnect tractor battery. Use your meter set to 'continuity' or 'buzzer' and hold one probe on that suspected ground wire and the other probe to chassis ground. If you get a (or almost) full scale reading or the buzzer does then you confirm the ground. Then you can bench test the solenoid with a high level of certainty of which way the power flows and how it is wired to work.

Please post back and advise how this resolves so we may all learn.

 

[gene]

The two wires to the two stop solenoid terminals are as follows: The red with yellow stripe wire to the #2 terminal pulls the 12.28 volts and leads from the #2 terminal to one of three relays. The orange wire from the #1 terminal pulls no volts and leads to and ends as a blade connector to a white wire that goes to the starter solenoid.

I checked both wires for ground and the continuity checked out negative for both of them. (I guess this is obvious from what was stated in my previous paragraph, don't know.)

I checked all my battery terminal connections at both ends for each cable and they appeared clean, but I thoroughly cleaned them all.

I removed the stop solenoid from it's wiring and from its injection pump location to bench test it. I grounded it and then placed a jump wire from the positive battery post to #2 terminal. Nothing happened with the solenoid prong. I did the same to the #1 terminal and the solenoid kicked in and the prong was activated and moved in and out rapidly.

I'm going to trickle charge the battery tomorrow.