Case 450ct engine cutting and not restarting

I have a buddy who owns and lets me use his Case 450 CT skid steer. Over the last several months it has been behaving in an odd manner and I was hoping someone could point us in a direction to diagnose and hopefully fix the problem.

When it is running, the thing runs perfectly. It will randomly just stop running, no sputtering or warning, just stop as if you turned it off. From that moment till usually a couple of hours later, any attempts to start it will be a clean turn over that sounds great but does not catch in the least and definitely doesn't start back up.

If you let it sit for a few hours it will then randomly start perfectly. As in doesn't even require a full turn over before it is running beautifully. It will then run for a half hour to an hour and then just randomly stop running again.

During the down time when it will not start, it has plenty of juice but will not start even with full battery or on a booster/trickle charger. It also does not spew anything at all from the exhaust stack when it is being turned over. It seems like the fuel just stops flowing and then turns back on randomly.

But as soon as it decides to start again it doesn't hesitate. It's after midnight here right now, but will get a hold of my buddy in the AM to see what all he has tried to do to fix it.

I was hoping someone could point me towards some diagnostic algorithms or potentially have some good ideas of where to start looking.

Any and all help is appreciated. Figuring this out would definitely score me some points with my buddy who is kind enough to let me use this thing from time to time.

Welcome to HEF @AKNewb
Could be as simple as fuel tank breather being blocked.
Next time it stops, remove the cap & listen for any vacuum. Try to start with the cap off...... you never know.....

.....delete.....

alrman said:

Welcome to HEF @AKNewb
Could be as simple as fuel tank breather being blocked.
Next time it stops, remove the cap & listen for any vacuum. Try to start with the cap off...... you never know.....

Click to expand...

Thank you for the reply sir. I will try that in a few hours once I’m off duty.

Another thing we gotta determine is>> Is the inj. pump pumping fuel TO the injectors.??
1st diagnostic is to "loosen the fuel cap" as stated above.. & try starting..
2nd would be to loosen a few lines AT THE INJECTORS & SEE if they are squirting fuel.. {yes or no}
3rd, MAKE SURE your getting voltage TO the shut-off solenoid on the back of the inj. pump..
a simple test lite or multi-meter/volt meter.. should have 12v while cranking.. some send voltage w/ the key in the "on" position.. some require the engine to be spinning..
It could be something as simple as>>u have a shut-off solenoid breaking down & wont start back till its cool.??

Fuel shutoff relay could be the culprit also. Like thepumpguy said check voltage at solenoid when you first crank it and after it dies.

I have seen where the fuel shut off wire and the timing advance solenoid wires get mixed up.
Timing advance gets power through a temperature switch when the engine is cold, when the engine heats up the temp switch cuts off power................ When the engine cools again, the temp switch sends power through again.
I'm sure you can see how this would act if the timing advance wire was on your fuel shut off.

Timing advance is circled in green (wire should go to temp switch)
Fuel shut off circled in red. (wire should go into harness)

Follow thepumpguysc post too.
Fuel shut off solenoid should have power at key on.

Thank you for the replies. I was looking at the wiring harness and then the wire coming off the fuel shut off solenoid. Am I putting my test Meter probe on the wire coming of the solenoid or does the wiring harness have to be accessed?

Is the line coming off the solenoid a grounding conductor or am I missing another wire. I’ve seen solenoids with two wires but I haven’t tested one set up like this one.

Thanks again.

I should state that I could be missing something in what I’m seeing. I don’t have the arms up and it won’t start so I’m coming from a crappy angle to see the wiring.

Put your meter ON the solenoid.. its a 1 wire solenoid & grounds thru the body of the solenoid.

Copy that! Have had two cycles of starting and not starting to test. It shows zero volts when it won’t start and 12 volts when it will start.

I’m assuming that means the next step is replacing the fuel stop solenoid? Or does it mean it isn’t getting power so it’s something else?

I can’t thank you enough for your help.

The wire is FEEDING IT voltage.. so if your NOT getting power, then its from something else.
That wire is pretty thin.. u might be able to trace it & look for a break..
I think it get s its power from the key switch.. Ur gonna need a wiring diagram..
Try hot wireing it & see if it starts EVERYTIME..

Thank you very much for the reply and information. As you indicated I am following power back and have found power to be all or nothing at the solenoid. No abrasions/cuts found on what I could see of the wiring running back.

I am testing the relay currently and find it to be good, both through resistance testing and swapping it out with a known good relay. Both swapped relays behaved as if they are both good and the problem is with the power supply to the relay.

I am now testing the power coming into the relay using the female leads that receive the relay prongs.

I had tested another relay dock, the accessory relay when I knew it was powered and working properly. I found that two of the receiving clips had power coming in and both were the same at 12.65v.

When I test the fuel shut off relay (when the machine will not start) I am getting 12.65v on the one point but only 11.15v on the other. I’m assuming this is why the relay isn’t clicking. Shouldn’t they be the same?

Once it decides it wants to run again I will test those same leads.

Does this indicate a draw prior to the relay station? Or maybe in the dock itself?

Thank you for any input.

The voltage is a little different than my post above because I just took these pictures.

Ok. It will start right now. The relay is clicking when the ignition is turned on. With the engine off (but capable of starting this time) the relay dock/connectors show the following on the meter.

12.7v on one and 12.23v on the one that read low when it wouldn’t start.

Still a difference in voltage but the 2nd lead is giving at least 12v. Is that why it’s working?

Thoughts?

I plugged it in to a smart trickle charger so the overall voltage is increasing.

Do u have 1 or 2 solenoids on your inj. pump.?? RE-read post #7..
U may have a bad connection UNDER the fuse/relay block.?? or maybe the wires are loose & not making a good connection.??
Have u ran a constant HOT to the solenoid yet.. straight from the battery to the sol. & see if it starts every time..
Is there a "timer relay" in that system.. ?? did u get a wiring diagram yet.?? Its awful hard to diagnose if u don't know what the legs are SUPPOSED TO read..

Thank you again for the input.

- I am hunting for a wiring diagram. I'm going to end up buying one of the downloads but was trying to find one open source somewhere.
- 1 fuel shut off Solenoid on the inj pump in addition to the timing advance.
- The wires from the timing advance and the fuel shut off solenoids are not mixed up.
- It seems to very clearly start up when there is at least 12 volts coming in to the fuel shut off relay and not start when there is less than 12 volts coming into the relay.
- I will evaluate the dock and wiring underneath it when I get home day after tomorrow as well as follow up on your other points.

Thanks again.

The wiring diagram shows the safety lockout systems between the ignition and the relay as it sounds like is no surprise to you guys.

The relay dock (alligator clip type) had two leads that were very loose from the clip to the prong. Tightened those up and it seems to run fine for about 2 hours (longer than it had run before) but now it's stalling again. So that may have been something or it may have been a fluke.

When the rig will start, it starts without the seat sensor or safety bar sensor being activated so I don't think they would cause it to just shut down would they? I need to look harder at the wiring diagram and see what specific lockouts would shut down the engine.

Thanks for the feedback.