[J. Baker]

When it dies, you have to verify if it lost spark, or fuel.

My bet is either losing fuel, or something in the OPS system is malfunctioning. The latter is easy to test.

 

[J. Baker]

Yes, that is it. How do you verify if it lost spark or fuel when it is not running, and it starts again right away?
Pardon my ignorance. What is OPS?
Thanks

OPS= Operator Presence System

When it dies, don't try and start it. See if you can get the plug out of the bottom of the carb before restarting. If fuel runs out, it likely isn't running out of fuel, so it must then be losing spark.
Disconnect the engine kill wire from the machine after starting. Go run it. If it still dies, then you have a problem within the engine. If it doesn't it's an OPS problem or a short somewhere within the kill system. Remember, you may need to power the fuel cut off solenoid from another source as it may also be tied into your OPS system. Some are, most are not. Eliminate what it isn't, and you will find what it is.

I'm going to suggest you find a shop to take it to. It doesn't seem you know much about these systems and how they work. You really need a manual for both the engine and the machine with wiring diagrams so you can see how the two systems are tied together. Guessing isn't diagnosing.

 

[J. Baker]

Might be the choke linkage closes good, but it doesn't open completely...
Then it will start fine, and as soon as it warms up it loses power.
If a linkage is loose often the choke can be adjusted enough to still close...
But once you get moving the play in the linkage allows for play in the choke valve, and that play allows the plate to close even partially it cuts the air flow and thus power.



On the metal ones, inside the hole where the linkage hooks to the carburetor there is a hard plastic grommet piece or there should be... That was the problem I had, the little hard plastic grommet inside that hole was cracked and allowing linkage play. It was so minor, took me literally years to track it down.

I did the same as you, both coils, valves, fuel lines and filter, cleaned up underneath the covers real good... I was at wits end. I took it to a repair shop twice and it didn't act up when I was there, not even driving it around and engaging the blades but take it out to mow for a day and I couldn't even finish the first yard.
I replaced gas caps too, thinking if a gas cap vent was clogged.

When I replaced the carburetor...
Which at this stage I was just replacing parts, but it came with the new plastic pieces.
That's when I saw the problem.

Linkages on these things...

Here's the old thread on that FH721V:

FH721V suddenly started struggling

On my ztr today... I adjusted the valves about 1-2 years ago... It ran good for quite a while, but today while going up an incline it suddenly lost power. It will run "all right" without load but it does pop and sputter a little. Engage the blades and it pops and misses just a little more...

www.lawnsite.com

It would start awesome, run good for a few minutes and then the nonsense would start...

And none of that would cause it to die suddenly as if the key was turned off.

 

[J. Baker]

BTW I have the service manual for the kawasaki and the mower. They do not have troubleshooting steps that help in my case.
Thanks.

No I don't imagine that they do. Most books don't. But they do have wiring diagrams, or should. A book doesn't usually tell you how to diagnose a problems, they give you the information you need to be able to fix a problem, or references that help you to diagnose.

 

[J. Baker]

Does it die with PTO on or off

That's a really good question to ask!
Two different paths for the OPS system depending on if it is on or off. Also, if it does it with it both on and off, that will eliminate a lot of possibilities.

 

[J. Baker]

I think it is something internal with the engine that when it warms up it looses all the power. I wander if a warped head will do that."

No.
Well, it could I suppose, but highly likely. And not within a minutes time, and not without being very noisy. Usually if a head is warped that bad and leaking you can hear it.

I think you’re chasing your tail.

 

[J. Baker]

Yeap.

“Yeap”?
Are you agreeing that it isn’t a head?
Or that you’re chasing your tail?

 

[J. Baker]

Yea, been there done that when it comes to electrical problems...I have been burned with what I thought was a good battery. At a minimum, I would do a draw down test.......Free at most auto parts store if you don't have the tool.
.

I’ve had that happen once on a Chevy Blazer 20 years ago. Battery dead shorted inside suddenly. Had 12.? Volts on it but wouldn’t start the car. Changed the starter and cables. Didn’t fix it. Put the charger on it just to bring it to full charge and the battery got HOT. That’s when I found it. Glad it didn’t blow up when I charged it.

 

[J. Baker]

I changed the carburetor, I robbed the old engine which ran great, it is not new.
Thanks

Did you use a new gasket?

If you start the engine and let it just sit and run at half throttle but don’t drive it, will it die just sitting there running?

Edit: I see now you said earlier it doesn’t die until loaded, but I’m still curious to know if it will run at mid to full throttle not under load indefinitely?

Also, simply engaging the PTO kills it?

We may need a video to help you further.

 

[J. Baker]

I had checked spark before and have spark on both cylinders, but I don't know if a coil that is failing can recover that quickly.

It cannot.

 

[J. Baker]

Good to know.
The wiring diagram shows the oil pressure sensor is connected to the carburetor fuel solenoid at the key switch. Could it be telling me that I have low oil pressure?

Does the machine have an oil pressure light?
I doubt it has a SENTRY system. Very few machines do.
I think you are misinterpreting the wiring diagram.

Mr. Mouse will lead you on a wild goose chase worse than you’re already on. Be warned.

 

[J. Baker]

You need to be more methodical, and stop skipping all over the place.
You need to complete some tests you were asked to complete and report back. Such as if disconnecting the engine controls (kill wire) from the machine eliminates the problem.

 

[J. Baker]

Yes, the machine has an oil pressure light.
I am not misinterpreting anything.
You look at the diagram.

Yes, you certainly are misinterpreting the diagram. The diagram shows exactly what I expected it to.

That shows that both the carb solenoid and oil pressure light both receive power from the same terminal of the ignition switch. They are not connected in ANY way. Only share the same power terminal. The oil pressure switch provides ground path to turn on the light if oil pressure is lost.

 

[J. Baker]

Yeap, that is my next test.
I got a little excited there.
Answer me this:
Is the oil pressure sensor (basically a switch) normally on or off?
Thanks

Forget the oil pressure switch. It only runs the light. It’s not related to anything.

 

[J. Baker]

Baker, basic electrical wiring tells you that if two wires share the same terminal THEY ARE CONNECTED.
So is the ground path from the sensor normally open?
Thanks

The carb solenoid is independent of the oil pressure switch. Last time I’m saying it. NOT RELATED. Forget the oil switch.

You obviously do not understand basic DC power flow. 🙄

 

[J. Baker]

Tell you what. Go unplug the oil pressure switch and run it. It will still run just like it always has. Won’t change a thing.

 

[J. Baker]

I guess you don't like to be told you are wrong.

I wasn’t wrong.

You meant to say that the two circuits are not related, but you said they are not connected in the wiring diagram and there is where there was a misunderstanding.

You misunderstood. Not me. My response was clear. You seemed to think the oil pressure switch somehow powered the solenoid. It DOES NOT.

So, I removed from the circuit both the solenoid and the oil sensor, and I was soo happy because for a while I was able to burn rubber and engage the pto....
Until it warmed up.

Told you so.

 

[J. Baker]

I mentioned before that when the engine warms up, I see a drop of oil from the screw of the exhaust manifold of the back cylinder. I wonder if that head gasket is causing the loss of power.

Probably not oil. More likely it is carbon soaked fuel leaking out the exhaust manifold because the coil on that cylinder is already dead and it’s just pumping fuel through it.

But, I can’t see the engine, and we haven’t gotten a video of it running yet. That would be helpful.

 

[J. Baker]

Why belittle others, we get it, you're a "master mechanic" who is now on his third or fourth career after having youthfully "retired" from all the previous ones such as truck driving and what else, now you're already in your second year of landscaping bestowing all your decades of wisdom down unto the rest of these puny mortals over whom you're clearly superior.

That is very interesting and thought provoking, thank you kindly for your thoughts on the matter.

 

[J. Baker]

I will take a video today.
I hope the forum lets me upload it because video files can get big in size.
Thanks

You will have to upload it to a hosting site such as YouTube and link or embed the video here. You can’t upload video directly to this site.