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Air cleaner indicates it is a FD750D 27hp, the sticker on valve cover shows it MFG date of 07/05, engine family KAXS, 745N4CA. It is in my 2008 Simplicity Legacy Mini Tractor with 1k hrs I am the 2nd owner, It has run fine for me the whole 100+ hrs I have had it. I've Goggled till I can’t Goggle anymore. I was going to change the coils next but I do not think both would quit working at the same time. When it quits running it's like the key was turned off. It will run for 10 minutes when cold, (runs great), let it sit for 5 minutes restart and runs for a couple minutes. It will die at full throttle with the blades engaged and when just trying to baby it back to the garage. I've done all prelems, Vent on gas cap (even ran it loose) new fuel filter (clear with fuel flow), new pump (working to carb) new battery (all connections are clean) (I haven't check the engine ground I guess that's next but does not make sense about it restarting right away). New plugs (looking good but only have 20+ minutes on them. Oil and filter newer (10 hrs) and level good. Someone please HELP. I've got 7 acres of 12" high grass and weeds to mow. I am posting this on the Simplicity thread as well

Junk in the fuel tank getting picked up and cutting fuel flow? Is the fuel pump working correctly? Should flow 6-7 oz of fuel in 30 seconds at between 2.5 - 3 psi. Try gravity feeding fuel directly to the carburetor. These would be my thought. Doesn’t seem electrical if it will start right back up.

No junk in the tank, In original post. new fuel filter shows fuel flow, new fuel pump is pumping. If those were the issue I can only assume it would not run at full throttle with load for 10 or so minutes

in the post, It does not start right back up it has to sit for 5 or so minutes to run for a minute or two, and if completely cold will run for 10m or so minutes. When it does quit it is like the key was turned off. Not like it was running out of fuel.

There is nothing on the engine that is going to reset itself after 5 minutes of sitting. I would focus on the safety system next. Seat switch, other switches.

Thanks for the input, The only reset issue (if one were to call it that)

I can imagine, may be one device that is failing when the engine comes to temperature,

Which would allow or disallow spark to both plugs.

I do not think it is a reset issue, as the time difference between it being cold and running till it stops is 10 or so minutes,

which is different that waiting 5 minutes after a shut down and restart and running for only 2 minutes or so. Both times are somewhat consistent

As you stated, it would be very unlikely but not impossible that both coils would fail at the same time. And, the coil will actually get hotter (heat soak) for up to 5 minutes after the engine stops.

So are you saying there is not one item that controls spark to both coils?

Are the coils not connected to the battery via the regulator?

I am very familiar with 5hp pull start and automotive engines, not these larger small engines

The coils a self energising so they are not connected to the battery and doing so will fry them in no time flat
For the purpose of testing you can remove the kill wires from the coils
The Kawasaki manual shows them as being white while the Simplicity manual shows then as being violet .
That engine has a low oil warning system as well .
On the earlier models it just went to a warning light on the dash but I have a feeling the latter models it was connected to an ignition cut out
So if the oil level is a little low, after a couple of minutes of running the oil that was in the sump gets distributed all over the engine, causing the sump level to drop activating the low oil shut down.
After sitting for a few minutes the oil drains back into the sump so the ignition circuit is good to go again.
I was sure I had a late model diagram I can not find it
Simplicity have all of their manuals on line but you will need to use the model number to get them
Simplicity web page
If you post your full model number off the ID tag
If you post it here as well we can look up your exact wiring diagram so we don't give you a bum steer.

bertsmobile1 said:

The coils a self energising so they are not connected to the battery and doing so will fry them in no time flat
For the purpose of testing you can remove the kill wires from the coils
The Kawasaki manual shows them as being white while the Simplicity manual shows then as being violet .
That engine has a low oil warning system as well .
On the earlier models it just went to a warning light on the dash but I have a feeling the latter models it was connected to an ignition cut out
So if the oil level is a little low, after a couple of minutes of running the oil that was in the sump gets distributed all over the engine, causing the sump level to drop activating the low oil shut down.
After sitting for a few minutes the oil drains back into the sump so the ignition circuit is good to go again.
I was sure I had a late model diagram I can not find it
Simplicity have all of their manuals on line but you will need to use the model number to get them
Simplicity web page
If you post your full model number off the ID tag
If you post it here as well we can look up your exact wiring diagram so we don't give you a bum steer.

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Riding mowers do not have a low oil shutdown. At least not in the US. This is not OSHA compliant.

Got 2 Dixons in the run
one has a low oil switch that will not allow the engine to crank
the other has a low oil switch that also trips a relay that shuts down the engine
I thought this mower had a tilt switch because it would stop when the customer was mowing his fence line which is on a compound slope
Then I would roll it to the flat to work on & it would fire right up
So after ripping it apart I realised it was the oil switch , by disconnecting it .
Trained the customer to mow the fence line in the opposite direction, problem solved.
Some of the older Honda horizontal shaft engine had a low oil shut down
And think the Kohler fitted to a Troy Built sub compact tractor had a low oil shut down but that customer died a while back .

Bdent said:

No junk in the tank,

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That you can see??

Or confirmed blown out and flows freely?

Bdent said:

new fuel filter shows fuel flow

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No it doesn't. FIlters only show there is gas inside them.

Bdent said:

new fuel pump is pumping

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Have you verified this into a glass jar or 5 gallon bucket? Should drain your tank dry if the pump is good.

Any and all new parts will require testing. New is not new any more.

Where are you at on this repair?

late to the party but we run into things like this in cars. If there are any electronics that control the ignition or fuel system, and they have a thermal problem it becomes heat related. We have also seen it where over time an ignition switch goes bad. When it does it expands with the electricity going thru it. That heat causes the contacts to fail. It cools and works again. I would think any safety switch, or ignition switch could be suspect. So could any connections where two wires go together and a little corrosion has gotten into it. I don't know your mower electronics, but a couple sets of jumper wires might help figure which switch it is that is causing the problem. Just don't leave them there when you figure out what it is - replace the defective part.

Remember - fuel and air, compression and ignition are the three things needed to make it run. Your first job is to figure which of the three is missing when it dies. I did not see in the month of discussion where the actual cause (which of the three) was determined to be the culprit.

I am having a similar problem. Replaced both coils, one with after market and now with Kawasaki coils. New spark plugs. New fuel filter. New battery. Even though the fuel caps vents didn't look clogged, tried running it with the caps loosened. Still runs for a few minutes, runs great and then shuts off. Sometimes when I switch fuel tanks it starts back up but stops again in a few minutes. Like it is running out of gas. Now the mower, Hustler Mini-Z, has over 500 hours on it and I bought it used in 2008, it has never given me a problem. I only use 93 octane gas with StaBil 360 in every load. They only thing that I have not done is replace the fuel lines or fuel pump? Could it be one of these?

denisp said:

Could it be one of these?

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Yes.

Dump and flush out your tanks. Install new fuel line from tanks to carb. New filter and shutoff would be nice. Verify good flow AT carb into a glass jar or 5 gal bucket.

Or fix up an IV bag or alternate fuel tank and see how she runs.

On a 15 year old mower, I would replace and TEST all wear items like fuel lines, adjust valves, clean cooling fins and de-carbonize the cylinders. Lap the cylinder heads and block faces. Torque and retorque the head bolts.

Inspect/adjust valves yearly. Only takes a few minutes. Ensures a good running engine. Same for cooling fins and block cleanliness, yearly or more often if bagging/scalping.

slomo said:

Yes.

Dump and flush out your tanks. Install new fuel line from tanks to carb. New filter and shutoff would be nice. Verify good flow AT carb into a glass jar or 5 gal bucket.

Or fix up an IV bag or alternate fuel tank and see how she runs.

On a 15 year old mower, I would replace and TEST all wear items like fuel lines, adjust valves, clean cooling fins and de-carbonize the cylinders. Lap the cylinder heads and block faces. Torque and retorque the head bolts.

Inspect/adjust valves yearly. Only takes a few minutes. Ensures a good running engine. Same for cooling fins and block cleanliness, yearly or more often if bagging/scalping.

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Thank you very much. Weekend project! I will let you know how I make out.

denisp said:

Thank you very much. Weekend project! I will let you know how I make out.

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Please do. Not many come back and say hey THANKS guys. I fixed it with xxxxxxx xxxxxxx. Will help others if you report a good fix action.

denisp said:

Thank you very much. Weekend project! I will let you know how I make out.

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OK, so I drained both fuel tanks. Replaced all the fuel line. But when I went to blow out the elbow that comes out of each fuel tank, there must be a check valve inside the tank. I noticed that there wasn't any air coming out of the top. Pressure was building up in the elbow and when I took the air nossle out of the elbow it blasted a mist of gas into the air. Certainly glad I had safely glasses on! It is still having the same problem. The only thing I have left to do is take the tanks off and remove the elbows from the tank. That scares me because I don't know how I am going to put the elbows back in. They are the opposite corner's of the cap. Any suggestions on that?
Thanks for your help.

Neever seen a check valve in a fuel tank
Have seen a lot of debris blocking outlets though
Simple check it to make a bung for your air line to fit fairly tight into the filler hole and bow compressed air into the tank CAEFULLY
If it is a check valve then air should blast out of the elbows
IF it is a blockage the tank will just expand ( can pop thus the "carefully:

bertsmobile1 said:

Neever seen a check valve in a fuel tank
Have seen a lot of debris blocking outlets though
Simple check it to make a bung for your air line to fit fairly tight into the filler hole and bow compressed air into the tank CAEFULLY
If it is a check valve then air should blast out of the elbows
IF it is a blockage the tank will just expand ( can pop thus the "carefully:

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I will try that. There can't be that much stuff in the bottom. I'm the one who has put gas in it for 90% of the fills since I've owned the mower. And both tanks? It's really weird. Thank you for the advice!

HUSTLER 791277 - FTG FUEL TANK 90 d​

This is the part that I am talking about. Would you know how to change this out of the tank without taking the tank off of the mower? There are two saddle tanks and this part goes in the exact opposite end of the tank. Is there a trick to get it to the bottom of the other end?