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Sorry if cross-posting isn't allowed; I posted this in the Kawasaki forum but it occurred to me that this might not be motor, but mower related. Anyway, feel free to take this down if I'm rule-breaking.

I'm helping my father-in-law with a Hustler Super Mini Z (927277) with a 25HP Kawasaki carbureted motor. (FH721V-CS16-R)

From cold, the mower runs perfectly until it warms up. As soon as it warms up (about 10 minutes of full-throttle mowing with a bagger, not full speed) the fuel filter runs dry.

I assumed the pump was bad and there were some cracked lines so I replaced everything from the tanks to the carb. (Fuel lines, filter, pump, pulse line... not the 2-way valve) No improvement at all.

I considered the pick up tubes might be clogged but it behaves the same way with either tank, and letting the mower sit for 20 minutes or so, the filter re-fills from gravity alone.

The only thing I can come up with is the pulse line losing pulses.

I'm completely at a loss. The fuel system (cold motor, running on the fuel in the bowl) will fill a 1-gallon gas tank in about a minute. Once the motor warms up, there's no flow (outside gravity) to be found.

when it runs dry, take the line off at the pump where it sucks the fuel up, see if you can feel a pulse.

Does the engine run fine?
Or does the filter look like it is empty?
Clear filters are nothing but trouble.

Scrubcadet10 said:

when it runs dry, take the line off at the pump where it sucks the fuel up, see if you can feel a pulse.

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Sorry, just to clarify; I should feel a pulse at the pump fuel inlet? That makes sense. I'll check that, thanks!

Fish said:

Does the engine run fine?

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Yes, until it dies from fuel starvation anyway!

Fish said:

Or does the filter look like it is empty?

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Yes, when the motor dies, the filter is empty. I can re-start the motor and it will run very briefly at low RPM. Throttling up or even moving (anything that causes more fuel use) will kill the motor again.

Fish said:

Clear filters are nothing but trouble.

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I bought the OEM Hustler filter, which was clear. I asked what was on the Kohler motors and they showed me a similar (slightly larger) clear filter.

Surely there are some quality filters made from clear plastic?

TheRiflesSpiral said:

Sorry, just to clarify; I should feel a pulse at the pump fuel inlet? That makes sense. I'll check that, thanks!

Click to expand...

Sorry, i meant to say where the pulse line hooks to the pump.

TheRiflesSpiral said:

I bought the OEM Hustler filter, which was clear. I asked what was on the Kohler motors and they showed me a similar (slightly larger) clear filter.

Surely there are some quality filters made from clear plastic?

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OEM, ( hustler, kohler, briggs, kawasaki, etc.) are all fine.

Scrubcadet10 said:

Sorry, i meant to say where the pulse line hooks to the pump.

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I was afraid of that; That line is nearly impossible to get to on this motor. The bracket to which the fuel pump is mounted is bolted directly above the port. The line from the manifold to the pump is only about 2" long and makes an "S" shape.

I might try to tie a "T" into it though... or temporarily mount the pump elsewhere so the line could be slightly longer. (Long enough to get it off when it dies)

I'll try that, though. Tired of futzing with it tonight. Thanks for the ideas.

Scrubcadet10 said:

OEM, ( hustler, kohler, briggs, kawasaki, etc.) are all fine.

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Okay, good news. The fact that it's brand new should count for something.

TheRiflesSpiral said:

I was afraid of that; That line is nearly impossible to get to on this motor. The bracket to which the fuel pump is mounted is bolted directly above the port. The line from the manifold to the pump is only about 2" long and makes an "S" shape.

I might try to tie a "T" into it though... or temporarily mount the pump elsewhere so the line could be slightly longer. (Long enough to get it off when it dies)

I'll try that, though. Tired of futzing with it tonight. Thanks for the ideas.

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My mule uses a pump setup like that, and basically uses fuel line for the hose.

Try loosening the cap when it starts to die.

Also, is the tank higher than the carb? If you disconnect the fuel line at the pump, does the fuel flow? If so, drain it into a can and watch things flow.
Is the tank clean, and the screen clear?

Firstly the impulse signal on a twin is a lot less than the impulse signal on a twin
Twin tank set ups are known for debris getting clogged at the tap.
So get some sort of spare tank, pinch it off your push mower if you have to .
When the mower cuts out slip the alternative tank onto the pump and see what happens
Problem goes away = debris restricting fuel supply to pump.
Alternatively you can blow back through the fuel line with the fuel cap off both tanks really hard
Again problem goes away then debris in the fuel lines
I have taken to fitting fuel filters before the tap on multi tank set up to cure this problem

As no one has pot an answer to your other post would you be kind enough to go back to it and in the lower right corner there are 3 green words
Report - Edit - Delete
Hit the delete button to remove the thread

In the previous post I forgot to mention, a piece of tissue ear the end of the impulse line will fluter other wise you will need to use a manometer or the redneck wet finger.
If you get off on fuel vapours you can also pop your tounge over it but don't let the kids see you doing it.

Fish said:

Clear filters are nothing but trouble.

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I have seen many fine running engines with clear filters that look empty. The problem is when the customer sees the phenomenon. He becomes so fixated on it, that anything that happens, in his mind the fault is fuel starvation, and he spends a whole lot of time and money in that direction.
So I stopped selling the clear ones. They were nothing but trouble.

Fish said:

I have seen many fine running engines with clear filters that look empty. The problem is when the customer sees the phenomenon. He becomes so fixated on it, that anything that happens, in his mind the fault is fuel starvation, and he spends a whole lot of time and money in that direction.
So I stopped selling the clear ones. They were nothing but trouble.

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I have one cut in half length wise to show where the outlet is and how you get air trapped in the end.
When fitting them vertical I fit them back to front
Even then some twats argue that they can no work backwards
One way paper ?
I bought a gross of the Isreali duel sized ones so it will be a while before I run out.

Fish said:

Try loosening the cap when it starts to die.

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The cap on the fuel tank? I did try that, no change.

Fish said:

Also, is the tank higher than the carb?

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The fuel tanks are higher than the carb, yes.

Fish said:

If you disconnect the fuel line at the pump, does the fuel flow? If so, drain it into a can and watch things flow.

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If I disconnect the fuel inlet from the pump, gas does flow down into the filter then into the can I use to catch the fuel. It flows pretty fast.

Fish said:

Is the tank clean, and the screen clear?

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It appears to be. Hard to get a good look at it but I'll get a better flashlight out tomorrow and look again.

bertsmobile1 said:

Firstly the impulse signal on a twin is a lot less than the impulse signal on a twin

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This reminds me of a line from the Scott Pilgrim movie... "The movie is much better than the movie..." Sorry I don't know what you mean; I only have twins to compare this one to.

bertsmobile1 said:

Twin tank set ups are known for debris getting clogged at the tap.
So get some sort of spare tank, pinch it off your push mower if you have to .
When the mower cuts out slip the alternative tank onto the pump and see what happens
Problem goes away = debris restricting fuel supply to pump.
Alternatively you can blow back through the fuel line with the fuel cap off both tanks really hard
Again problem goes away then debris in the fuel lines
I have taken to fitting fuel filters before the tap on multi tank set up to cure this problem

Click to expand...

Got it. I do have a spare tank from another mower I can use. The more I think about it the more I think this has to be it. I'm correlating the engine warming up with this problem, but it could be that a full fuel line/filter/carb bowl holds just enough fuel to last that long, and it really has nothing to do with the engine temp.

I've taken tomorrow off so I can devote some time to this beast. It will NOT beat me. ?

bertsmobile1 said:

As no one has pot an answer to your other post would you be kind enough to go back to it and in the lower right corner there are 3 green words
Report - Edit - Delete
Hit the delete button to remove the thread

Click to expand...

Sorry, I only see "Report Edit"

Fish said:

I have seen many fine running engines with clear filters that look empty. The problem is when the customer sees the phenomenon. He becomes so fixated on it, that anything that happens, in his mind the fault is fuel starvation, and he spends a whole lot of time and money in that direction.
So I stopped selling the clear ones. They were nothing but trouble.

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Oh, I see. Yes, I can see how that can happen. A trickle of fuel can flow right through the filter undetected and allow the motor to run fine.

I don't know if it is what is happening in your case, but many folks make an observation of something, and immediately make it in their mind that the problem is there, and have a hard time looking elsewhere.
So the engine runs fine until the engine gets hot?

Way back, the landlord had 2 2000series Cubs ( runs 5 now )
One had a hood & one did not
The one with the hood would run 1/2 hour to an hour then peter out till it got cold then it would be fine for another 1/2 to 1 hour.
The one with no hood would run all day so we naturally looked at overheating .
A full year latter I went to change the fuel filter as I could see it was dirty
We had been through all that "looks empty rubbish "
Well the mower was full of petrol and pointing down hill so I clamped the fuel line then changed the filter
And sure enough when the clap came off. no fuel came out .
So next thought was collapsed fuel line so I blew back through it then nearly drowned in the gushing fuel
Mower ran fine for its usual time & every time it stopped we blew back and away it went
Now it is a big job to get that tank out, but we did and then strained the fuel
We ended up with a golf ball sized clump of old TRANSPARENT grass clippings .
From that day on a 2 liter fuel tank of a 11 Hp Tecumseh became a std diagnostic tool , kept in the service van.
Around 1/4 of the runs fine then stops jobs end up being trash / water in the fuel tank

TheRiflesSpiral said:

This reminds me of a line from the Scott Pilgrim movie... "The movie is much better than the movie..." Sorry I don't know what you mean; I only have twins to compare this one to......

Click to expand...