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Got a tricky one. Need thoughts. Deere 375R. 25hp Briggs. Was surging and dying after ~ 1.5-2 hours of mowing. After carb work, ended up replacing with OEM carb. Removed and cleaned fuel tank. Blew out all fuel lines. Replaced fuel line from fuel tank to carb. Replaced fuel filter and fuel pump. Replaced both ignition coils. All to no avail. Brought to JD dealer and they ran it several times for extended amounts of time and tested under load in thick grass and it never missed a beat. Took it home and 20 minutes into mowing, started surging and dying again. Thought maybe bad gas, but I’m running our 355E on the same gas without issues. So both I and the mechanics at the JD dealer are stumped. Insight appreciated.

Jim

Did you clean out the fuel tank? I had one earlier this year that was giving and between a honey and a yellow jacket that being suck up the fuel pickup the engine was dying. The pickup is large enough for these to get suck up but they couldn't get the restriction in the line. With engine off they just settle back out and had to be suck up again when they came close to the pickup tube. Timing was different depending on where they got washed to in the tank.

So you may trash in your tank too. Worth checking but getting the pickup out is a pain but that is about only to look inside the tank.

StarTech said:

Did you clean out the fuel tank? I had one earlier this year that was giving and between a honey and a yellow jacket that being suck up the fuel pickup the engine was dying. The pickup is large enough for these to get suck up but they couldn't get the restriction in the line. With engine off they just settle back out and had to be suck up again when they came close to the pickup tube. Timing was different depending on where they got washed to in the tank.

So you may trash in your tank too. Worth checking but getting the pickup out is a pain but that is about only to look inside the tank.

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Yessir. My next move was actually to pull tank and have another look at it.

Get your hands on another fuel tank , some 1/4" fuel line & 2 fuel taps
There are hundreds of old tanks out there from all the old gravity fed ride ones that died
Put a long fuel line on it with a tap and fit the other fuel tap on the existing fuel line between the tank & pump then 1/2 fill the spare tank and go mow
When your mower plays up slip the alternative tank directly onto your cab .
Expect the mower to run a tad slower but if the problem goes away you know it is the fuel supply
If not then you know it is in the engine .
IF it mows OK then shift the alternative tank to the fuel pump and see what happens.

Let us know how you go for further tests / instructions

bertsmobile1 said:

Get your hands on another fuel tank , some 1/4" fuel line & 2 fuel taps
There are hundreds of old tanks out there from all the old gravity fed ride ones that died
Put a long fuel line on it with a tap and fit the other fuel tap on the existing fuel line between the tank & pump then 1/2 fill the spare tank and go mow
When your mower plays up slip the alternative tank directly onto your cab .
Expect the mower to run a tad slower but if the problem goes away you know it is the fuel supply
If not then you know it is in the engine .
IF it mows OK then shift the alternative tank to the fuel pump and see what happens.

Let us know how you go for further tests / instructions

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Should “cab” say “carb”? Never thought of this to diagnose fuel delivery! Thanks.

Fat fingers, yes CARB .
Easiest way to rune some thing out is to replace or bypass it.
That is why you start with a direct connection to the carb then go back one element to the fuel pump
If it is a fuel supply problem you can go one step further back & hook the alternative tank to the fuel lines at the original tank
If all id good then it is the tank
Some JD tanks draw the fuel up using a standpipe hanging down from the top of the tank and these have been known to fracture or crack so once the fuel gets to a particular level then the mower starts to suck air .
PIA to get the tank out but easy to use an alternative tank
I use some from old 8 hp Tecumsehs that were engine mounted & came with an inbuilt tap .
Holds about 1/2 gallon.

Thanks!

Something like this can "slow down" trash getting into the tank. Simple fuel cap strainer.

slomo said:

Something like this can "slow down" trash getting into the tank. Simple fuel cap strainer.
View attachment 61577

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I have a funnel with built-in screen. But this is also a good idea

kajnjim said:

I have a funnel with built-in screen. But this is also a good idea

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Finally able to get back to mower. After much contemplation, I decided the problem must be fuel delivery pre-engine. I blew out all the lines again and replaced fuel tank. So far, so good. Time will tell. Thank y’all.

Jim

kajnjim said:

Finally able to get back to mower. After much contemplation, I decided the problem must be fuel delivery pre-engine. I blew out all the lines again and replaced fuel tank. So far, so good. Time will tell. Thank y’all.

Jim

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Bingo! Mowed for 4 hours without a hiccup. Now for an autopsy on the old fuel tank to see exactly what the problem was.

kajnjim said:

Bingo! Mowed for 4 hours without a hiccup. Now for an autopsy on the old fuel tank to see exactly what the problem was.

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For anyone that’s curious, the results of the autopsy are in. Cut bottom of tank out. Floating in the unremovable fuel that was left in the tank was a piece of leaf about 3/8 X 5/8 inches. Just the right size to get sucked up against and block the 1/4” ID fuel line inside the tank. So after 3 months of swapping umpteen engine parts and stumping the entire service department at JD and myself, the mystery is solved. Guess I’ll epoxy the fuel tank back together after cleaning and I’ll have a spare that I’ll likely never need. Can bet your sweet a$$ all fuel will now go through strainer funnel. . Thanks all.

Jim

Weld the tank
Epoxy will fail when you least expect it to
BBQed mower leaves a bad taste in your mouth
Those creamy looking milk bottles are HDPE the same material as the fuel tank
So it is clean the plastic, V out the joint just the same as stick welding and weld the seam.
File smooth than put a patch plate over the top with a hot air gun
Lots of reasonable videos about plastic welding on line just ignore the comments about using old zip ties for everything.
You must use the same plastic filler as the parent metal otherwise it will look good then fall out when the tanks gets hot.

bertsmobile1 said:

Weld the tank
Epoxy will fail when you least expect it to
BBQed mower leaves a bad taste in your mouth
Those creamy looking milk bottles are HDPE the same material as the fuel tank
So it is clean the plastic, V out the joint just the same as stick welding and weld the seam.
File smooth than put a patch plate over the top with a hot air gun
Lots of reasonable videos about plastic welding on line just ignore the comments about using old zip ties for everything.
You must use the same plastic filler as the parent metal otherwise it will look good then fall out when the tanks gets hot.

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Sounds good. Thanks.

Jim

kajnjim said:

Got a tricky one. Need thoughts. Deere 375R. 25hp Briggs. Was surging and dying after ~ 1.5-2 hours of mowing. After carb work, ended up replacing with OEM carb. Removed and cleaned fuel tank. Blew out all fuel lines. Replaced fuel line from fuel tank to carb. Replaced fuel filter and fuel pump. Replaced both ignition coils. All to no avail. Brought to JD dealer and they ran it several times for extended amounts of time and tested under load in thick grass and it never missed a beat. Took it home and 20 minutes into mowing, started surging and dying again. Thought maybe bad gas, but I’m running our 355E on the same gas without issues. So both I and the mechanics at the JD dealer are stumped. Insight appreciated.

Jim

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We have a 2010 JD Z425 with the L44 twin B&S 23 hp engine and it did the same thing the third year we had it. Just out of the blue it would start surging and die like it was out of fuel. It did have plenty of fuel. Wouldn't start back up. Let it sit 20 min. or so and tapped the carburetor and it started right up. Did this several times during that season and a couple of times the next season. Has never done it again since. I believe it was a hang up of the carburetor float for some odd reason. Never disassembled the carb or anything else but it has never done it again.

rpnelson said:

We have a 2010 JD Z425 with the L44 twin B&S 23 hp engine and it did the same thing the third year we had it. Just out of the blue it would start surging and die like it was out of fuel. It did have plenty of fuel. Wouldn't start back up. Let it sit 20 min. or so and tapped the carburetor and it started right up. Did this several times during that season and a couple of times the next season. Has never done it again since. I believe it was a hang up of the carburetor float for some odd reason. Never disassembled the carb or anything else but it has never done it again.

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Well that brought back an awesome memory. My first JD ZTR was a Z425. My wife (who does 90% of the mowing) came to me one day and said it died and wouldn’t start back up so I turned it over and heard the most God awful noise from the engine. Removed engine and as soon as I got in it, I saw pieces of pistons and rods and cam shaft all over the place. I found an engine for $80 (pretty sure it was to fund the dudes meth habit) and put it on that Z425. Only problem was it had a different orientation than the original, so in order to get the cables connected to the carb, the engine had to be mounted 90° from how the original was. Was able to get everything connected except the muffler. I still have it as an emergency use mower, but can only use it if I wear earplugs. My wife wouldn’t think of using it. The neighbors really enjoy it. . It’s actually my second back up. I also have a Z355E that my wife does use as her backup. Which she did often during this saga.

Bettsmobile,
Followed your advice and did my first ever plastic welding on that tank. It was kinda fun and came out excellent. Can’t even tell it was cut into if you stand far enough away. . Thanks for the tip.

Jim

Glad it worked for you.
Provided you did not over heat and drive the plasticisers out so it is brittle it will be as good as new .

Well…bad news. Thought I had it solved, but yesterday when the wife was mowing it started again. Just on a whim, I swapped the gas cap with the 355E thinking maybe a tank vent problem, but of course that did nothing. I’m kinda leaning toward a governor problem, but not being a small engine mechanic, I’m not familiar enough with what other components and their settings/adjustments/relationship to the governor would affect the way the governor affects the way the engine runs other than the speed of the camshaft. Or am I barking up the wrong tree. Should I be looking somewhere else. Kinda lost.

You said your wife does most of the mowing. Congrats on that. Anywhoo, I was wondering is she a petite gal at 92lbs or a healthy girl? Wondering if she is lifting out of the seat causing the seat switch to open up killing the coil/s? Hitting bumps......

Next thought was check all safety switches and wiring. Clean/polish all connections and goop some dielectric grease where possible. Play around with the switch plungers and a multi-meter. Barely push in numerous times then give it the full gundy several times. Go to the next switch. Could be a bad wire too. Old mower, might be time to rewire all the switches.

slomo said:

You said your wife does most of the mowing. Congrats on that. Anywhoo, I was wondering is she a petite gal at 92lbs or a healthy girl? Wondering if she is lifting out of the seat causing the seat switch to open up killing the coil/s? Hitting bumps......

Next thought was check all safety switches and wiring. Clean/polish all connections and goop some dielectric grease where possible. Play around with the switch plungers and a multi-meter. Barely push in numerous times then give it the full gundy several times. Go to the next switch. Could be a bad wire too. Old mower, might be time to rewire all the switches.

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First off…I will not answer the first question just in case she ever comes across this thread. . Definitely not the issue though. I have the seat switch bypassed. Anything else besides cutoff wire at coils and carb?

kajnjim said:

First off…I will not answer the first question just in case she ever comes across this thread. . Definitely not the issue though. I have the seat switch bypassed. Anything else besides cutoff wire at coils and carb?

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Remove the coil cut off wire. Go mow. Should run the tank dry as long as the coils don't get hot and cause a spark issue.

You still need to check all the safety switches and wiring. Unless you find out something from the above comment.