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slowindown

Mower engine hot start issue

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It ran good, not a real noticeable difference.  After mowing the last of my grass, I let it idle a bit and cut it off.  I tried to restart it hot.  It would not start.  I pulled the choke.  It started.  I pushed the choke off and it would idle and run fine up to about half throttle.  Over that, it wouldn't plane out and would puff kinda black smoke and run poorly.  It has done that on a number of hot start occasions in the past.

 

Oddly, one of my friends and his dad bought 2 of the exact same mowers with the same engine as mine at roughly the same time as mine.  They have roughly the same hours on theirs' and probably don't take care of them as well as I do mine.  They do not experience this issue.

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Posted (edited)

Does anyone know what this thing in the picture is?

It appears to be in a fuel line?? A vent maybe??

 

 

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Edited by slowindown

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That's interesting.  Does your cap vent?  If not, that might be a fuel tank vent....with a clogged filter.

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Posted (edited)
51 minutes ago, 56Sierra said:

That's interesting.  Does your cap vent?  If not, that might be a fuel tank vent....with a clogged filter.


Well I dug through the owners manual and apparently it is a “fuel evaporation system filter”. And apparently it is supposed to be replaced every 300 hours. I used my best google-fu but could not find a part listing for it. I just kept coming up with the fuel filter. So I took it off and cleaned the two little filters in it and put it back. See pic. They were almost totally caked up before that pic. 
 

As to whether the caps are vented, I don’t know. There’s a pic below. They’re like a car in that when you tighten them, they start clicking. Also in that pic you can see two fuel lines from each tank. The larger 1/4” lines go to the tank selector/fuel shut off valve. The 1/8” lines go to that little evap filter. And then there’s a T in the 1/8 in line and the T’d line goes up and plugs in the side of the carb, so I guess it’s some epa thing where the engine burns vapors from the tank, so maybe they’re not vented other than that filter???

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Edited by slowindown
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Could be made to California Emissions , my Honda clone has a set up like that and it had a California tag on the engine 

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Posted (edited)
22 minutes ago, Fishfiles said:

Could be made to California Emissions , my Honda clone has a set up like that and it had a California tag on the engine 

 

Been reading some... Apparently after '11 or '12 they all had some sort of emission doodad on them.  My mower is a '13. Some, maybe later ones have charcoal canisters.  I finally found a listing for that part, btw https://www.hustlerlawnmowerparts.com/hustler-part-603024/ pricey.

 

Speaking of pricey, it's time I change the hydraulic filters and fluid for the transaxles.  $35 for two hydro gear brand filters from amazon (that mower has a pair of hydro gear zt-3100 transaxles).  Fortunately, the original recommended fluid was castrol 20-50 motor oil in the transaxles.

Edited by slowindown
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3 hours ago, slowindown said:

I let it idle a bit and cut it off.  I tried to restart it hot.  It would not start.  I pulled the choke.  It started.  I pushed the choke off and it would idle and run fine up to about half throttle.  Over that, it wouldn't plane out and would puff kinda black smoke and run poorly.  It has done that on a number of hot start occasions in the past.

 

now it sounds like a carb or that emissions issue, I'm still baffled as to why it won't do this cold, but rather when the engine is up to operating temperature but i agree with @Mistercleanlet me ask this... when you take ether of gas tank caps off, notice any hissing sounds ? right after it's been running, or even over night >> (when it's had time to cool all the way down) 

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This sounds similar to a problem with a car I bought.  It would vapor lock.  There's a valve on the gas tank that was designed to let air in as the gas was used but hold around 3 PSI before it vented to the charcoal canister.   It was installed backwards.  

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3 minutes ago, _Wilson_™ said:

 

now it sounds like a carb or that emissions issue, I'm still baffled as to why it won't do this cold, but rather when the engine is up to operating temperature but i agree with @Mistercleanlet me ask this... when you take ether of gas tank caps off, notice any hissing sounds ? right after it's been running, or even over night >> (when it's had time to cool all the way down) 

 

I've not noticed any hissing sounds that I recall.  And I think I've switched tanks right before cutting it off or opened the gas cap to test what your getting at but not 100% sure.  I'll see if there are any changes when I cut next weekends grass.

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2 minutes ago, 56Sierra said:

This sounds similar to a problem with a car I bought.  It would vapor lock.  There's a valve on the gas tank that was designed to let air in as the gas was used but hold around 3 PSI before it vented to the charcoal canister.   It was installed backwards.  

 

Now that's an interesting thought.  While I bought this mower new, I don't know if that part with the filter is open or has some sort of check valve in it which might be malfunctioning.  In the parts listing I linked above, unlike the manual it's called a "vacuum breaker," whatever that is.

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1 minute ago, slowindown said:

 

Now that's an interesting thought.  While I bought this mower new, I don't know if that part with the filter is open or has some sort of check valve in it which might be malfunctioning.  In the parts listing I linked above, unlike the manual it's called a "vacuum breaker," whatever that is.

it should keep the fuel tank from vapor locking, and not allowing the fuel tank to vent from the sounds of it.

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If you can figure out a way to let the cap vent air in you'll eliminate that or prove it.

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12 hours ago, slowindown said:

 

Fortunately, the original recommended fluid was castrol 20-50 motor oil in the transaxles.

The recommend hydraulic oil for my zero swing Husqvarna drive system is the same oil Castrol 20w50 

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Oh , I think I would ditch the " fuel evaporation system filter " in favor of atmospheric evaporation and keep the bucks in the pocket instead of China's  

 

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agreed ^^^ 100% i find it redicious to have a system like that on a mower, or any small engine powered machine.... the EPA needs to figure on deferent things, like cutting back the money they waist, and rules that make little to no sense at all, but cost company's and  us in the long run dealing with problems. 

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15 hours ago, slowindown said:

 

I've not noticed any hissing sounds that I recall.  And I think I've switched tanks right before cutting it off or opened the gas cap to test what your getting at but not 100% sure.  I'll see if there are any changes when I cut next weekends grass.

Are you going to make us wait until the weekend to see if this fixed it?  Don't you have a neighbor that needs their grass cut today?😉

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6 minutes ago, 56Sierra said:

Are you going to make us wait until the weekend to see if this fixed it?  Don't you have a neighbor that needs their grass cut today?😉

I definitely wont have time to touch it today and probably not tomorrow, possibly Wednesday after work.  I do want to pull that part completely off and see if there is any sort of check valve in it.  I also want to open the cap for a few seconds before I turn it off hot and a few other things.  

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Let's not make this difficult. The mower started when hot with starting fluid and ran fine correct? This says ot was mot getting fuel correct? Unless there is more information that we don't know, them the problem is fuel delivery.  When the fuel boils it can't pump or even gravity feed thru the filter. The fuel must be boiling. Yes, even if it didn't do this when new. It doesnt.matter why.......it just does. You have cleaned the cooling fins so the only thing left to do in to insulate every fuel component you can between the fuel tank to the intake manifold.  This is an air cooled machine and they can get very hot .........Too hot for some fuels. This may be a symptom that isn't repairable but it's worth a try.

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Fuel boils because of heat and reduced ambient pressure.   If his tank wasn't venting properly the fuel may boil.  The fuel pump, if there is one would have increased the pressure enough for the fuel to remain below the boiling point.  Shut the engine down, the pressure drops and vapor lock occurs.  Picture opening a soda bottle.  The CO2 comes out of solution or a diver accending too quickly and nitrogen boiling if his/her blood.

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heck..i'm ready to toss a .99 cent for sale sign on it, be done with it !..rofl. j/k slow..hopefully yu'll get it fixed !.

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7 hours ago, Fishfiles said:

The recommend hydraulic oil for my zero swing Husqvarna drive system is the same oil Castrol 20w50 

 

By the way, they have Castrol GTX 20w50 for $19.32 for a 5 qt bottle at walmart, which is about what mine takes.  So, not bad.

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4 hours ago, 56Sierra said:

Fuel boils because of heat and reduced ambient pressure.   If his tank wasn't venting properly the fuel may boil.  The fuel pump, if there is one would have increased the pressure enough for the fuel to remain below the boiling point.  Shut the engine down, the pressure drops and vapor lock occurs.  Picture opening a soda bottle.  The CO2 comes out of solution or a diver accending too quickly and nitrogen boiling if his/her blood.

 But, it started when primed and ran good. That alone eliminates your theory. 

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35 minutes ago, Misterclean said:

 But, it started when primed and ran good. That alone eliminates your theory. 

No, it doesn't.   getting it started on a prime allows the fuel pump time to pick up fuel and fill the carb bowl. 

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17 minutes ago, 56Sierra said:

No, it doesn't.   getting it started on a prime allows the fuel pump time to pick up fuel and fill the carb 

5 hours ago, 56Sierra said:

Fuel boils because of heat and reduced ambient pressure.   If his tank wasn't venting properly the fuel may boil.  The fuel pump, if there is one would have increased the pressure enough for the fuel to remain below the boiling point.  Shut the engine down, the pressure drops and vapor lock occurs.  Picture opening a soda bottle.  The CO2 comes out of solution or a diver accending too quickly and nitrogen boiling if his/her blood.

Increased pressure LOWERS the boiling point. It would also push fuel to the carb thru the pump to the carb. Unless there is important information missing or some of the information is incorrect then my theory holds the high ground. I've been doing this since June of 1983 professionally. I'm not going to argue this any longer.

 

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