Mower won’t start hot

[Greenlawnracing]

My 5ish year old Troy Bilt push mower won’t start hot. Runs fine, but if I have to add fuel or open the gate it won’t restart.

Google says to replace the coil and carb.


What says the all knowing GJ?

 

[cgrutt]

Pull the plug and check condition/gap. Check for spark. If you're getting spark coil/plug/wire probably good need to check if you're getting fuel could be carb. If no spark pull plug off wire and see if you get spark off wire if you do coil probably OK and plug is probably bad. If no spark likely coil but could also be electrical issue such as bail switch etc. I had a mower that had this issue and it turned out to be a small crack in flywheel. That was a PITA to diagnose lol. Good luck!

 

[four.cycle]

what engine does it have on it?
model number of the mower on a Toro walk-behind is under the discharge flap on a white label - driver's side. lift up the black flap to see it.
5-digit number like.... 20024 or something like that.

some Tecumeseh engines had a design flaw in the OEM fuel cap that caused a vapor-lock condition.

if it's got a Tecumseh on it, run it until it stops. remove fuel cap. replace fuel cap. pull rope.
start?
buy a new fuel cap.
no start?
start looking elsewhere.

applies only to Tecumsehs - not B&S ... I think... LEV120 and such...

 

[Greenlawnracing]

what engine does it have on it?
model number of the mower on a Toro walk-behind is under the discharge flap on a white label - driver's side. lift up the black flap to see it.
5-digit number like.... 20024 or something like that.

some Tecumeseh engines had a design flaw in the OEM fuel cap that caused a vapor-lock condition.

if it's got a Tecumseh on it, run it until it stops. remove fuel cap. replace fuel cap. pull rope.
start?
buy a new fuel cap.
no start?
start looking elsewhere.

applies only to Tecumsehs - not B&S ... I think... LEV120 and such...

I think I read that when searching, but is a B and S.

Also just realized I wrote Toro instead of Troy Bilt. Edited to update. It’s a TB210

 

[four.cycle]

^ sorry, can't even begin to guess because I never worked on those later B&S motors much.... only old flatheads and almost all Tecumsehs.

 

[dvblanch]

Has heat activated automatic choke ? Still needs fuel to start even warm

 

[rharman]

As I recall, when I had that issue with a Craftsman mower years ago, it had a cracked valve.

Could be a leaky head gasket too.

 

[d.mcfarland]

That's all the longer the manufacturers hope the mowers make it these days.

Carb is heating up and sticking, leading to flooded engine after shutoff is my guess.

Major carb disassembly and rebuild / or a product like mechanic in a bottle that might dissolve the gum/varnish.

 

[Ole Slewfoot]

Puff of ether when it won't start hot.
Starts=fuel supply problem.
Though fuel oversupply is not ruled out.
No-start pull the plug wire, stick some random other spark plug in it with the threaded part grounded and give it a pull.
No spark=ignition problem.
Spark=pull the plug, and try the one from the mower.
This should at least get you barking at the right tree pretty quick.

 

[Sumboodie]

Where are you mowing grass in winter?
I snowblowed my door yard yesterday!

 

[Greenlawnracing]

Puff of ether when it won't start hot.
Starts=fuel supply problem.
Though fuel oversupply is not ruled out.
No-start pull the plug wire, stick some random other spark plug in it with the threaded part grounded and give it a pull.
No spark=ignition problem.
Spark=pull the plug, and try the one from the mower.
This should at least get you barking at the right tree pretty quick.

I tried ether and a new plug. Coil?

 

[Mick56]

I would check the valve lash. When it warms up, the lash could close up enough to hold a valve slightly open.

 

[jimgood]

I tried ether and a new plug. Coil?

Always begin with the simple stuff. You haven't even said whether you checked for spark so replacing the plug or the coil might be pointless (no pun intended).

 

[bwringer]

I would check the valve lash. When it warms up, the lash could close up enough to hold a valve slightly open.

I've seen a sticky valve do this as well.

 

[Greenlawnracing]

Always begin with the simple stuff. You haven't even said whether you checked for spark so replacing the plug or the coil might be pointless (no pun intended).

I don’t recall - I THINK I checked spark? I did see that the plug was fouled so I replaced it

 

[Ole Slewfoot]

I would check the valve lash. When it warms up, the lash could close up enough to hold a valve slightly open.

Especially with the decompression bump in the cam.

 

[I-pik-up-dead-mowers]

I don't normally give suggestions since I don't have much talent/knowledge but this problem perplexed me. And I haven't seen this "fix".

I had the same issue -- cold, 1st pull start, warm no start until cold again. I replaced coil with no success.

What turned out to be was something to do with the kill wire from the coil to the bail lever/switch. I have no idea why it happens when warm (I assume something expands, creating ground, or spark jumping etc).

So here's my troubleshooting steps-- no spark when warm (pull and ground plug and watch for spark when pulling rope). Good spark when cold. I confirmed this by squirting starting fluid in and I would get NO TURNOVER when warm (sign of no spark as well)

Pull the kill wire off coil either at coil or at the bail switch where the bail lever creates the ground (little wire off coil with spade bit). Try to see if you recreate problem when warm. (remember, you'll only be able to stop the engine with no kill wire by manual touching it to ground or visegripping fuel line to starve engine. If engine starts when warm, you have some sort of kill wire issue -- I couldn't fix it at the bail lever by bending the ground connection.

So what I did was put a cheap switch on a random area of the mower and wired the kill wire to it with another wire to a ground area. Pressing that switch kills the engine (so I can pick up a hose, safely empty clippings, stop for a drink etc). Grounding the wire manually works but might not be very friendly to my wife if she ever mows.

Good luck.

 

[rust in the eye]

A very dirty air filter can cause hot starting problems.

 

[seber]

This is a six month old thread. I suspect the problem has been solved by now. Most likely by a new coil.

 

[theoldwizard1]

I assume it re-starts if it cools down, correct ?

Vapor lock ! Swapping parts will probably NOT fix it.

Do NOT refuel when hot. If you shut down for any reason and need to start up again soon, make sure to park it in the shade.

 

[Bert_]

I've got this problem with the Kohler in my mower. Bought an aftermarket coil a couple years ago to try and it didn't work at all. Kohler part is like $250. I just leave it running until I'm done. Rarely a reason to shut it off anyway

 

[Greenlawnracing]

This is a six month old thread. I suspect the problem has been solved by now. Most likely by a new coil.

Actually I haven’t touched it! Been limping it by all year

 

[Wamsutta]

Actually I haven’t touched it! Been limping it by all year

Is it one of those engines where all you do is pull the rope to start? Automatic choke?

 

[Greenlawnracing]

Is it one of those engines where all you do is pull the rope to start? Automatic choke?

Yep. No primer or anything

 

[seber]

Have you checked for spark?

 

[Greenlawnracing]

Have you checked for spark?

I THINK so. It was last summer so I can’t confirm that I did

 

[loganb]

Never heard of the pet name "mower" for their wife...maybe find a new name and see if that helps?

 

[I-pik-up-dead-mowers]

I just fixed another 20 yr old craftsman mower AND a recent troy bilt trimmer that both had electrical issues with the kill wire... the mower had a worn out bail lever cable that wasn't allowing the kill to disengage... and the trimmer had a short in the kill switch. Obviously not the hot start problem we ve been talking about... but imo, these cheap kill switch designs should be looked at first as culprit when you have no spark....ive fixed 4 engines that were put on the curbs this summer alone with this issue.

 

[signcrafter]

Is it one of those engines where all you do is pull the rope to start? Automatic choke?

This. Briggs auto choke is known for exact issue.

 

[Wamsutta]

Yep. No primer or anything

Is there a linkage going from the choke plate on the carburetor to an area near the muffler?

 

[Pinemarten]

I would lean to a fuel issue. If you didn't have spark, it wouldn't run. If the coil was heating up and failing,
it would suddenly die like it was switched off. If it dies slowly like it is running out of gas........it probably is running out of gas for heat related reasons.

 

[rust in the eye]

Has it been down on power recently? Struggles in damp or tall grass?
Once more: a very dirty air filter can cause hot no start.
Doesn't sound like a spark issue but I'll bet a "fueling" issue. In this case too rich for a hot engine due to lack of airflow.
Takes 10 seconds to check.

 

[WWheeler]

This. Briggs auto choke is known for exact issue.

Definitely something to look into.

 

[jonesg]

it could be heat soak vaporizing the fuel in the bowl.
Choke and flood it to cool it down.

 

[Old Man Roger]

If the gas cap isn’t venting properly, it could cause a flooding situation when you turn the mower off. Pressure in the tank might over power the float valve?