PT-425 Vapor Lock?

   #1  

BigDaddyEureka

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I took delivery of a shiny new mower deck and tiller on Friday, so I was eager to get to chopping down the mess of weeds that had sprung up on a couple of acres of ground that will become an orchard next year. It was hot - about 90F ambient - and after 4 hours of fun (and on the second tank of fuel) and nearly finished with the work, the engine just....faded to a stop. Not a violent thing at all, just the mechanical equivalent of the hard working mule sitting down and saying "nope, we're done for a bit." After a 15 minute water break I went back, took a minute to shake out the precleaner foam (it was filthy as expected), and it fired right up no problems at all.

Has anyone else had this happen with the PT-425 with the Kohler Command Pro 750 engine? I think what happened was simple vapor lock from the heat, but maybe there's more to it? Otherwise, everything seems fine...
 
   #2  

Goose1776

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Massey 2706e
Would be interested in the replies you get…
But that is what it sounds like.
 
   #3  

ponytug

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Power Trac PT1445
Sure sounds like vapor lock to me. Do you have any clear view of the fuel, e.g. a plastic fuel prefilter?

Having dealt with vapor lock in the past, I'm kinda "once burned, twice shy", and inclined to reroute and insulate fuel hoses at the first signs of it, as it never gets better. Given the time of year, you may not see it again for awhile though...YMMV

All the best,

Peter
 
  
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#4  
OP
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BigDaddyEureka

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Hmm...the current factory fuel filter is opaque, but next time I'll use a clear one so I can see what's going on. Good idea Peter!

I'll also take a look at the fuel line routing to see if there's some insulation opportunity too.
 
   #5  

ponytug

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Hmm...the current factory fuel filter is opaque, but next time I'll use a clear one so I can see what's going on. Good idea Peter!

I'll also take a look at the fuel line routing to see if there's some insulation opportunity too.
They make aluminized foam and thermal sleeves with velcro that work pretty well.

The other thing to check for in PTs is debris left in the fuel tank or fuel line. A few (more than a few?) people have found plastic shavings at the fuel outlet or in the fuel line that cause significant restrictions and make vapor lock much more likely to happen. I remember someone had photos of a nearly color matching shaving that was almost fully blocking the outlet.

All the best,

Peter
 
   #6  

cqaigy2

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They make aluminized foam and thermal sleeves with velcro that work pretty well.

The other thing to check for in PTs is debris left in the fuel tank or fuel line. A few (more than a few?) people have found plastic shavings at the fuel outlet or in the fuel line that cause significant restrictions and make vapor lock much more likely to happen. I remember someone had photos of a nearly color matching shaving that was almost fully blocking the outlet.

All the best,

Peter
This one right here, debris in the fuel tank. After rerouting, insulating fuel line, replacing fuel pump, the one thing left was the white debris in the fuel tank. Once i got all the crap out of the tank, it was smooth sailing. The stuff in the fuel tank was very hard for me to make out. I just kinda took it on faith, and pulled the tank, and sprayed water soap inside, rinsed and repeat rinse. Dried that tank and i accidentally got the light just right, and could make out some stuff in the neck of the connector at the bottom of the tank.
 
   #7  

ponytug

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@cqaigy2 Thanks! Sorry, I remembered your saga, but who was buried in the fog of my memory.

I have a curl of black plastic caught in my prefilter that refuses to come out. (Backflow, air, shaking haven't cleared it.) It isn't clear where it came from, but since it isn't blocking anything, I have left it. So far the prefilter remains spotless, so I haven't changed it. I do think of your saga, whenever I glance at the prefilter.

All the best,

Peter
 
 
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