Heat soak

[rogue60]

Back when I was in the Army and flying OH-13s (1967) with a heap of instrument accessories for 'instrument flight school' the turbo assist was 30 psi of boost for 30 seconds on a hooded take-off.

The fuel was PURPLE, it was 115-145 octane (lean to rich mixture). I've never seen that fuel again. I doubt my race bike would have needed that octane, but then in a pinch it might have been nice to have during the summer running up a hot sand wash.

I've never had problems with fuel only the last couple of years in 2T's.
Remember our old unleaded was purple? that was the last good fuel we could get now it's this colorless like thinners crap put a few inches in an open container out in the hot sun it will evaporate to nothing in a few minutes I don't remember fuel of old doing that?

 

[P.M.P.]

We could pay @Red97 to leave a saw in a car all day when it’s 90 out and then make a pull on his dyno.

Does he own a husky?

 

[huskyboy]

Interesting video, thought it related to the subject a bit.

 

[rogue60]

Interesting video, thought it related to the subject a bit.

Interesting so they can blend a fuel that does none of this squirting i.e. Avgas for example?
But they make use sheep use this squirting gas in ope and call it operator error i.e. he's not had sufficient training to open a gas cap if squirting does occur?...
Hmm wish I was rich and could make the rules up along the way to cover my ass from any liability in life lol

 

[av8or3]

I think Avgas or any fuel will squirt out the cap when it’s hot. I think that’s a build up of pressure in the tank that caused it to splash all over when the caps opened hot. I recently shook up a 3/4 full 5 gal can of mix before dispensing and without thinking pulled back on the lid as I leaned over to pour. OMG ! Gas everywhere! Was in panic mode for awhile while I cleaned it up. If a chainsaw does that (never happened to me) I’d run that sucker dry before chancing that , in the woods especially with a hot saw and all.

 

[rogue60]

I think Avgas or any fuel will squirt out the cap when it’s hot. I think that’s a build up of pressure in the tank that caused it to splash all over when the caps opened hot. I recently shook up a 3/4 full 5 gal can of mix before dispensing and without thinking pulled back on the lid as I leaned over to pour. OMG ! Gas everywhere! Was in panic mode for awhile while I cleaned it up. If a chainsaw does that (never happened to me) I’d run that sucker dry before chancing that , in the woods especially with a hot saw and all.

Through my un scientific testing in 40c 100f summer heat on this matter. The Avgas I have access to doesn't boil pressurise or do anything crazy like pump fuel it's quite boring actually sits in the tank like a boring old none volatile liquid..
IDK what is going on or do I have any anwsers am just conveying my experiences with my limited testing on this.

 

[Terry Syd]

My fully vented tanks don't geyser fuel when I open the tank, all the pressure has long since been vented. Of course, the EPA would object to having fully vented tanks.

 

[Wilhelm]

I helped my health impacted neighbor process his firewood yesterday.
He had an impressive workforce of logger buddies of his and his employee, 3-5 saws and 2 fairly big hydraulic tractor driven vertical splitters.

I drove over with my car, took the following saws with me, all of which I fired up at home without issues before placing them in my cars trunk.
Makita XA5000, Dolmar MMWS6100, Dolmar PS-7310, Dolmar PS-7900 & 36" B&C, Dolmar PS-9010
My PS-7900 took a ride on the back seat due to the 36" B&C, the others were in the cars trunk.

The first saws to come out were my PS-7900 & MMWS6100, they fired up fine.
The PS-7900 was on noodling duty, I ran her out of fuel and by the time I walked to my car and refueld her she was vapor locked.
I opened my cars trunk, got hit by an insane amount of heat coming out of it, and grabbed my PS-7310.
I tried starting her up but she didn't make a single sound of coming to life - and she didn't for the remainder of the day.
I barely restarted my PS-7900 pouring fuel directly into the cylinder, twice.
She vapor locked a second time too even though I kept her run idle between noodling cuts.

Summary:
- PS-7900 , vapor locked twice, got run hard and long
- PS-7310 , vapor locked just from sitting in the hot car trunk, no go all day
- XS5000 , MMWS6100 , PS-9010 , started fine when needed , all three did some bucking , the XS5000 had some noodling action too

Identical transporting and storing conditions for all saws, same fuel mix, hot and humid day as it rained the previous day.

My Dolmar PS-7900 wearing 36" B&C setup noodling 40" beech and oak rounds was the star of the show.
The loggers said "they have never seen anything like it"!
They run 661's and 462's with 18" bars at work, and yeah they are hamfisted with their equipment.

 

[huskyboy]

 

[Philbert]

The PS-7900 was on noodling duty, I ran her out of fuel and by the time I walked to my car and refueld her she was vapor locked.
I opened my cars trunk, got hit by an insane amount of heat coming out of it, and grabbed my PS-7310.
I tried starting her up but she didn't make a single sound of coming to life - and she didn't for the remainder of the day.

No way to clear the vapor lock? The carb on these saws is pretty small.
- compressed air?
- dry ice?
- 'real' ice from a beverage cooler?
- cooler fuel from a container sitting in the shade?

Etc.

Philbert

 

[rogue60]

No way to clear the vapor lock? The carb on these saws is pretty small.
- compressed air?
- dry ice?
- 'real' ice from a beverage cooler?
- cooler fuel from a container sitting in the shade?

Etc.

Philbert

All of the above would probably work and get a saw running again. but 5min of run time the saw will be hot and back to vaper lock.
I have my own solution that works but as time goes on and more people click on it's the fuel of today and nothing to do with ope the more different kinds fuels will be tested and more solutions as to what fuel works if it's warm out.
It's easy to test when a saw vaper locks dump that tank of fuel fill with test fuel say like caned fuel? If problem goes away in same continued conditions there is the answer.

 

[Wilhelm]

No way to clear the vapor lock? The carb on these saws is pretty small.
- compressed air?
- dry ice?
- 'real' ice from a beverage cooler?
- cooler fuel from a container sitting in the shade?

Etc.

Philbert

Compressed air - not an option in the field, especially if You don't own a compressor, also hot air does not really cool much

Dry and/or real ice - in the summer heat I'd rather dunk my head into a bucket full of it than waste it trying to get my saws started

Cooler fuel - again, in the field when it is 40℃ in the shade not easy to accomplish

Grab another saw was my solution, unlucky for me that backup saw was vapor locked from sitting in the cars trunk too.

The first vapor lock on my PS-7900 I tried mitigating with dozens of pulls, under choke, half throttle, WOT - no deal.
I pulled the plug, which I generally hate and avoid to do as not to wear the threads.
The plug was bone dry.
I poured a fair sip of fuel directly into the plug hole and pulled the starter cord full length to "spread" the fuel.
Bolted down the spark plug and pulled the starter rope, engine came to life sputtering and smoking, died as I gave it a throttle blip.
Removed the plug again which this time was dripping wet.
I dried the plug and repeated the above, saw again came to life and this time I was careful blipping the throttle.
Saw sputtered and smoked a lot but this time stayed running.

On the second vapor lock I force started the saw with multiple pulls holding the throttle WOT.

I think there is some truth to the suggestions that the fuels are at fault.
I am noticing vapor lock issues only a few years back, and ONLY in the summer.
My saws don't appear to vapor lock in winter, spring, autumn.

 

[huskyboy]

Compressed air - not an option in the field, especially if You don't own a compressor, also hot air does not really cool much

Dry and/or real ice - in the summer heat I'd rather dunk my head into a bucket full of it than waste it trying to get my saws started

Cooler fuel - again, in the field when it is 40℃ in the shade not easy to accomplish

Grab another saw was my solution, unlucky for me that backup saw was vapor locked from sitting in the cars trunk too.

The first vapor lock on my PS-7900 I tried mitigating with dozens of pulls, under choke, half throttle, WOT - no deal.
I pulled the plug, which I generally hate and avoid to do as not to wear the threads.
The plug was bone dry.
I poured a fair sip of fuel directly into the plug hole and pulled the starter cord full length to "spread" the fuel.
Bolted down the spark plug and pulled the starter rope, engine came to life sputtering and smoking, died as I gave it a throttle blip.
Removed the plug again which this time was dripping wet.
I dried the plug and repeated the above, saw again came to life and this time I was careful blipping the throttle.
Saw sputtered and smoked a lot but this time stayed running.

On the second vapor lock I force started the saw with multiple pulls holding the throttle WOT.

I think there is some truth to the suggestions that the fuels are at fault.
I am noticing vapor lock issues only a few years back, and ONLY in the summer.
My saws don't appear to vapor lock in winter, spring, autumn.

I’ve never had a problem with vapor lock with dolkitas. They are actually pretty resistant to it compared to a 562xp. Gutting the muffler on saws and leaving the gas can in a cool place when cutting is a good idea.

 

[Bilge Rat]

The lawn guys see vapor lock/ hard start here in the summer.
Weedeaters, blowers etc have problems starting in the summer heat for the last few years.

 

[Philbert]

Would a saw purge valve help with vapor lock?

Just asking these questions, since I have never experienced this type of problem, beyond needing to open the fuel tank valve to release pressure or vacuum, fill a half empty tank, etc.

Thanks.

Philbert

 

[rogue60]

Would a saw purge valve help with vapor lock?

Just asking these questions, since I have never experienced this type of problem, beyond needing to open the fuel tank valve to release pressure or vacuum, fill a half empty tank, etc.

Thanks.

Philbert

Watch the vid huskyboy put up looks like it's affecting old cars with low fuel pressure boiling in the fuel line on it's way to the carb. they came up with a mechanical solution in the way of high fuel pressure rasing the boiling point of the fuel and return to keep fuel moving to overcome these rubbish fuels bit hard to do in a saw.
All vaper lock is is the fuel boiling creating air in fuel lines.
It's starting to become a problem thanks to whatever it is they have done to pump fuel now days.
Vaper lock is not a problem until it happens to you using ope and you can't finish the job at hand.

 

[Philbert]

I watched the video. I ain't putting that thing in my chainsaws! I will stick to the battery saws first (although, Li-Ion batteries have upper temperature limits too).

Would a purge valve get more liquid through the carb, even when hot?

Philbert

 

[huskyboy]

Would a purge valve get more liquid through the carb, even when hot?

Yes... at least until you begin to boil/vaporize the gas in the tank itself then your back to square one. Lol

 

[huskyboy]

I think attempting to use better fuel and try to leave the saw/fuel in the shade when not using them (if possible) is a start. Letting the saws idle down before shutting them off helps too. A muffler mod lets heat out as well. You will see ported saws vapor lock before a stock one with a muffler mod does... the added compression makes them run hotter.

 

[Philbert]

Those Ninja Foodi pressure cooker things make good use of that low heat pressure. Maybe we need a Stirling heat engine chainsaw, or a turbocharger, or something to make use of that excess heat and vapor.

I'll work on it this week.

Philbert