Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Why is it Vapour Locking?


  • Please log in to reply
19 replies to this topic

#1 New.Canadian.DB.Owner OFFLINE  

New.Canadian.DB.Owner
  • Senior Member
  • Contributor
  • Member No: 10178
  • 2,224 Thanks
  • 1,451 posts
  • Location: Trenton, Ontario, Canada

Posted July 13, 2015 - 02:37 PM

I have a generator with a Tecumseh engine.  It keeps vapour locking on me.  I purge the fuel line before starting, but slowly bubbles start to form & work their way up to the shutoff valve, but they won't go past it into the tank.  Within 15 minutes, the fuel line is full of fuel vapour (or air) & the engine stalls. The gas cap works & it does it whether the cap is on or off.  I have installed a piece of garden hose as a temporary heat shield, but that hasn't helped.  Any ideas on where to go from here?

 

 

1.jpg 2.jpg 3.jpg 4.jpg 5.jpg 6.jpg 7.jpg


  • MH81, hamman, boyscout862 and 1 other said thanks

#2 propane1 ONLINE  

propane1
  • Senior Member
  • Member No: 54307
  • 6,110 Thanks
  • 3,202 posts
  • Location: Charlottetown, Prince Edward Island, Canada

Posted July 13, 2015 - 02:52 PM

Would the carb float bowl vent be blocked. Float bowl needs air to operate. When the needle opens to let gas in, the air in the bowl is going back up to the tank, to allow gas into the bowl, until needle shuts it off again. If the bowl was vented it would allow air out of the bowl, to allow gas in. Just a guess,  Noel


  • MH81, Alc, hamman and 1 other said thanks

#3 DougT ONLINE  

DougT

    Dog Approved

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 584
  • 5,728 Thanks
  • 4,286 posts
  • Location: north central Ohio

Posted July 13, 2015 - 03:09 PM

Have you pulled the shut off valve out of the tank and made sure it isn't partially clogged?


  • MH81, hamman, boyscout862 and 1 other said thanks

#4 boyscout862 ONLINE  

boyscout862
  • Senior Member
  • Member No: 8923
  • 9,795 Thanks
  • 7,541 posts
  • Location: N.E. Connecticut

Posted July 13, 2015 - 03:34 PM

First, great pics! I agree with DougT that I suspect that the valve is partially plugged. Some of them have a screen to catch junk. I like the old sediment bowl under the tank so that you can see any dirt or water. Good Luck, Rick

 

My wife's MTD kept dying on Saturday because the fuel line collapsed.


Edited by boyscout862, July 13, 2015 - 03:36 PM.

  • hamman and New.Canadian.DB.Owner have said thanks

#5 LilysDad ONLINE  

LilysDad

    Cat Lover

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 10443
  • 9,652 Thanks
  • 7,677 posts
  • Location: N. Illinois, DeKalb County

Posted July 13, 2015 - 03:40 PM

In the very first picture, it almost looks like the bend in the hose is higher than the barb on the inlet. Do you have one that points down?


  • MH81, hamman and New.Canadian.DB.Owner have said thanks

#6 hamman ONLINE  

hamman

    Homelite Owner Extraordinaire

  • Senior Member
  • Contributor
  • Member No: 1733
  • 5,629 Thanks
  • 2,583 posts
  • Location: Michigan

Posted July 13, 2015 - 04:24 PM

Just redid the fuel line on a snowblower that had collapsed inside.  Fuel filter going right way?  Just a WAG ! Good luck.                                           Roger


  • boyscout862, New.Canadian.DB.Owner and propane1 have said thanks

#7 dodge trucker ONLINE  

dodge trucker
  • Senior Member
  • Member No: 19314
  • 1,440 Thanks
  • 1,897 posts
  • Location: kankakee

Posted July 13, 2015 - 05:16 PM

what is "vapour"  I know what "vapor" is....


  • New.Canadian.DB.Owner said thank you

#8 chieffan ONLINE  

chieffan
  • Senior Member
  • Contributor
  • Member No: 62695
  • 6,157 Thanks
  • 4,503 posts
  • Location: SW Iowa

Posted July 13, 2015 - 05:56 PM

what is "vapour"  I know what "vapor" is....


Same thing, only spelled different. Is this English class or what???
  • New.Canadian.DB.Owner and propane1 have said thanks

#9 New.Canadian.DB.Owner OFFLINE  

New.Canadian.DB.Owner
  • Senior Member
  • Contributor
  • Member No: 10178
  • 2,224 Thanks
  • 1,451 posts
  • Location: Trenton, Ontario, Canada

Posted July 13, 2015 - 05:57 PM

Would the carb float bowl vent be blocked. Float bowl needs air to operate. When the needle opens to let gas in, the air in the bowl is going back up to the tank, to allow gas into the bowl, until needle shuts it off again. If the bowl was vented it would allow air out of the bowl, to allow gas in. Just a guess,  Noel

Not sure, but the carb is clean externally.  I would think that if the atmospheric vent was plugged, there would not be any air getting into the carb as the fuel left to be pushed up the fuel line when the float rose.



#10 New.Canadian.DB.Owner OFFLINE  

New.Canadian.DB.Owner
  • Senior Member
  • Contributor
  • Member No: 10178
  • 2,224 Thanks
  • 1,451 posts
  • Location: Trenton, Ontario, Canada

Posted July 13, 2015 - 05:57 PM

Have you pulled the shut off valve out of the tank and made sure it isn't partially clogged?

 

I removed the fuel line & blew air back through the shutoff.  No change.

 

In the very first picture, it almost looks like the bend in the hose is higher than the barb on the inlet. Do you have one that points down?

 

The fuel line has a downward slope over the entire length.  Not sure which inlet you mean, but I twisted the carb inlet a couple of degrees to get it sitting flat or slightly downhill as the fuel runs.  I can't figure out how to get the shut off valve out of the rubber fitting at the tank.  

 

Just redid the fuel line on a snowblower that had collapsed inside.  Fuel filter going right way?  Just a WAG ! Good luck.                                           Roger

 

Fuel filter is just one of that has a screen mesh in the centre.  I don't think it has a right or wrong way.  I did try a paper filter style filter, installed correctly, but it did the same thing.

 

what is "vapour"  I know what "vapor" is....

 

Google it.


  • DougT, MH81, hamman and 1 other said thanks

#11 TimW OFFLINE  

TimW
  • Senior Member
  • -GTt Supporter-
  • Member No: 10778
  • 367 Thanks
  • 235 posts
  • Location: Kentucky

Posted July 13, 2015 - 06:21 PM

This might or might not be relevant, but I have dealt with 2 of the small generators with the Tecumseh, 8hp I think. of that style.  Both would just die after running for a few minutes.  I went thru the carbs several times.  I blamed vapor lock, I blamed the low oil shutdown.  I could not isolate anything.  I even ran a remote gravity fed fuel tank, made no difference.  Looking back on it, I wander if it could have an erratic valve problem, maybe sticking open.  If it turns out to not be vapor locking, please let me know what you found.  


  • New.Canadian.DB.Owner and propane1 have said thanks

#12 LilysDad ONLINE  

LilysDad

    Cat Lover

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 10443
  • 9,652 Thanks
  • 7,677 posts
  • Location: N. Illinois, DeKalb County

Posted July 13, 2015 - 06:26 PM

what is "vapour"  I know what "vapor" is....

Vapour is what they get in Ontario. In the rest of Canada and other English speaking countries, we get vapor.


  • New.Canadian.DB.Owner said thank you

#13 Gtractor ONLINE  

Gtractor

    The Tractor Hoarder

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 782
  • 6,624 Thanks
  • 3,917 posts
  • Location: Chillicothe, MO

Posted July 13, 2015 - 06:28 PM

Yeah,  its kinda like turning the soil with a plough.    :thumbs:


  • New.Canadian.DB.Owner and LilysDad have said thanks

#14 propane1 ONLINE  

propane1
  • Senior Member
  • Member No: 54307
  • 6,110 Thanks
  • 3,202 posts
  • Location: Charlottetown, Prince Edward Island, Canada

Posted July 13, 2015 - 06:35 PM

With the float bowl vent blocked, and the fuel fowling into the bowl, it would have to get air from some where to allow gas to run into the bowl ?? Just another thought and guess. Noel
  • New.Canadian.DB.Owner said thank you

#15 drbish ONLINE  

drbish

    Collecter

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 2544
  • 1,162 Thanks
  • 1,162 posts
  • Location: Mooresville,NC

Posted July 13, 2015 - 06:57 PM

This is on the MTD site about vapor lock

http://support.mtdpr...engine-stalling


  • MH81, Alc, New.Canadian.DB.Owner and 1 other said thanks




Top