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LP forklift hard to start?
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Mike SE IL
Posted 2/8/2010 08:46 (#1064019 - in reply to #1063977)
Subject: RE: Are weather problems related.....

West Union, Illinois

farmerbk - does cold weather make the regulator problem worse? There are three forklifts in the neighborhood that run on propane, and in warm/hot weather run pretty well, but are hard or no start in cold weather and run fair if started until warm.
I don't want to be known as the LP motor fuel guy because all I know is from my pretty much limited experience.  I'm going to say the best answer is "Yes,  sometimes".  Cold weather and propane are a poor combination.

I had a route customer with an old Ford pickup on LP that would start at -20 setting outside with no heat. He was an exception.  Charlie taught me (back to Charlie again) if it got much below freezing to plug it in and always let the engine warm up a little before trying to drive it.

I just realized my first experience with LP as a motor fuel. My best friend in High School's dad managed a local LP plant.  I remember pulling in his driveway one late fall day to see Bud pouring hot water on something under his truck's hood. He said he knew he should have let the #$%^ thing warm up first.  Bud lived across the street half a block from the office.  He was only crossing the highway so he didn't let it warm up first.

3 basic facts you need to know to understand the problem

1)Liquid propane does not burn. VAPORIZED propane burns. For reasons we won't dive into here propane is taken from the fuel tank in liquid state.

2) When a liquid held under pressure above its boiling point is released to atmospheric pressure it boils and it makes the temperature its boiling point.  If you use a pressure cooker to heat water, when it escapes as steam it is 212F.  The boiling point of propane is -44F.  So when it changes from liquid to vapor it is -44.

3) Firefighting 101 teaches us fire requires heat, oxygen, and fuel. 

How is all that relevant? LP engines run on vapor and water cooled engines generally use a coolant warmed vaporizer to get the propane warm enough it is a vapor state.  When it is cold the propane does not vaporize well.  Until the water in the vaporizer is warm your engine's fuel supply is lousy.  It may have droplets of liquid that do not burn well and when they turn to vapor rob heat out of the combustion chamber.   This liquid propane is robbing the combustion process of 2 of the 3 requirements for a fire.  No fire, engine no run.

Rebuilding a vaporizer may help that.  As the vaporizer is used it builds up "crud" inside.  The crud keeps it from working like it should.  Back to "Charlie said" the crud out is the most important part of a vaporizer rebuild.  So if your forklift is not running well until it is warm you might try rebuilding or replacing the vaporizer.

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