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towmotor propane forklift continental engine vaporizer


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  #1  
Old 04-06-2015, 05:51:03 PM
dieter dieter is offline
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Default towmotor propane forklift continental engine vaporizer

I have a Towmotor propane forklift that quit running. I am new to propane. I can start the engine with starting fluid but itdies as soon as I quit feeding it starting fluid, therefore the problem is not electrical.

I rebuilt the carburetor (Bendix Zenith) but I don't know how to adjust the main valve at the bottom, but that is a minor problem, I think. I have learned that propane does not work like gasoline and it needs to be converted from liquid (solid) to vapor. I removed and disassembled what I think is a vaporizer from the engine where the upper cooling hose fits. There is one adjustment screw on that assembly and there is a water thermostat and one diaphragm. It appears simple. I am thinking that the liquid propane is allowed into the vaporizer by a solenoid valve when the ignition is actuated. I further think that the vaporizer is actually a nozzle that sprays the propane in the carburetor allowing it ignite the propane droplets by allowing the droplets to be mixed with outside air. After the engine starts and warm, the water from the radiator raises the temperature of the propane for better combustion.

AM I CORRRECT SO FAR?

How are the carburetor valves and the vaporizer to be adjusted?

Is there a repair kit available for the vaporizer or can one be purchased used; it seems so simple that I am nervous about its functioning. It would seem that if combustion did not occur immediately after turning the key that the engine would only have liquid propane and not enough air and the engine would flood. Again, I am not familiar with propane and have only used it for grilling or applying roofing materials. Is there a diagram available for the insides of the vaporizer? Other that a spring loaded valve inside the vaporizer, are there any moving parts?

I am assuming that this is a four cylinder flat head Continental engine as I can find not nameplates.

I will appreciate any help.

Thank You ,
Dieter Schmied
dieterschmied@gmail.com
Cincinnati, USA
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Old 04-06-2015, 06:45:54 PM
Ed Sparks Ed Sparks is offline
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Default Re: towmotor propane forklift continental engine vaporizer

the vaporizer takes liquid LP from the tank and heats it to make it into vapor which is injected into the carb and controlled by the demand regulator which is the diaphragm you saw.
What brand is your vaporizer?
Impco or garrettson are 2 of the more common brands. Rebuild kits are available for most at a reasonable cost.
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Old 04-06-2015, 06:57:50 PM
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Tim Litzenberger Tim Litzenberger is offline
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Default Re: towmotor propane forklift continental engine vaporizer

Make sure u have the proper tank. The propane must leave the tank as a liquid. Propane grill tanks, the fuel leaves the tank as vapor. If u are running a zenith carb, my experiance says u should be running a xenith vaporizer. The liquid propane enters the vaporizer, is heated by the hot coolant and leaves as a vapor.
My suggestion is if u suspect the vaporizer, buy a new one. U can google search zenith carb and vaporizer for instructions. ALSO propane trucks start very hard if at all below 30' degrees.

One last thing is u must have a good ignition system to ignite propane. If the spark is blue or violet great. Red or yellow spark will not ignite propane
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Old 04-06-2015, 08:20:26 PM
dieter dieter is offline
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Default Re: towmotor propane forklift continental engine vaporizer

Quote:
Originally Posted by Ed Sparks View Post
the vaporizer takes liquid LP from the tank and heats it to make it into vapor which is injected into the carb and controlled by the demand regulator which is the diaphragm you saw.
What brand is your vaporizer?
Impco or garrettson are 2 of the more common brands. Rebuild kits are available for most at a reasonable cost.
I do not have any way of knowing the make of the vaporizer. It appears to be original equipment there is only a casting number. The solenoid does have a label: Crown. But the solenoid is attached but is an electric component that is either open or closed.

As to heating the propane, this vaporizer would have to come to near operating temperature before it could heat anything. It contains a typical automobile engine thermostat and is essentially a heat exchanger when the engine reaches near operating temperature.

---------- Post added at 08:20 PM ---------- Previous post was at 08:02 PM ----------

Quote:
Originally Posted by Tim Litzenberger View Post
Make sure u have the proper tank. The propane must leave the tank as a liquid. Propane grill tanks, the fuel leaves the tank as vapor. If u are running a zenith carb, my experiance says u should be running a xenith vaporizer. The liquid propane enters the vaporizer, is heated by the hot coolant and leaves as a vapor.
My suggestion is if u suspect the vaporizer, buy a new one. U can google search zenith carb and vaporizer for instructions. ALSO propane trucks start very hard if at all below 30' degrees.

One last thing is u must have a good ignition system to ignite propane. If the spark is blue or violet great. Red or yellow spark will not ignite propane
I have a tank from another forklift.
I can see now what the effect of temperature would have on the propane engine; the forklift is in an unheated building. I cannot see the present vaporizer being very effective at heating the propane until the engine reached near operating temperature. This is an old forklift and I now suspect that one would have to baby the engine until it actually got warm by manipulating the manual choke.

I am now thinking that this forklift might not be worth the trouble. It steers hard and the design might be just too old.

What would you think of preheating the air going into the carburetor until it gets to temperature? I don't use the forklift very often. Conversion to gasoline, if possible, would be expensive, I think.

I would appreciate your comments as to alternatives.
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Old 04-06-2015, 08:46:14 PM
akuna akuna is offline
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Default Re: towmotor propane forklift continental engine vaporizer

Converting to gas may not be that hard. Need to know what engine you have and go looking for a carb. Electric fuel pump may be the best.

I bet you could sell the propane stuff and end up even or maybe ahead.

Don't forget to buy ethanol free gas.
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Old 04-07-2015, 09:45:27 AM
dieter dieter is offline
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Default Re: towmotor propane forklift continental engine vaporizer

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Originally Posted by akuna View Post
Converting to gas may not be that hard. Need to know what engine you have and go looking for a carb. Electric fuel pump may be the best.

I bet you could sell the propane stuff and end up even or maybe ahead.

Don't forget to buy ethanol free gas.
I can only say that it is a Continental 4 cylinder flat head engine based on pictures that I have seen on this and similar sites. The carburetor is Bendix Zenith and use a Zenith K2944 repair kit, which appears to be very popular. I would sell the forklift or the needed parts and I am in Cincinnati.

As to the type of gasoline carburetor, I can only say that the carburetor mounts under the intake manifold and takes in air from a side horn (opening) through an air cleaner. As soon as I can cut out eight-screw through holes plus one main bore gasket, I will reassemble the vaporizer and give it another try now that I have received a partial education on this site. Because the forklift is housed in an unheated building, I need to make some changes.
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Old 04-07-2015, 12:59:21 PM
sqm1 sqm1 is offline
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Default Re: towmotor propane forklift continental engine vaporizer

As I remember from working on the the hot water running thru it keeps the propane from freezing up under high flow.The sol. stops the flow when key is off.an the big screw adust the pressure going thru the reg.
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Old 04-07-2015, 05:37:10 PM
dkamp dkamp is offline
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Default Re: towmotor propane forklift continental engine vaporizer

There's quite a bit more disinformation floating around about propane systems, than information.

The propane system WILL start and run just fine at very low temperatures, but yes, it needs a little time to warm up... not much. Thirty seconds or so will be sufficient to motor around, but the biggest issue you'll face on the forklift, is that your hydraulic fluid will be very, very thick, so it will stall the engine REGARDLESS of what fuel you're using.

The first thing NOT to do, is to attempt to take apart or adjust anything in the propane system... read, study, learn FIRST... then figure out exactly what you've got.

Propane systems of liquid withdrawl include the following components, in order:

Tank with liquid withdrawl tap, liquid connection fitting,
Fuel lockoff (electric or vacuum operated)
First stage regulator (tank pressure to mid-low pressure (2psi or 10psi)
Evaporator (converter) (expansion orfice and heat exchanger turns propane liquid into propane gas)
Demand regulator
Mixer or venturi.

I'm unable to write a book on it right now, but each one of these components is very simple in operation, and each device corresponds to similar fueling in a liquid fuel system- the only difference, is the state of the fuel. Like gasoline, liquid propane does not burn. Like gasoline, an engine fueled so heavily that all oxygen is displaced, will be 'flooded', hence, not run.

For general reference, a propane engine's 'reaction' to fuel mixture character is opposite of that noticed in gasoline... i.e., when adjusting fuel mixture of a propane engine, if it sounds rich, it's lean... if it sounds lean, it's rich.

Adjusting or improperly assembling ANY of the system, particularly the primary regulator, fuel lockoff, or demand regulator, can result in a fuel system that flows fuel when the engine is not running... hence, flooding the engine, and the area within it resides, with fuel vapors... just like a gasoline engine, and just like gasoline, will blow you to h3!! if a source of ignition is available.

Read FIRST. Keep tools in bag.
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Old 04-07-2015, 06:48:11 PM
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FWurth FWurth is offline
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Default Re: towmotor propane forklift continental engine vaporizer

A stupid question here, no one has asked the simple question is the tank empty? Is any fuel even getting to the vaporizer? There should be a line filter/ screen in the supply line that could be clogged. Check the simple stuff first.

Last edited by FWurth; 04-07-2015 at 07:03:03 PM.
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Old 04-08-2015, 08:33:21 AM
dkamp dkamp is offline
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Default Re: towmotor propane forklift continental engine vaporizer

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Originally Posted by dieter View Post
As to heating the propane, this vaporizer would have to come to near operating temperature before it could heat anything. It contains a typical automobile engine thermostat and is essentially a heat exchanger when the engine reaches near operating temperature....I cannot see the present vaporizer being very effective at heating the propane until the engine reached near operating temperature.
The vaporizer works on a very basic principle... that propane, at ambient pressure and any temperature above -44F or so, boils. At higher ambient pressure, the boiling point is higher.

Let's use a ordinary winter day as an example... 25F or so, the propane tank will indicate 50psi. There is gaseous propane in the top of the tank, and liquid in the bottom. If you remove some of the liquid, and there's ANY liquid left in the tank, the fuel in the tank will evaporate and expand until pressure returns to 50F.

The liquid withdrawn through the liquid tap is also at 50psi, until it reaches the first regulation stage. In a liquid withdrawl system, that first stage is IN the evaporator. At the inlet is a fuel-lock off valve (either vacuum, or electric solenoid) that shuts off fuel flow, followed by an orfice where liquid passes through with line pressure on one side, and an expansion area on the other. As fuel passes through the orfice, the transition of pressure causes the fuel to 'flash' to gaseous state.

In comparison, a steam engine- you have a boiler with water that is well above ambient boiling point... say, 300f, the boiler pressure will be 50psi. When you release water from the bottom of the boiler, it sprays out as water, but never reaches the ground, because it makes the transition to steam immediately.

The evaporator is little more than a cavity to allow the expansion, and propane WILL expand and evaporate in that cavity. The heat exchanger around the cavity isn't required to make it happen, it's only there to improve the speed of evaporation at high flow rates. Low power installations frequently do not have any cooling lines connected to the evaporator, and in larger air-cooled setups, the evaporator is just mounted on a bracket on the side of the engine.

There aren't many things that can go wrong with the evaporator, it has no moving parts, just an orfice. If the evaporator includes a fuel lockoff and a regulator, those components would be more likely suspect, however, the regulator and fuel lockoff function (sometimes integrated) is non-adjustable, and simple enough in operation that only two things typically cause a failure- first is contamination of fuel, and second, is improper disassembly and reassembly.

---------- Post added at 07:27 AM ---------- Previous post was at 07:13 AM ----------

The next component in the system is a 'demand regulator'. The demand regulator senses fuel demand flow from the mixer or venturi spud, in the form of slight vacuum... and as the vacuum signal of demand changes, the demand regulator flows fuel in proportion to that demand.

It is the equivalent of a float bowl, fuel level, and throat vacuum of a liquid carbeurator, but without all the dependant components. The demand regulator typically has no more than four moving parts, typically a diaphram, a spring, a lever, and a valve tip. Gaseous propane comes in through the valve tip, and is allowed into the vacuum signal stream based on pressure.

The demand regulator is frequently referred to as a 'zero governor' or 'negative pressure regulator', because it does exactly what any OTHER pressure reguator does... it takes a high pressure, and limits it to a lower pressure, with the only difference being that it's outlet pressure is LOWER than ambient pressure... that is, whatever vacuum level the venturi's signal pressure happens to be.

Next component is the mixer or venturi spud. Air flowing into the engine, flows through a venturi, where velocity increases at the convergent zone, and decreases at the divergent zone. Because of the change in velocity occuring, the pressure at the divergent zone is LOWER than ambient temperature. In a gasoline engine, this point is where the main jet's discharge point is... and this pressure differential (between ambient pressure in the float bowl, and lower pressure in the venturi) causes fuel demand to withdraw liquid form the bowl like a child sipping on a straw. As the carbeurator throttle opens, lower pressure at the venturi causes more fuel demand.

On a propane system, the exact same thing happens, with the only difference being that the fuel is already evaporated.

The catch here is, that when an automobile carb is not being demanded fuel, the fuel stays in the bowl, as a liquid (in theory). When a gaseous fuel system is shut down, the demand regulator SHOULD stop flowing fuel... because there's no demand, right?

Wrong. The demand regulator is a very sensitive device- it has to respond to slight changes in signal pressure to know when, and how much fuel to flow. When someone noodles with the demand regulator, one of two failure modes occur- first,is that it never flows fuel, and the engine refuses to start. Second, is that it 'leaks' fuel (like a stuck float valve on a carb bowl), and displaces the oxygen from the intake manifold, causing a 'no start'... and worse, continues to flood the area with gaseous propane, looking for a source of ignition.

Another common failure mode of a liquid propane system, is having the demand regulator lock shut tightly, allowing pressure to build on it's inlet side, AND having the fuel lockoff 'leak' liquid into the evaporator when there's no fuel demand, eventually flooding the line between evap and demand reg. It's a liquid, under pressure, and once ambient temperature rises, pressure in that line will rise as well, and when pressure rises, it has to go SOMEWHERE.

It's not complicated equipment, but it's not equipment that should be haphazardly worked on without having proper understanding of the principles.

---------- Post added at 07:33 AM ---------- Previous post was at 07:27 AM ----------

There are typically only two adjustments on a propane fuel engine. First is the demand regulator's bias or sensitivity adjustment... this not only affects the amount of fuel flowed based on demand signal from the venturi, it ALSO affects the demand regulator's ability to cut off fuel in a non-running engine.

The second, is the demand valve on the venturi. It's typically a long, fine-threaded bolt with a locknut, and it adjusts the flow in a quasi-similar fashion to the high-speed jet on a liquid carbeurator... but what it's really doing, is tailoring the maximum flow volume that appears when the engine is at full demand.

Again, most people make the mistake of diving in and noodling with the adjustments, with no idea of how and why it works, and after making one adjustment, have no idea how to get it back into proper setting. In order to get it back in proper setting, one must either obtain or make a manometer, and get the demand regulator and evaporator set back to design settings, and then adjust the demand valve.

And since propane has different burning qualities, spark plugs must be gapped a little closer, frequently a different heat range (depending on the engine) and they like really powerful ignition- if it's not a nasty blue spark, find more spark energy, it'll want it.
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Old 04-08-2015, 08:51:54 AM
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Default Re: towmotor propane forklift continental engine vaporizer

Tank is 1/2 full. I think that I better understand the lpg now. Thanks
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Old 04-08-2015, 10:32:14 AM
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Default Re: towmotor propane forklift continental engine vaporizer

The reason I ask that question is that the shut off valve on those tanks aren't all the same as I recall. I think that the newer tanks have a safety valve that automatically shuts off if the line is severed, the two types likely won't interchange. So if you try to use an old tank on a new system it won't work and likewise if the you try a new tank on an old system. Most have been changed over but not all. It's been a while since I had anything to do with them but that's what I recall.
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Old 04-08-2015, 11:33:53 AM
dkamp dkamp is offline
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Default Re: towmotor propane forklift continental engine vaporizer

Motor fuel tanks are different from domestic (heat/gas grill) tanks, and in both motor fuel and domestic tanks, there are safety features whose designs have changed over time... some ideas being much better than others, so it IS possible that the tank has some feature that isn't compatible, or is downright not working... and some 'safety concepts' are actually more dangerous than not. Safety features often lead to complacency and ignorance which becomes a much greater hazard.

SOME tank systems have 'excess flow protection' in them... it's a valve that senses fuel flow velocity, and at a point above a certain velocity, the valve will shuttle to a lock-out position. This MAY be an issue... so worth investigation.

Another note- Propane and gasoline are really not much different in one respect- they're both liquids at some point. Consider that if it's -50F ambient temperature, you can dip a coffee cup of liquid propane right out of a bucket, funnel it into the bowl of a carbeurator, and start the engine like it's gasoline. If it's +210F outside, you'll need to keep that gasoline in an enclosed pressure vessel and pipe it through a propane system. It's all a matter of relative perspective.
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Old 04-08-2015, 12:42:08 PM
2wheelBob 2wheelBob is offline
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Default Re: towmotor propane forklift continental engine vaporizer

Dieter,

Any chance you can post a pic of your vaporizer and carburetor? It would be helpful to see what system your lift has.

From your original description I think I could rule out an "Impco" system. When you say the vaporizer was attached to the thermostat housing it makes me think you have a "J&S" style system (odd, most Towmotors in my neck of the woods ran Century or Beam systems)

* Double check your Rego female coupling, on your lifts gas hose, for a displaced tank o-ring..sometimes the tank's male Rego o-ring will stay attached to the female when you unscrew it from the tank, when you attach it to the next tank no gas will flow as the double o-ring prevents full engagement of both halves of the coupler.
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Old 04-09-2015, 10:17:38 AM
dieter dieter is offline
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Default Re: towmotor propane forklift continental engine vaporizer

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Originally Posted by 2wheelBob View Post
Dieter,

Any chance you can post a pic of your vaporizer and carburetor? It would be helpful to see what system your lift has.

From your original description I think I could rule out an "Impco" system. When you say the vaporizer was attached to the thermostat housing it makes me think you have a "J&S" style system (odd, most Towmotors in my neck of the woods ran Century or Beam systems)

* Double check your Rego female coupling, on your lifts gas hose, for a displaced tank o-ring..sometimes the tank's male Rego o-ring will stay attached to the female when you unscrew it from the tank, when you attach it to the next tank no gas will flow as the double o-ring prevents full engagement of both halves of the coupler.
I am not near the forklift right now.
It is mounted on the thermostat housing which has the word "zenith" on the casting. The actual mechanism/heat exchanger is aluminum where a solenoid valve (Clark brand) is attached to the inlet. It has a large threaded screw with lock nut which adjusts and exerts pressure on a spring which applies pressure to a diaphragm which opens or closes a light-spring loaded "ROUND/FLAPPERLIKE" valve, which allows the liquid/gas to go out through to the carburetor. I have seen a picture on someone's website for a repair kit with a Caterpillar brand name; it gave no part name. The only thing that was damaged was an eight screwhole gasket and I did not want to spend eighty dollars for a gasket; the diaphragm was tight. Other than the input solenoid valve, there is no electric to the "vaporizer".

Is this recognizable?
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Old 05-25-2016, 07:31:14 AM
WillysOverland WillysOverland is offline
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Default Re: towmotor propane forklift continental engine vaporizer

e bay sells impco vaporizers cheap. I needed one and when I took the old one off the info was on the side facing the machine where I couldn't see it. my machine starts right up and runs perfect now. well worth the 100 bucks. I spent more time thinking about fixing it then it took to fix it.
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