It's common for a rebuild kit from Walbro, or most any other carb company to fit more than one carb.
It's also common, especially lately for a kit to have more than one type of diaphram in it.
I recently bought a kit that had both the neoprene(black) pump diaphram, as well as the acetate(blue) pump diaphram in it.

Per the attached picture, it seems that the blue film diaphram isn't a very good pumper.
What bothers me a little is the fact that some kits are not adding the black parts in the kits anymore.

Question is ---> Does anyone have experience using the blue pump diaphram, or blue surge diaphram in an aircraft application?
I am also trying to find out exactly what a surge diaphram really does?
The Walbro WT series manual shows one in the exploded view, but my Wt-201B didn't have one when it came apart from the factory.

Thanks
Bob

I have a couple WT-201 carbs and have rebuilt them using the rubber and the acetate diaphragms. I have had no real issues with either. The only thing I see is that the rubber ones will dry out in time.

Did any of yours use the surge diaphram shown in the manual?

The manual page you speak of shows all possible parts that may be on or in a particular carb. I would look closer at the diagram, you may see that the gasket or diaphragm you see may be for a carb with a primer bulb. Any carb I have worked on that doesn't have a primer bulb only has 2 gaskets and diaphragms.

it protects against, or uses, surges in some carb types?
For Y'all who wonder what the *** the surge diaphragm is: It is tha part inserted between the fuel pump side cover, and the pump diaphragm. I have never seen it in airplane engine carbs, but it is listed as part #33 in the Walbro WT manual. It must have some use in some carbs, or Walbro would not list it.

Some of us who are stuck in a area where you can't get gas unless it's mixed with ethenol appreciate that Walbro has included the teflon and acetate pump diaphrams in their kits.

With 10% ethenol in the gasoline.......the rubber diaphrams last about a week.

Our state legistrators mandated ALL gasoline must be mixed with 10% enthenol without doing any research and boaters stated getting stranded in the Pacific ocean, classic car collectors with carburators started having many problems and landscapers and yard workers were wondering why their weedwackers and lawnmowers needed to have the carburators replaced freqently.(repair shops were loving it)

It seems ethenol causes rubber to dry out and crack.......

The state got worried and allowed boat yards and maraina's to start selling gasoline without the 10%.

Walbro came to the rescue and has started to include the non-rubber diaphrams in the rebuild kits.....my Quadra's are running normally again.

Thanks Walbro

Yet, DA seems to suggest that the Mylar solve-all replacement does not seem to pump sufficient fuel. What a load of....
I'm grabbing my head in despair.

Its really not the ethanol that is causing your problem. My guess is that they also reformulated the gas to include other chemicals that is the root problem. Every gasser I have still has the black rubber diaphrams and we have had ethanol in our gas for many years ..... even decades now. I believe that my state produces more of the stuff than any other right now. Now I'm not supporting the use of or supporting the use of ethanol ..... that is a political question I won't go into ...... but please don't blame ethanol when it isn't the problem. Reformulated gas and ethanol use go hand in hand ..... ethanol becomes the scape goat when people start having problems. I believe that gas in my part of the country has less of those nasty chemicals that really cause the problems. Therefore, I don't have carb problems when I use gas containing ethanol. Yes it is good that Walbro now supplies diaphrams that are resistent to these chemicals whatever they are. Any MSDS sheet for gasoline lists these chemicals if you are curious what they are.

Yes, both of my DA engines have the rubber diaphrams ..... one is almost 3 years old and the other is going on 5 or 6 .... still in perfect condition with plenty of 10% ethanol mix through them.

Interesting stuff, thanks guys

True, all of it.
Methanol takes about a year to harden the membranes. The combined actions of the several ingredients to oxeginate the gas are however very complicated, so it is easier, and maybe better to blame the ethanol. Pure oldfashioned gas did not cause problems at all. Some of the new blends cause problems in mere minutes! (not blaming any particular ingredient)

Well I am no chemist I am just relating what happened here when the ethanol 10% law went into effect......maybe they mixed pineapple juice in I don't know.

But those problems I related are real....and if wasn't the ethanol why did the state allow regular gasoline without the 10% ethanol mixture be allowed to be sold Marina's.

I know I was replacing the diaphrams very regular before Walbro introduced the diaphrams that were not rubber.

Here is a quote from a G23 manual

1) Never use any alcohol fuel or alcohol added fuel, or the rubber parts in the
carburetor. If not, the engine will be damaged.
2) Gasoline is very flammable. Avoid smoking, bringing any fires near fuel.
3) To prevent all possible problems on fueling system, make sure to use the fuel filter
which has more than 300 mesh or equivalent and gasoline proof rubber pipe or
equivalent.
Fig.2-A Fig.2-B

As I said, thanks Walbro.

I'm not questioning that you and others had problems as you clearly did. I do question the true nature of what caused those problems. Pe best described the complex nature of our current gasoline and the problems it can cause .... a "combined action of several ingredients".

In my state, ethanol was first introduced in a 10% blend in 1978, has been widely available since 1980 and there has been no mass of problems with its use. Last year, I believe that about 80% of all the gasoline sold in Iowa contained Ethanol. Sure there were problems early on with the solvency of ethanol causing gunk to be released from tanks ... plugging fuel filters, etc. Some fuel lines in those days would soften, etc. But those things were relatively minor and are long past. I have chain saws that are older than 1975 that are still going strong with their original rubber carb parts and they have been soaking in an ethanol mix for a very long time.

Some years ago, I had a friend that was a rep for Phillips Petroleum. He alerted me to the true nature of gasoline and that even back in the 1970s, gasoline was a dumping ground for many petrochemicals. Especially in winter when the cold temperatures allowed the blending of some of the lighter chemicals that would easily evaporate from what was then unsealed storage or cause vapor lock problems in warm months. It is interesting that with the occasional discussions of gasoline in these threads that we never hear from anybody that works in the petroleum industry. That could make for some interesting discussions. I would be curious to know what they put in the gas in Hawii besides ethanol. Would also be curious to know where gas in Hawii is refined. Are there refineries there?

Ethanol used in gas is not a pure chemical by itself as law requires it to be denatured. Here it is usually denatured by adding 10% of a pure gasoline product. So the 10% ethanol in our gas also contains 10% of something else to denature it. Some areas of the country use methanol and I'm sure other substances are used elsewhere.

I hope I didn't hijack this thread but I guess it does apply directly to carb diaphrams and the effects that fuel has on them.

I use the 2 black ones.

I did some not very scientific testing with all 3 types of pump diaphragms. My conclusion was that the blue acetate type pumped far less than the other two. I also concluded that the rubber one was slightly better than the teflon type. (contrary to the opening post)

**Can anyone verify the fact that the teflon pumps more/better/stronger than the rubber ???

the question is not:"does it pump more?" The blue mylar, being less flexible will clearly pump less fuel if it is to pump against a zero pressure test vessel.
The question is: "does it pump enough?" As long as the available membrane surface/stroke can deliver all the gas an engine needs at the pressure that the regulator needs there will be no problem.
If I look at the amount of gas being pumped without the regulating needle installed, there is no doubt whatsoever in my mind that the blue membrane will do very well in engines of at least 150cc and probably even more. These engines most of the time have the larger carbs installed, which again have a larger membrane surface, so pumping quantity is never jeopardized.

Maybe in Iowa they use corn and in other places they use something else...... to make ethanol.

I know our state leaders? decided to pass the law " to reduce our dependence on foreign imports" then someone told them we have no facility here to produce ethanol so guess what, we are importing ethanol! Probably from some where it's made from fish heads or something... the price went up also.....and gas milage went down...we pay more for gas BUT the state makes more from the gas tax.
Then they got a pay raise.

I'm glad it works for Iowa....

I think that ethanol is pretty much ethanol regardless of how it is produced. Anyway, ya just got to love it when politicians get involved in things they really know nothing about ..... and tell us its good for us!

Ethanol production here has become a big industry with corn planted pretty much fence row to fence row this year. Due to demand, the price of corn has pretty well gotten to or above the level where the ethanol producters can still produce at a profit. Politicians across the county continue to demand the use of more ethanol even before there is enough supply to fill the demand. Additional ethanol plants are being put on hold now because there is a question whether there will be adequate corn supplies to supply both the ethanol producers and the traditional corn processors and other users ..... such as FOOD. Can you see where I'm going here ...... soon the ethanol producers will be demanding subsidies because they can no longer produce enough product or produce at a profit. Yet politicians have dictated that ethanol be used pretty much country wide when they had no idea where the supply would come from. Heck, one day Iowa may become an ethanol importer!!!!

Ethanol might be good for Iowa and the country in the short term ..... not so sure about long term. I defend it when I hear people blaming it as the sole reason why diaphrams curl up, harden, etc. but don't completely support it otherwise. End of rant ......

Introducing ethanol into motor fuels was only good for the corn producing states. It had nothing to do with pollution or increasing fuel mileage. Matter of fact. it increases pollution because you have to burn more fuel for the same number of btu's, and reduces mileage. Ethanol was all abougt money, the same as MTBE. With MTBE it was a poisonous byproduct of gasoline production, later shipped to and stored in Canada, and sold back to the fuel manufacturers as an "oxygenator". When it was outlawed it became a political "hot potato" because of NAFTA regulations which brought some serious financial penalties into play from the termination of MTBE use.

Every time California has re-formulated the gasoline based fuels for motor vehicles there has been a rash of engine compartment fires amongst older vehicles. Each formulation has caused the latest, greatest fix from the last time to melt away. Get used to it folks. There's no rhyme or reason to what's being done with gas formulas other than locating additional profit centers. What happens to your vehicle or other engine powered appliance is purely secondary, and of little consequence to the manufacturers.

I don't remember saying; --> **Can anyone verify the fact that the teflon pumps more/better/stronger than the rubber ??? [&o]

I believe the surge diaphragm is for carbs with a fuel bulb. I don't know which of the others pump more, but both pump enough. As to which is better?--->???

Thanks Pat.
That does make the most sense so far.
When you say "both" pump enough, which two are you referring to.
Seems like there is neoprene, teflon, and acetate.

Take care
Bob

I need to replace the black diaphram on my DA100 but am not sure which model carb DA uses as they grind the numbers off (why is that). Can anyone tell me which carb is on the DA100 or which kit I need to buy. Thanks.

Carb on the DA 100 is Walbro WJ71.
Diaphram kit is D10 WJ.
Not sure what the rebuild kit number is?

http://wem.walbro.com/walbro/product...um=WJ%2D71%2D1