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Carb floats

Jcurry

Well Known Member
Are you guy's still having issues with the carb floats? Doesn't seem to be too much chatter on the subject lately. Is this because everyone is getting use to having to change them you think? Or have the floats improved? My engine ran extremely rough the other day so I placed the MS floats on order.
Like to hear your .02
 
Nothing is for certain.

Friend has a RV-12 Legacy finished in 2015 with 340 hours on the Hobbs. Past 3 years have been nothing but Costco Premium Unleaded Mogas bought in Southern CA, from 120 hrs to current being Mogas Unleaded, with some (not a lot, mostly winter months) ethanol in the fuel.

Knock on wood, his floats are fine.
 
Bing carb presentation

At Oshkosh this year I attended a Bing carb presentation that Brian Carpender, of Rainbow Aviation, who talked about the float issues. He said the reality is the reporting systems now in place made the sinking float issue seem like a big deal all the sudden. When in fact he said sinking floats have been happening for many years and that any “new” floats become the latest test float out there. It’s the reporting systems in place for all things Rotax and Bing that bring the issues to light sooner today.

I am running my original floats since 2013, knock on wood, and they have weighted out good each annual. I have a spare Marvel set ready just in case and those using these blue floats so far the few reports I’ve seen on VAF have been favorable.
 
Debris at condition inspection

My current plane is a SeaRey LSX with a Rotax 914. I deferred the (third for me) float change until my condition inspection a couple of weeks back as I wasn’t having any issues. During the inspection we found float debris in one of the bowls of sufficient size to potentially clog a jet. The floats weighed OK but the debris was troubling. Happy I had already ordered the replacement set. Kept the older pair to keep in the plane in case of AoG emergency, but I think I’ll be a little more diligent in complying quickly in the future. YMMV.
 
My 2015 -12 has 820 hours on it. I changed to Marvel Schebler MS80-430 floats on 1/9/2021, that was 210 hours ago. Since changing to those floats ALL of my random mixture issues have disappeared and my fuel economy is fantastic.

The type of issues I would experience before were an occasional smell of gas on landing or during a pull up. I had replaced the black floats several times in the year previous including many weight checks.
 
I switched over to the Marvel Schebler MS80-430 floats over a year ago (160 hrs) and have had no additional issues.

Gary
 
desperately seeking solution

Trying to resolve my rough running* 912 ULS and whether it's ignition or carbs.
As for carbs, what is normally the depth of fuel in the bowls?
Appears mine are about 3/8" below the top of bowl.
Note that floats (Rotax late model R designation) float at pin level and they weigh 3 grams each.
Addnl note, plane & I have been down for a month (condition inspection time of year) so today I'm going to drain fuel and try fresh gas (grasping those straws).

* longer story of symptoms & troubleshooting available upon request, but it aligns with similar stories as told here on VAF ;)
 

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Trying to resolve my rough running* 912 ULS and whether it's ignition or carbs.
As for carbs, what is normally the depth of fuel in the bowls?
Appears mine are about 3/8" below the top of bowl.
Note that floats (Rotax late model R designation) float at pin level and they weigh 3 grams each.
Addnl note, plane & I have been down for a month (condition inspection time of year) so today I'm going to drain fuel and try fresh gas (grasping those straws).

* longer story of symptoms & troubleshooting available upon request, but it aligns with similar stories as told here on VAF ;)

Have you confirmed that your carbs are synchronized? I did mine step by step per Van's and discovered the idle mixture screw turned out to far on both carbs.
 
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Trying to resolve my rough running* 912 ULS and whether it's ignition or carbs.
As for carbs, what is normally the depth of fuel in the bowls?
Appears mine are about 3/8" below the top of bowl.
Note that floats (Rotax late model R designation) float at pin level and they weigh 3 grams each.
Addnl note, plane & I have been down for a month (condition inspection time of year) so today I'm going to drain fuel and try fresh gas (grasping those straws).

* longer story of symptoms & troubleshooting available upon request, but it aligns with similar stories as told here on VAF ;)

I almost hate to tell this story, but I struggles for almost 2 years with that same issue. I went through several carb rebuilds. I did it a couple of times, as well as a reliable shop trying it 3 times. It always ran great for a short time after each carb job. After an hour or so, I was back to the rough running, flooded condition.
Long story short, I finally flew my 12 down to Lockwood Aviation in Sebring Florida. The service manager asked the owner, Phil Lockwood to test fly it. He took considerable time in a preflight. The interesting point was that when Phil sumped the gascolator, he took several samples with the standard sump tool and poured them into a clear funnel shaped container to get a better view for particles. He found microscopic particles and asked that the fuel system be cleaned out before he would fly it, The shop also found some of these microscopic particles while disassembling the gascolator. They then test ran it for quite awhile with fresh fuel and a cleaned out fuel system and than made arrangements for Phil to try again to test fly it. Phil went through the same routine only he probably took 4 or five fuel samples this time. He walked back into the shop and told them to pull the tank, which they reluctantly did. While continually flushing the tank into a white bucket, it was obvious that these microscopic particles was actually deteriorated pro seal. I had to order a new tank from Vans, which Lockwood installed and the problem is gone. My only explanation is that when installing the mandatory fuel tank mods, I must have had bad pro seal. It was old, was kept refrigerated, and I tested it before using it. Lesson learned, the hard way. I have no other explanation other that that it runs very nice now. So don't overlook the tank when troubleshooting....Tom
 
Happy to report the Rotax is back to its smooth self :D
Evidently the fuel refresh was just what the doctor ordered.
Actually, it's what Scott McDaniels had mentioned in another thread (912uls Spark Plug Diagram) where he said, "I have seen poor fuel cause strange issues, particularly in cold operating conditions."
Emptied the tank & put in a blend of 93 octane MOGAS (3.5 gal) and 100LL (2 gal) for a trial run.
Once the oil warmed up enough to perform "mag checks", all was back to normal and running smooth.
Mr. McDaniels input is so valuable (sure am glad he watches over us!).

Note, I had been troubleshooting under the impression that the gas wasn't bad since it was less than month old 93 octane non ethanol (wallyworld stuff :mad:)
 
Is anyone else using a fuel preservative? I have been using one oz. of Seafoam per gallon for over 4 years / 300 hours and have never had a fuel related issue. I use 93 octane with 10% alcohol with the occasional refueling of 100LL on cross country. Seafoam states that it preservers fuel for up to 2 years, of course I'd never consider letting treated fuel sit that long but there are times such as now when I've been waiting nearly 2 months for my D-180 to get back from Dynon.
 
Is anyone else using a fuel preservative? I have been using one oz. of Seafoam per gallon for over 4 years / 300 hours and have never had a fuel related issue. I use 93 octane with 10% alcohol with the occasional refueling of 100LL on cross country. Seafoam states that it preservers fuel for up to 2 years, of course I'd never consider letting treated fuel sit that long but there are times such as now when I've been waiting nearly 2 months for my D-180 to get back from Dynon.

I fly regularly enough and rarely leave fuel unused for more than a couple/three weeks so have never used preservatives in the -12. I've heard talks from Phil Lockwood who encouraged the use of fuel stabilizers when the fuel will not be burned for several weeks or so. If I recall correctly he had done so with Stabil in Rotax engines and didn't have any concerns.
 
I replaced those pesky carbs 1,500 hours ago. Had waited over a year for warranty replacement floats. Edge Performance fuel injection conversion was plug and play. Benefits: 10% increase in HP, perfect fuel/air mixture at all times/altitudes, easy starting direct injection, much lower idle allows shorter landing distance, no more carb balancing or float issues, more efficient equals better gas mileage, super reliable automotive parts (less expensive and readily available) however I’ve not replaced a single part since I converted.
Disadvantages: NONE (besides the initial cost which I believe has more than paid for itself.) The conversion comes with a 2-electric fuel pump manifold. The system is lighter weight overall than the carbs on the 912ULS.
 
Kitplanes

Nice article in this month's Kitplanes Magazine about this EP-conversion. I am still very happy with my two carberettors, but after reading the article I understand your enthusiasm.
 
I replaced those pesky carbs 1,500 hours ago. Had waited over a year for warranty replacement floats. Edge Performance fuel injection conversion was plug and play. Benefits: 10% increase in HP, perfect fuel/air mixture at all times/altitudes, easy starting direct injection, much lower idle allows shorter landing distance, no more carb balancing or float issues, more efficient equals better gas mileage, super reliable automotive parts (less expensive and readily available) however I’ve not replaced a single part since I converted.
Disadvantages: NONE (besides the initial cost which I believe has more than paid for itself.) The conversion comes with a 2-electric fuel pump manifold. The system is lighter weight overall than the carbs on the 912ULS.

Interesting. I have been wondering if anyone did this on a stock RV12?

Any more info you would care to share? Did you do the conversion yourself?

Cost for the conversion kit?

ELSA? did it create any regulatory issues? (yes the old major versus minor modification debate...)
 
Stabil 360

I add 1 oz. Of Stabil 360 to very 5 gallons of premium fuel I purchase at Costco. No issues so far. I live in Ohio, so occasionally, in the winter I go 4-5 weeks without flying.
I am using the second generation Marvel Schebler floats, after 3 sets of the sinking Bing floats, and 1 set of the original Marvel Schebler floats.
 
Carb float’s

I replaced the floats with the new Bing R floats when I rebuilt both carbs. almost a year and half ago and 140hrs. ago. I used them because they came in the Bing level 5 overhaul kit from Edge Performance, which was by far the best price at the time. Just weighed them at annual inspection again and all were 3.2 grams and looked good. Maybe Rotax - Bing finally got it right? Plane has 860 hrs. on it. Had a few heavy floats before.
 
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