Belite fuel level.

[vwglenn]

OK, putting on my Debbie Downer beret, but couldn't one just put a small door or window in a 2.25 hole in their panel and shine a flash light under the panel to accomplish the same thing?

I started with that idea. Just could't find a place in my panel that it would work. Even thought about installing some sort of periscope.

[Bryan Cotton]

My wife backed into a pole last week. I bought an ebay camera/monitor for the truck to try it out. Should make hooking up to the trailer a snap.

[Sonex1517]

I wanted to update this thread with an experience from this past weekend.

I flew a couple of hours off my phase one this weekend. While doing so, in an ongoing effort to get my fuel readings accurate, I trimmed my fuel vent further so it was up inside the cowling. I should note here I have the "smile" in my cowling taped over for air flow to the engine. It runs cooler this way.

My first flight I thought I felt some roughness, but nothing I could be certain of, and nothing that alarming. Temperatures were good, oil pressure and temperature good. No indications in change of RPM or manifold pressure (I have the turbo AeroVee).

Nonetheless, I cut my first flight short and returned to my home airport, pulled the airplane in the hangar, removed the cowling and went over everything I could. No problems found.

So, I went out on a second flight. Again, it felt a tiny bit rough. Nothing severe, nor any indications of a problem. I thought I was imagining it.

After just over an hour of uneventful fun, I felt a definite change in the engine, and it was strong and long enough to make me turn towards an airport nearby. As I did so, the engine stuttered. It didn't quit, it didn't cough, it just stuttered. I pushed the stick forward and the engine ran smooth.

At this point it had occurred to me I had never had this issue before, and the only change was trimming my fuel vent. When I landed, I moved the fuel vent back outside the cowling again. I did not fly again that day so I have nothing more to report yet.

I emailed tech support at the factory. They confirmed that trimming the vent could have caused a change in fuel flow - the head pressure on the system is low enough a slight negative pressure would be a possible cause of this.

At the risk of being flamed here, I wanted to pass this along in hopes it assists others.


Robbie Culver
Sonex 1517
Chicagoland
N1517S

[fastj22]

Robbie,
My Belite module is back at the shop getting fixed because I got stupid and plugged the power into the probe port.
But this idea that ram air is causing high fuel readings and a trimmed vent causes it to go low has me skeptical.

When I get my module back, I'm going to do a ground test. First I will measure fuel with ambient pressure. Then I'll pressurize the tank via the fuel vent by a few PSI. Recheck. Then I'm going to plug the vent and disconnect the fuel line to the carb. This should create a vacuum. If the readings are all over the place, I'll agree its a vent issue. If the are really close, its something else. Before I smoked my module, when in flight, I'd see fuel level go to zero on my MGL. ZERO! No pressure on the sensor. But I had fuel and the engine was running swimmingly. It would come back up to normal while taxiing.

I bought the Belite LED display and that's when I trashed the module so I can't say its the MGL or the Belite.

[Sonex1517]

Thanks John. While BeLite has been good to respond, they also did not seem to have anything to say other than telling me it was a pressure issue. I spoke to Jim on the phone once during my efforts to resolve it.

I am keeping the BeLite probe and computer in case this is something I can resolve, but I don't trust it right now at all. I may send it back to have them look at it.

Just to go back to the beginning of my description, it showed full on the ground and after takeoff then dropped rapidly to empty in flight when I could see I had a full tank.

They suggested I change the vent so I did by adjusting it to point more into the slipstream. That made it show full all the time no matter how long I flew.


Robbie Culver
Sonex 1517
Chicagoland
N1517S

[Mike53]

Thanks Robbie ,for the update.
It would appear the Belite probe is just too sensitive to even the slightest positive pressure and you have proven that going the other way i.e. shortening the vent further has the opposite effect.
I'm sure the air under the cowling at the firewall has a lot of turbulence from air leaks etc.
My question is,if Belite has sold a lot of these how are others making it work in other types of planes?All fuel tanks require venting,or are we just not hearing about them?
Suffice it to say I have a Belite fuel probe for sale.
Cheers,
Mike

[fastj22]

Mike you beat me to it.
I really want to make this work but am running out of hope. I'll wait for my module to be repaired and try one last time. But it will be on the market if I can't.

[Sonex1517]

Thanks Robbie ,for the update.
It would appear the Belite probe is just too sensitive to even the slightest positive pressure and you have proven that going the other way i.e. shortening the vent further has the opposite effect.
I'm sure the air under the cowling at the firewall has a lot of turbulence form air leaks etc.
My question is,if Belite has sold a lot of these how are others making it work in other types of planes?All fuel tanks require venting,or are we just not hearing about them?
Suffice it to say I have a Belite fuel probe for sale.
Cheers,
Mike

Anyone frequent the other forums? I'm off to surf and see....


Robbie Culver
Sonex 1517
Chicagoland
N1517S

[Corby202]

Although mine is working fine and is accurate I wouldn't go so far and recommend it for use in a Sonex. I have been very lucky to get static pressure in my fuel tank plus having fuel pumps I do not need any ram air to pressurize the tank. I think on most planes (ultralights) with a vented fuel cap again there would be no problems, I think this what the Belite system was primarily designed for. Also not helping on a Sonex is the large surface area so a change in angle of the plane causes a change in fuel quantity reading.