RAF Fuel Gauge and sending unit

[BadAir Express]

I was wondering if someone out there has the instructions to set the low and high marks on the RAF fuel gauge. Also I thought I read somewhere about how to test the sending unit... Ohms value? Is this system at all reliable or is there something out there that is better?

Enjoy the good air and Whip the BadAir into submission!

Curt

 

[asmuzsr]

I'll try and remember to look in the instruction I got for that. I'll be back at the hangar Monday. Best thing is a sight gauge and knowing your fuel burn and how much you put in the tank. Never trust the gauge.

 

[BadAir Express]

I know your right when you say, "Never trust a guage." I was hoping these would be fairly accurate. What's everyones thoughts about a sight guage. I've seen one that ran up the mast with a little valve at the top and some markings on the side. Does anyone have photos of one in the cockpit? If so, what would be the best way to install one after there has been fuel in the tank? And yes, Tony, If you can find your instructions, I would really appreciate a copy.

Curt

 

[asmuzsr]

Well if you have fuel in the tank you'll need to drain that out. I have one of those tubes with the ball valve on the end. You put that in the tank and shake it till the furl start to siphon out. Now take the fuel line on the passenger side and put T fitting in it just before the pump. Run clear tubing up the back of the cabin and drill a hole so you can put it on the vent line. Course you'll need another T there so the tank can still vent. Just below the hole you made for the line to go into the cabin put a shutoff valve. You need this so you don't suck air into the system while flying. Now put "Adel" clamps on the line coming up the back of the cabin and rivet it to the cabin. Now put 5 gallons of gas at a time into the tank and mark it with what ever. I just used a Sharpie on the cabin. Keep putting 5 gallons in and marking the 5 gallons till the tank is full. Open the shut off valve while doing this so air isn't trapped in there and give you a false reading. Now you should be good to go. During your preflight as you walk around open the shutoff valve so the gas level can stabilze and there's your level. Then close the valve again. Now one thing to remember. As the gas level goes down and can't cross over the hump in the middle of the tank, you'll only be checking the level in that side of the tank.
This is what I did on my old style tank and it worked well for me.
The new style tank won't work this way as the top back of the seat is not part of the tank. It's all over you.
If you's like to talk call me. Some times things don't come over the print well.

 

[BadAir Express]

Hey Tony... I was wondering if you found those instructions. I'd really like to give the gauge a try and as you suggested, I'm installing a sight tube today...

Thanks Curt

 

[asmuzsr]

Sorry I forgot. Will write a note to look them up tomorrow.
Is it the old gauge or that new "funky" looking thing with the dots?

 

[WHUBBS]

Fuel gage problem, i have the RAF gage that has the dots that light up, my tank is full of foam, when the probe is inserted and incontact with foam, how would it know and read the fuel level?? i calibrated the gage per the specifications, when new, and all seamed to work for a while and now when the master switch is turned on, the gage goes to full and always stayes there, no matter how much fuel is in the tank. i installed a sight gage. any ideas of what has happened.

Wayne Hubbs

 

[BadAir Express]

Mine is the 2002 era with the dots around the gauge that light up. The bottom two holes have a place to push switches with a small pointed object. Thats what I'm looking for is how to use those push switches. I think...:-

Curt

 

[WHUBBS]

Curt, if i remember correctly, my instructions said to put what ever you want of fuel in your tank ( SAY 5 GAL. ) as the low limit, push the button, the bottom left hole and that will set the low limit, then fill your tank up and push the button on the right bottom of the gage. this should set the high limit, i did this when my machine was new and it worked for about a month, and then it started going to full all the time after the master was turned on. i used a tooth pick to push the buttons. i have drained all the fuel out of my tank and started all over a couple of times, but even then, it still goes to full, i give up and just put a sight gage on the outside with a shut off valve at the top of the tube and all works well. i have thought about just taking the RAF gage out of the dash, and adding a German Becker Transponder, to match my Becker com radio, using the same hole, then my problem is solved but at a much larger cost.

Wayne

 

[asmuzsr]

Hey Tony... I was wondering if you found those instructions. I'd really like to give the gauge a try and as you suggested, I'm installing a sight tube today...

Thanks Curt

I checked my instructions and their the same as Waynes, put in 5 gallons and push the button then fill the tank and hit it again.

 

[Harry_S.]

Might I offer a point for discussion?

I have the analog indicator but the problems seem to be similar to the idiot lighted indicator.

After 2 or 3 yrs. of frustration in trying to get a happy medium with the indicator...I did this. Maybe it will help you. By the way, the indicator is set at the head of the fuel probe on my machine.

I have the upright seat tank which fills from the top of the tank and when fully loaded with 23 gals. the fuel is all the way to the filler tube.

I put 5 gal. in the tank and put a line on the front of the tank (the machine is in a level attitude), and adjusted the indicator to EMPTY. I then added another 5 gal., marked the tank and set the indicator to FULL.

The ten gal. level will just about be at the horizontal seat level. Any fuel qty. above 10 gal. will register as full on the indicator. The upright part of the tank will hold up to an additional 13 gal. This means you will burn more than 13 gal. of fuel before the indicator starts down from the FULL indication. I've only filled my tank I think twice in 11 yrs. and each time I flew more than 2 hrs. before the indicator started down from the FULL mark.

My machine is still in the keel level position when I pre-flight...reason being to check the oil and fuel levels. If the fuel is out of sight on the seat, I know I have more than 10 gal. and I'm not gonna fly more than an hour; most of the time anyway.

Hope this helps.


Cheers

 

[BadAir Express]

That's a great idea Harry. I talked to Tony today and he talked me through the proceedure to set the gauge. He's going to fax me a copy of his instructions so I'll have one with my build book. (I've lost mine somewhere) If that works, then I think I'll do the same as you did. Thanks for your help. I'll let everyone know how it works out. P.S. I put some photos on the builders thread. (I think. Might be Chapter 2 Utah site. Can't remember.)

Thanks again.


Curt

 

[willisbr]

I think my probe is bad. I have the RAF gauge with the arc of lights. Has anyone kept this gauge and just replaced the fuel probe? If so, which one? And can I continue to set it using the buttons on the gauge? If I can't get a yes answer on any of this, is there a preferred replacement of all of that? And I have all the info I could want about a site gauge, so no need for references for that at this time. Thanks.

brian

 

[asmuzsr]

Dofin recomends Westtach gauge and prob. I put one in and it's good. Plus it's a regular looking gauge not that stupid light thing. Give him a call and he can tell you which one. I haven't been out to the hangar for a couple of weeks due to a cold and models filling up the garage. Biggest offender is a 53" electric, Bell 47.