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Thread: Rotax 912ULS Fuel Pressure Sender

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    Premium Member (Donated) s19flyer's Avatar
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    Post Rotax 912ULS Fuel Pressure Sender

    To hook up a fitting to the fuel distribution block on the Rotax 912ULS you will need a metric to AN adapter.

    Russel Performance makes some that you can get from either Summit Racing or Jeggs if you want.

    Part #'s are:

    670500 - AN4 to 10mm x 1.0
    670480 - AN6 to 10mm x 1.0

    Since I didn't install the fuel filter in the line downstream of the gascolator I used the AN4 x 1/4" hose barb that came with my kit and ordered the 670500 from Summit Racing.

    Dynon recommends not mounting the sender to the engine so I'll mount it on the firewall and run 1/4" fuel line over to it.

    Thanks goes out to Craig for the part number heads up as it saved me some research
    Glenn
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    Glenn, I want move my fuel pressure sender off the block to the firewall. Would you have a picture. Is the block metric/10mm is that the reason for the metric adapter and did you use an adel clamp on the firewall? Doug in IL

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    Premium Member (Donated) s19flyer's Avatar
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    Doug, yes I moved mine to the firewall and used 670500 - AN4 to 10mm x 1.0 to adapt it to the fuel distribution block. I used the 1/8" pipe to 1/4" hose barb on the fuel pressure sender but don't remember what size adel clamp it took. You'll have to measure the sender and then get the right size. Also you may want to mount it on the engine mount tubing off to the side and down low. Seems some have been getting varnish in them from the mogas cooking in the sender. This makes the fuel pressure indication go haywire. No problem if you mount it down low away from the heat that inveades the upper part of the cowling.

    Mines still on the firewall where I installed it for now.

    Craig may chime in and provide a pic of where he put his.

    You can see wheere I put the sender in the pic below




    But it's better to mount it low away from heat.
    Glenn
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    Thanks Glenn,

    Is the OEM fuel pressure senor 10mm?

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    Premium Member (Donated) s19flyer's Avatar
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    Doug,

    Not sure what you mean by OEM since I didn't get a fuel pressure sensor from Rans. I got mine with the Dynons and I think it's a VDO unit but I'm not sure.

    The 10mm x AN4 is for mounting to the Rotax fuel distribution block. You then use an AN4 to 1/4" hose barb, attach 1/4" fuel line (slip some firesleeve over it) and then attach it to the 1/8" x 1/4" hose barb fitting that is screwed into the fuel pressure sensor.
    Glenn
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    Basic Member craig's Avatar
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    FYI:

    I had to relocate mine from the top of the engine to the left side on an engine mount tube. After checking the rotax blogs, I found 10's of entries relating to failed or false reading fuel pressure sensors. Rotax attributed it to the use of mogas. After engine shutdown, the additives cook in the sensor, gum it up with varnish and it reads false from there on out. The solution is to find a cool place away from the engine. Mine exhibted the exact traits after about 50 hours. I finally got around to ordering a new one (VDO) and moving it. Pictures are at the link below.

    https://picasaweb.google.com/1100241...9/FuelPressure#

    Craig Schneider
    S-19 N519CS
    KMRT Union County Airport, Marysville Ohio

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    Hi Glen, did you leave the fuel pressure sensor there? What if I mounted to the rear of the big tube between the carbs. It has a bolt hole on the rear......or attach it to the top bolt of the regulator/rectifier some way. Its at a higher positon in both cases and the fuel can drain back down hill rather than going lower and getting stuck lower only to degrade??? Doug in Il

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    Premium Member (Donated) s19flyer's Avatar
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    Hey Doug,

    Yes, I've left my sender where it is at. So far so good.

    You don't want to mount the sender on the balance tube. That's technically still on the engine and subject to vibration.

    The top bolt of the rectifier will work but it's best to put it down low, away from heat build up.

    I don't think the fuel drains back out of the hose to the sender. But it might !

    Later
    Glenn
    Avid Flyer, S6ES, S19, S20 In Progress
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    Remember, I am not immune to mistakes!
    What works for me may not work for you.

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    Nervona-mounted a new VDO on the right upper engine mount by way of a welded empty fixture....thank goodness it was there, kinda looks like made to order. Covered it in fire sleeve and test run with no spiking indications. We'll see after a few hours how she performs.....last two; one VDO, and one Mitchell had 11ish on the Ohm meter, this new one is at 7.5...So both oil and fuel are off-engine and I hope to gain a little peace of mind if they'll perform as intended now. Thanks for the advice.

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