Janitrol Fuel Solenoid

Hi Scott -

I'd like to get your recommendation on this maintenance issue. The heater in my PA34 (90D38-1) will sometimes go in to overheat shutdown, usually under ground operations. A bit of troubleshooting shows the fuel solenoid valve sometimes remains open (flowing fuel to the nozzle), even though the cycling switch is commanding it to close. When this happens, the duct temperature rises rapidly from 60C to well over 100C, and shortly thereafter the overheat switch trips.

My questions:

  • is there some way to "free up" the solenoid valve so that it works properly, instead of replacing it?

  • It's hard to tell from the service manual how big a job the replacement is. Is the solenoid valve field replaceable - something I can ask my IA to do? Or would we be better off shipping the entire heater unit out to an expert for repair?

  • Piper lists the part as 757-792, which is not available through Aviall. Are there other sources for this, or other new equivalents? Believe the part was originally a Lake 44007, but they look to be long gone.

thank you,

Bob Tingley


  • Hi Bob,
    I have about 30 years of using Janitrol heaters and they've been very good to me. I have had a couple of issues and I see you're having one, too. First, your safety is paramount and an overheat, while protected by a thermal cutout, is very dangerous. I would recommend sending it out for overhaul/repair immediately before something bad should happen. Next, when it's out check all of the duct work for crimping. I had a passenger put their full weight on the center floor duct once upon a time and crimp it causing an overheat. Check the whole system. good luck.

    Scott Sherer
    Wright Brothers Master Pilot, FAA Commercial Pilot
    Aviation Director, Piper Owner Society Forum Moderator and Pipers Author.

    Need help? Let me know!

  • There are new 757-792 solenoids available if needed.

  • Scott - thanks, good advice as always!

    AW - thanks. just sent you an email.

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