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FMQ Blowing Fuses

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  • FMQ Blowing Fuses

    Revising a really old thread. I own a FMQ 2-36 and this week I noticed the fuse went out. I replaced it and after it start it went out again. The unit does sound like it isn't starting - almost sounds the motor is trying to turn but it is seized. Any guidance on where to start?

  • #2

    First, in this situation, start a new thread. It will go to a lot more people.

    Now, to your problem. You need to replace one of the three modules. Most likely the compressor module, but it could also be the lower 'control module' or even the 'electronics module.' I would replace them in that order if I had all 3 handy (which I do). If not, I would start with what I have. Or call a Fuelmaker technician. They may charge a lot for their time but they will get it working in one visit.
    02 GX
    01 GX
    03 Crown Vic
    06 GX
    Home Fueler

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    • #3
      Best you can do is to look for an amperage draw on the incoming electric. (full load 7 amps)
      Next best is to pull the compression module and give the rotor a spin. 4 bolts but back them out evenly 2-3 turns at a time. Make sure the oring is in place when resetting the module in place. (these are aluminum parts so don't go crazy with torqueing them. (use a little locktite and just tighten firmly)

      If you aren't comfortable with the mechanical side... get a competent service person.

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      • #4
        Most likely either the motor start or the run capacitor has gone bad. Fairly easy to borrow one of similar microfarad capacity from another motor and swap it in to see if it is the problem.
        I had a problem where the wiring inside the control module was blackened from a possible short due to damaged insulation in conjunction with the bad capacitor.
        I ended up throwing a bunch of parts at it and ultimately sending it back to Energy tree to get it diagnosed and repaired. It was overall a very disappointing experience for a variety of avoidable reasons.

        This was the final straw in me losing interest in my fuelmaker. They would be a great unit if there was manuals and parts available for owners wanting to do their own repairs.

        If you want to do your own service and it is worth your while to run on CNG it is worth following TRDFJSC's lead and getting a Coltri import. Nothing will match the simplicity and safety of operating a fuelmaker if you don't mind having to hire the service tech.

        Karl

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        • #5
          More than likely, the motor winding is near shorted (resistance too low), in which case you will need to replace the controls module.

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          • #6

            don't start throwing parts at it till you know what the issue is.

            If it tries to start and blows a fuse immediately, pull the compression module and give the rotor a spin. If it spins, ohm out the control module wiring. Ohms should be 1-4=6.5, 2-4=2.7, 1-2=3.8

            If that fails to provide the answer check the capacitors and contactor. Look for burns on the fuse ends and or fuse holder burn marks. coat the fuse ends with dielectric grease.

            As for the other brands of compressors, the BRC Fuel Maker are the only compressors certified as appliances by the AGA and exempted from many of the 2013 NFPA 52 regulations. Depends on your inspector if the other brands can be installed and operated. So much of what several here on cngchat claim to be doing is way less than legal. Make sure a machine can be installed before spending money on it.

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            • #7
              Check the fuse holders, I've had to replace them on both my FMQ's. You may not be getting a good connection

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              • #8
                If you mounted the storage tanks on a trailer would that get you around the restrictions on having cng fuel storage tanks?
                It would be fun to hear the airplane was getting converted to CNG but I am assuming it would throw off your center of gravity and severely limit your range.

                Thanks for sharing,
                Karl

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                • #9
                  Hey gang,
                  I had to remove a bunch of posts which where were unrelated to the topic. If you have comments and suggestions on FMQ blown fuses then post it here. Other topics require starting new threads or adding to existing threads on a similar topic. Thanks.

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                  • #10
                    Not sure how much I should say here because the following information may result in more questions. As stated above the motor condition should be looked at first to determine if it freely turns and the general condition of the stator windings (for any discoloration, burnt smell, varnish peeling, other). If the rotor looks like it is mechanically touching the stator I'd correct this with whatever mechanical parts are worn - not too probable. I would then check the capacitor - if you do not have the equipment to do this I'd get with an electronics technician. If you are using a replacement capacitor (same ratings/specifications but different manufacturer/part number) I'd make sure you don't get a Chinese made one - I've tried this once before and the capacitor latest about a month before it blew apart - literally. I've seen the fuse holders get brittle due to heat. Replacing them may improve the connections but probably not correct the root cause of the high heat that led to them becoming brittle. I've had to replace a transistor and resistor before that controls motor current. For me one of the resistors was discolored indicating an overheat and a transistor was damaged as a result. These circuit cards are old technology and it is rather easy to replace components, however, one would need to have reasonable skills desoldering and soldering components. My opinion is that one should not need to ever replace the module, just repair a failed component on the module. Note: unless the root cause for the failure is rectified the same condition may return. There are folks on this forum wanting to buy the control module that could be easily fixed for a few dollars in electronics. The only components that could not be easily replaced are the memory components since they have a unique program in them - but the probability of them being failed is low.

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                    • #11
                      Thanks for all of the responses everyone. I have next week off and will take a stab at the unit. Will report back, it's been pretty annoying having to pump at PG&E twice a week for the past month. It is interesting though, seems like pumping at home vs pumping PG&E is basically a equivalent in terms of savings (Electricity and gas). I am guessing now that my unit isn't running as efficiently anymore it is drawing alot of current since it takes about 30% longer to pump now.

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                      • #12
                        Keep in mind the 2 15a fuses are slow blow, if the new one is not a slow blow it will go right away. To me the easiest process is when ready to start put an amp clamp on one of the line voltage wires, and start the compressor, if the amp hits around 30a compressor seized, you can also pull the comp and try and rotate rotor, you should check motor windings either way. amfuel is right the ohm values should be that or close. I dought its the electronics, if the caps were bad you would get readings of 14-17a start and 7-9a run. New compressor would be around 22a start and 5.5a run

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                        • #13
                          Welp, I have some bad news on my part. My car was rear ended and looks like the car will be totaled based on repair costs. I don't think I'll be buying it back - so most likely i'll be putting this fueling unit up for sale. Any idea what this should be listed for?

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                          • #14
                            I have a similar problem with my FM4-10. It is blowing fuses as well. I measured the pins listed above, and the resistance values are close to what is listed above. I removed the compressor module. The compression module spins freely, and I don't see any contact. However, the windings on the control module are covered with a brown dust and it smells burnt. I have a spare controls module and compressor module. What additional tests do I need to do before replacing controls module or compressor module or both? Is there anyone that can repair my compressor and control modules?

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                            • #15
                              Before starting the machine press and hold the stop pad. What lights come on? Whichever lights are on steady or flashing is the error code while holding the stop button. (pad)

                              Does it start and run 7 seconds then change sound as it goes into the run mode?

                              How long will it run before a fuse blows? Is it the 15 amp fuse on the board or the wall fuse? (or circuit breaker)

                              On the ohms at the 9 pin connector is the 1-4 pins above 6 ohms?

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