garytex Posted December 17, 2012 Report Posted December 17, 2012 Of late I notice that my fuel flow bounces around, fluctuating up to a couple GPH in a few seconds. It is progressively getting worse over the last couple of months, is steady at the beginning of a flight, seems to get worse after about 15-30 minutes of flight. Turning on/off the boost pump, radios, makes no difference. It also is affecting the fuel totalizer, which used to be spot on, which recently told me 31 gal burned, and I pumped 24. It's going to my mechanic next week. Anybody played this game before? We will round up the usual suspects, but there are a bunch of them. It would be nice to have some other folks experience with this. THANKS, Gary Quote
M016576 Posted December 17, 2012 Report Posted December 17, 2012 I've never had this problem, but it sounds like your fuel flow transducer (impeller?) is damaged or coming apart. That would explain the fluctuations in your fuel flow. The totalizer just tallies up fuel flow over time and makes the appropriate calculations. Quote
N601RX Posted December 17, 2012 Report Posted December 17, 2012 As the impeller inside the fuel flow transducer spins, it generates pulses. These pulses are counted by the controller and fuel flow is calculated. It could be the transducer going bad, or it could be picking up extra pulses from noise. It is also possible the timebase used to count the pulses is messed up. I would call the manufacturer and they can probably point to in the right direction. You didn't mention the brand, but the ones I had before all cautioned about short transducer life if mounted directly on the engine. Quote
garytex Posted December 20, 2012 Author Report Posted December 20, 2012 Thanks, Guys. I'll report back after we get to the bottom of it. Quote
Piloto Posted December 20, 2012 Report Posted December 20, 2012 I had exactly the same problem three years ago. Contacted the transducer manufacturer and he suggested soaking the transducer with carburetor cleaner. I sprayed the transducer inlets and then blowed air by mouth and was able to hear the turbine spinning. Put it back and since then it has been right on. The problem is common and is due to residues in the fuel that either impair the turbine from spinning smoothly or block the internal photocell. José Quote
garytex Posted June 26, 2013 Author Report Posted June 26, 2013 Turns out the fix was cleaning the oil out of the 2 pin connecter at the end of a little short pigtail that comes off the transducer. There wasn't much oil in the plug, but evidently enough to allow some shorting, or possibly some insulating of the connection. Quote
garytex Posted June 26, 2013 Author Report Posted June 26, 2013 The transducer was fire sleeved, the wires coming out were not. I subsequently wrapped the connector (after the second time it got oil in it and began to fluctuate) with some heat melding Scotch brand electrical wrap. It doesn't take much oil, my transducer is located under the left side cylinders near the bases which must be an oily place. I get a very small amount of oil out of the pushrod tube seals, and thats probably where the oil comes from and then gets blown down by the cooling air. Quote
ZuluZulu Posted January 10, 2022 Report Posted January 10, 2022 Resurrecting this thread because I'm starting to have this problem with my EDM-830. Note the FF and H:M indications in the video: there's a lot of noise in there. Has anyone else had this problem that required fixes other than those above? IMG_2835.MOV Quote
ZuluZulu Posted January 10, 2022 Report Posted January 10, 2022 Getting ahead of potential questions: OIL-T is not installed yet. I have Monroy tanks (94 gal capacity, configured as 93 gal in the JPI). This was in WOT cruise, 6500 FT. 1 Quote
Marauder Posted January 10, 2022 Report Posted January 10, 2022 Getting ahead of potential questions: OIL-T is not installed yet. I have Monroy tanks (94 gal capacity, configured as 93 gal in the JPI). This was in WOT cruise, 6500 FT.I would check to make sure the wiring to the fuel flow transducer and back to the JPI is sound. What it looks like is a loose connection. If that checks out, it probably is a transducer issue. Sent from my iPhone using Tapatalk Pro 1 Quote
larrynimmo Posted January 11, 2022 Report Posted January 11, 2022 I have the exact same issue….about 450 hours on the JPI installation….will check connections, but am prepared to change the transducer 1 Quote
ArtVandelay Posted January 11, 2022 Report Posted January 11, 2022 I have the exact same issue….about 450 hours on the JPI installation….will check connections, but am prepared to change the transducer Before you do that, disconnect the transducer, spray inside liberally with carburetor cleaner, connect it back up, see if that fixes it. The impeller could be sticking. 1 Quote
carusoam Posted January 11, 2022 Report Posted January 11, 2022 Varying that quickly, looks like it is not counting the turns of the sensor very well… typical of a loose connection dropping blips… If it were reading high… expect an air leak entering the system… be on the look out for blue stains… (to get cyclic behavior, something would have to alter the air leaking in…) If reading low… expect gum in the sensor… the fuel additives tend to build up slowing the revolutions down… (not usually cyclic behavior) Is it reading the right number at the peak of its cyclic behavior? Or is the peak number incorrect? Of course this could be electronic noise as well… if this is the challenge…. Expect chasing grounds to be helpful… Engine monitors have a challenge of having wires going from the engine to the instrument panel… with wires that get run close to the ignition system… PP thoughts only, -a- 1 Quote
larrynimmo Posted January 13, 2022 Report Posted January 13, 2022 One wire was broke off…second wire broke as I unplugged it 1 Quote
Marauder Posted January 13, 2022 Report Posted January 13, 2022 One wire was broke off…second wire broke as I unplugged itWell that is a problem. Sent from my iPhone using Tapatalk Pro Quote
PT20J Posted January 13, 2022 Report Posted January 13, 2022 2 hours ago, larrynimmo said: One wire was broke off…second wire broke as I unplugged it Looks like someone didn't install the pins correctly -- probably didn't have the correct crimp tool and soldered them without crimping down the strain relief ears onto the insulation. It is always best to crimp pins, but soldering is acceptable if care is taken not to allow the solder to wick up the wire past the strain relief which really needs to be crimped in any case. 1 Quote
larrynimmo Posted January 13, 2022 Report Posted January 13, 2022 Absolutely right Skip….I made connections myself wit AI watching and I did heat shrink to stress relieve…all good noe 1 Quote
jaylw314 Posted January 13, 2022 Report Posted January 13, 2022 45 minutes ago, PT20J said: Looks like someone didn't install the pins correctly -- probably didn't have the correct crimp tool and soldered them without crimping down the strain relief ears onto the insulation. It is always best to crimp pins, but soldering is acceptable if care is taken not to allow the solder to wick up the wire past the strain relief which really needs to be crimped in any case. Oof, you're right, the insulation doesn't have those grab marks. I'd say in a high-vibration environment, crimping with heat shrink is ALWAYS better than soldering, at least that's the message I've gotten in a couple EAA workshops. Proper crimping should produce a gas-tight interface in the connection and will prevent corrosion in the appropriate place as well as soldering, with much less worry about stress fatigue. 1 Quote
carusoam Posted January 14, 2022 Report Posted January 14, 2022 Great follow up Larry! The pic is invisible to my iPad… But I sensed it was there… See if this helps any… Tis better to have FF data than to not have FF data…. -a- Quote
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