Peter Rejto Posted June 14, 2021 Report Share Posted June 14, 2021 At my annual on my '78 J in early May I complained of a fuel smell in the cabin mostly on left side. Small leak was identified and repaired at fuel sender on right side. Problem not fixed and I continue to notice a fuel smell and I think a decrease in left tank fuel level after sitting for a couple of weeks though no fuel staining on hangar floor. I do notice a small stain at a drain hole but zero staining on any rivet lines or places that are tank seal joints. Until recently my Shadin fuel totalizer has been quite steady in readings fluctuating perhaps .1 gph occasionally. Starting with my most recent 8 hour trip the Shadin will not settle down and fluctuates between 9.7 to 10.5. Turning on the boost pump sometimes reduces flow and sometimes the Shadin will be steady for 15-20 min and then start fluctuating. I'm thinking that air must be getting into the fuel line and this might be related to the fuel smell. Yesterday, departing Adelaide, I had a brief stumble. The stumble continued in cruise at 5,000' every 15-20 min. I was probably leaned to 50 ROP. This was on left tank. I switched to right tank and thought initially the problem was gone, but it returned though less frequently. Later I climbed to 8,000 and didn't lean as aggressively, more like 100 ROP and I got a single hiccup in 1.5 hours. At the annual my left mag was replaced with a Surefly (with timing). Initial flights have been perfect until the trip yesterday. I'm really unsure what the problem is....fuel or Surefly. Up until yesterday I've had zero issues with this less than mid time engine. Obviously I'm in touch with my mechanic but he isn't located very close to home base. Any advice gratefully appreciated! Peter Quote Link to comment Share on other sites More sharing options...
PT20J Posted June 15, 2021 Report Share Posted June 15, 2021 Surefly stumble is a known issue with some 28V systems but yours should be 12V. If it happens again I suggest trying running on each mag alone for a while to see if you can isolate it. However, given your Shadin indications, I would suspect a fuel issue. I have a Shadin and an EDM 700 both connected to the same Floscan transducer. The Shadin is much better damped than the EDM. So, if the Shadin is dancing around, I would suspect something fairly drastic is going on. It sounds like perhaps you are getting air in the system and wherever this is coming from might also leak fuel causing the odor. Skip 2 Quote Link to comment Share on other sites More sharing options...
KSMooniac Posted June 15, 2021 Report Share Posted June 15, 2021 Two suggestions... Drop a liberal amount of oil on the fuel selector switch/shaft. You might be getting air in through it. Second, take off the bottom panel where the electric fuel pump lives and inspect the lines and look for staining. I had a line loosen behind the firewall and had symptoms you describe. Sent from my LM-V405 using Tapatalk 3 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 15, 2021 Report Share Posted June 15, 2021 Aroma of fuel leaking… when the plane is parked, fuel gets out… Eratic FF data comes from excess material flowing in the fuel line… The same ‘hole’ that allows fuel out while parked… allows air in while running… air is the excess material being counted… If the FF number is drifting higher… the amount of air getting in is increasing… The fuel system is pretty good about separating fuel and air…. But, if you are getting a skip… that could be a lot of air…. If fuel is going missing… there are blue stains somewhere…. Time to go find them…. If there isn’t enough leaked out…. It is possible to see air bubbles in the fuel line… Disconnecting the fuel line near the engine and running the electric pump has found air entering from the fuel selector switch a few times around here… If you have a leak at the fuel selector switch you might notice a blue stain there as well… There shouldn’t be a blue stain at the fuel selector switch… Do some blue stain hunting, grab some pics… let’s see what you got. PP thoughts only, not a mechanic… Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted June 15, 2021 Report Share Posted June 15, 2021 Is your fuel pressure steady? Quote Link to comment Share on other sites More sharing options...
EricJ Posted June 15, 2021 Report Share Posted June 15, 2021 Next time it does it do an in-flight mag check.   Quote Link to comment Share on other sites More sharing options...
Peter Rejto Posted June 15, 2021 Author Report Share Posted June 15, 2021 Thanks for all the suggestions! Yes, fuel pressure seems quite steady. I have been hesitant to do a mag check in flight after reading about typical loud backfires. My wife was on board yesterday so my hesitancy was tripled! In my first post I didn’t mention that the left mag (Surefly) drops 25 RPM but the Slick Right, 100+. My POH indicates 100+ is okay but also indicates that they ought not to differ by more than 50 RPM. Is this still a valid statement with a Surefly installed? I will certainly inspect for more fuel staining, check the fuel selector and boost pump fittings. Thanks! Peter Quote Link to comment Share on other sites More sharing options...
takair Posted June 15, 2021 Report Share Posted June 15, 2021 4 hours ago, Peter Rejto said: Thanks for all the suggestions! Yes, fuel pressure seems quite steady. I have been hesitant to do a mag check in flight after reading about typical loud backfires. My wife was on board yesterday so my hesitancy was tripled! In my first post I didn’t mention that the left mag (Surefly) drops 25 RPM but the Slick Right, 100+. My POH indicates 100+ is okay but also indicates that they ought not to differ by more than 50 RPM. Is this still a valid statement with a Surefly installed? I will certainly inspect for more fuel staining, check the fuel selector and boost pump fittings. Thanks! Peter Scott might be on to something (fuel valve).  If flow is erratic and the problem occurs in climb, you may be pulling air.  Have seen a leak in the gascolator gasket cause similar issue….without staining.  It would just draw some air.  Do you know if they had the gascolator apart at annual?  Does not really sound electronic ignition related.  1 Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted June 15, 2021 Report Share Posted June 15, 2021 10 hours ago, Peter Rejto said: Thanks for all the suggestions! Yes, fuel pressure seems quite steady. I have been hesitant to do a mag check in flight after reading about typical loud backfires. My wife was on board yesterday so my hesitancy was tripled! In my first post I didn’t mention that the left mag (Surefly) drops 25 RPM but the Slick Right, 100+. My POH indicates 100+ is okay but also indicates that they ought not to differ by more than 50 RPM. Is this still a valid statement with a Surefly installed? I will certainly inspect for more fuel staining, check the fuel selector and boost pump fittings. Thanks! Peter If you do an inflight mag check with the SF, pull back the power before switching from the mag to the SF.  The bang at full power is annoying, but pulled back, much better. 1 Quote Link to comment Share on other sites More sharing options...
A64Pilot Posted June 15, 2021 Report Share Posted June 15, 2021 14 hours ago, Ragsf15e said: Is your fuel pressure steady? This is the important question to see if it’s air being sucked in, next time it stumbles look. Quote Link to comment Share on other sites More sharing options...
Yetti Posted June 18, 2021 Report Share Posted June 18, 2021 There have been a couple of these type stumbles where it was a broken oil ring on one cylinder.  Do the mag checks as above and pull the plugs to see if they tell a story Quote Link to comment Share on other sites More sharing options...
DCarlton Posted June 18, 2021 Report Share Posted June 18, 2021 I experienced a similar illusive issue several years ago. Since then my engine has been overhauled. Between those first two sentences is a novel of in flight experience and troubleshooting. I'm curious when you say stumble, if it was an unusual 1-2 sec miss (a brief hiccup), or a more lengthy period of erratic operation. Quote Link to comment Share on other sites More sharing options...
Peter Rejto Posted June 20, 2021 Author Report Share Posted June 20, 2021 On 6/18/2021 at 3:44 PM, DCarlton said: I experienced a similar illusive issue several years ago. Since then my engine has been overhauled. Between those first two sentences is a novel of in flight experience and troubleshooting. I'm curious when you say stumble, if it was an unusual 1-2 sec miss (a brief hiccup), or a more lengthy period of erratic operation. The "stumble" was/is extremely brief and solitary. It lasts a fraction of a second and repeats every 15/20 min, or with different altitude/leaning maybe once every 1.5 hours. UPDATE: Yesterday i had the opportunity to dig into this. 1. The Surefly (Slick) cap over the ignition harness wires lost all three hold down screws! The cap was just hanging on the 4 leads with all screws lost. I've managed to find a single replacement screw and it took me an hour to get that one screw back in place. I doubt I'm capable of getting the other 2 screws back without removing obstacles as working space is nil. 2. I pulled the 4 plugs operated by the left mag (Surefly) Top #3,#1, botton #2,#4. All plugs look normal except the bottom plug of #4 was quite oiled, black and has a lead ball. This is just 12 hours since annual where no such symptom was noted. I pulled the top plug of #4 and fortunately it is completely normal. Hopefully this points to either a failed plug or failed lead. I did measure the resistance of the bottom #4 plug and it is 1,250 ohms. I know, not a reliable test, but at least under no load it seems like the plug ought to fire. So, maybe it's the ignition lead. Anyway, I think I'm getting close to finding the issue! Thanks, Peter 1 Quote Link to comment Share on other sites More sharing options...
Mcstealth Posted June 20, 2021 Report Share Posted June 20, 2021 Now that is troubling. Four screws failing, not just one. Quote Link to comment Share on other sites More sharing options...
PT20J Posted June 20, 2021 Report Share Posted June 20, 2021 22 minutes ago, Mcstealth said: Now that is troubling. Four screws failing, not just one. Sounds more like someone forgot to tighten the screws. 4 Quote Link to comment Share on other sites More sharing options...
Guest Posted June 21, 2021 Report Share Posted June 21, 2021 You could perhaps believe that one screw failed, but all three would be harder to believe. Clarence Quote Link to comment Share on other sites More sharing options...
Peter Rejto Posted June 21, 2021 Author Report Share Posted June 21, 2021 It is all very strange. I have managed with great difficulty to reinstall 2 of the 3 screws. I think the 3rd is beyond my capabilities! What remains to be determined is why I have the fouled plug in the #4 bottom cylinder. Plug or ignition lead, or worst case a cylinder problem? Perhaps the loose cap allowed the #4 lead to pull out a bit? I wasn't able to tell given the cramped working space. Once I get the plugs back in hopefully a runup/mag check will reveal something. Peter Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 21, 2021 Report Share Posted June 21, 2021 Is there any JPI or other engine data available to look at? Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Peter Rejto Posted June 21, 2021 Author Report Share Posted June 21, 2021 (edited) 5 hours ago, carusoam said: Is there any JPI or other engine data available to look at? Yes and no, or maybe. I have an older EI unit and I've had a devil of a time trying to retrieve the available data let alone display it. If the problem persists I may need to resort to it. I finished up today. The run-up / mag checks were entirely normal. I won't be able to fly until next week. I spoke with my mechanic and he insists that he torqued all three screws, but also noted that on other Surefly installations he has had screws come out but never more than 1. I cannot believe that such a critical part of the aircraft depends on three garden variety screws with no means of lock wiring them into place. Replacing the screws properly will take many hours of work and I have little trust that they will remain in place. Has anyone else at MooneySpace had an issue with these screws? Peter Edited June 21, 2021 by Peter Rejto Quote Link to comment Share on other sites More sharing options...
Peter Rejto Posted June 21, 2021 Author Report Share Posted June 21, 2021 I wrote to Surefly about the problem. I'll paraphrase their reply. 1. Most likely I've solved the problem. 2. This is the first report they have heard about screws coming loose. Peter Quote Link to comment Share on other sites More sharing options...
David Lloyd Posted June 21, 2021 Report Share Posted June 21, 2021 Safety wire, locktite, lock nuts, torque wrenches and torque screwdrivers all to keep stuff under the cowling from backing off. Yet the mag cap screws, nothing special and airplanes aren't falling out of the sky left and right. I think once I had a magneto with one of those screws missing. Same cap and screw arrangement on Slick, Bendix and Surefly. Never actually seen anyone torque these screws with any measuring device. Don't think they were tight at first and won't happen again. Quote Link to comment Share on other sites More sharing options...
Guest Posted June 21, 2021 Report Share Posted June 21, 2021 13 hours ago, Peter Rejto said: Yes and no, or maybe. I have an older EI unit and I've had a devil of a time trying to retrieve the available data let alone display it. If the problem persists I may need to resort to it. I finished up today. The run-up / mag checks were entirely normal. I won't be able to fly until next week. I spoke with my mechanic and he insists that he torqued all three screws, but also noted that on other Surefly installations he has had screws come out but never more than 1. I cannot believe that such a critical part of the aircraft depends on three garden variety screws with no means of lock wiring them into place. Replacing the screws properly will take many hours of work and I have little trust that they will remain in place. Has anyone else at MooneySpace had an issue with these screws? Peter There are literally thousands upon thousands of Slick magnetos out there with the same 3 screws holding the harnesses on and they aren’t falling off.  Strange that your maintainer is having issues that no one else is having. Clarence Quote Link to comment Share on other sites More sharing options...
Peter Rejto Posted June 22, 2021 Author Report Share Posted June 22, 2021 I don't disagree with any of the comments re screws. I was just reporting what has been said to me. Nonetheless, it is disconcerting to have experienced this! I will probably remove the top cowling and check screw tightness after a few hours of flight. In any case I've yet to diagnose the fuel flow issues that remain. I certainly have appreciated all the feedback! Peter Quote Link to comment Share on other sites More sharing options...
Marauder Posted June 22, 2021 Report Share Posted June 22, 2021 Yes and no, or maybe. I have an older EI unit and I've had a devil of a time trying to retrieve the available data let alone display it. If the problem persists I may need to resort to it. I finished up today. The run-up / mag checks were entirely normal. I won't be able to fly until next week. I spoke with my mechanic and he insists that he torqued all three screws, but also noted that on other Surefly installations he has had screws come out but never more than 1. I cannot believe that such a critical part of the aircraft depends on three garden variety screws with no means of lock wiring them into place. Replacing the screws properly will take many hours of work and I have little trust that they will remain in place. Has anyone else at MooneySpace had an issue with these screws? Peter I would try the EI guy who visits the site periodically to see if you can get the EI data (his call sign Oregon87 or something similar). I had a very similar thing happen and using the JPI data with a 1 second scan, the Savvy people (Paul) were able to see periodic spark plug failures. Could be a reason your #4 has more oil on it. I would have never narrowed it down without the engine analyzer data. Having it stumble does catch your attention, doesn’t it?Sent from my iPad using Tapatalk Pro 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 22, 2021 Report Share Posted June 22, 2021 29 minutes ago, Marauder said: I would try the EI guy who visits the site periodically to see if you can get the EI data (his call sign Oregon87 or something similar). I had a very similar thing happen and using the JPI data with a 1 second scan, the Savvy people (Paul) were able to see periodic spark plug failures. Could be a reason your #4 has more oil on it. I would have never narrowed it down without the engine analyzer data. Having it stumble does catch your attention, doesn’t it? Sent from my iPad using Tapatalk Pro Hey… are you up early or late?  +1 For getting data to Savvy…. +1 For a different screwdriver holder… it appears the one holding your screwdriver currently isn’t working out very well… Lets see if @oregon87is around… He is our best resource for EI knowledge… Best regards, -a-  Quote Link to comment Share on other sites More sharing options...
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