N6018Q Posted June 26, 2018 Report Posted June 26, 2018 Mechanic performed a “cup test” on my injector lines today (not through the injectors). The amounts shown are what he got by running the boost pump for 60 seconds with full throttle and mixture. Seems like about 2 ounces or so in each bottle. Is that a normal amount? We disconnected the fuel line before the servo and the boost pump produced about 1 gallon in 60 seconds.
kortopates Posted June 26, 2018 Report Posted June 26, 2018 Generally, or perhaps I should say most commonly, the intent of this test is to verify all the cylinders are getting an even amount of fuel relative to each other. Its not so much the volume but that the height or volume of all the bottles is very close to one another. Without gami or position tuned injectors they should be very even and to test for that its more commonly done with the fuel injectors on first - unless one was really expecting clogged fuel divider was altering the fuel but typically one would try that after finding the fuel flow was not evenly distributed and the try it without the injectors to attempt to isolate it between the divider output and the injectors.
Guest Posted June 26, 2018 Report Posted June 26, 2018 (edited) With no airflow through the servo the fuel delivery to the flow divider will also be quite low. Clarence Edited June 26, 2018 by M20Doc
N201MKTurbo Posted June 26, 2018 Report Posted June 26, 2018 The oriface in the injectors is what determines the flow. The test you did means nothing. Even if you did it with the nozzles on the injector lines, you would need a good graduated cylinder to measure the differences we see on our EGT scanners. I was having poor mixture dostribution for the last year or so, which didn’t use to be the case. My GAMI spread used to be within 0.2 GPH. It was running 1.2 GPH lately. I decided to get to the bottom of it. I took the nozzles to the inspection shop at work and asked if they could measure the orifices in the nozzles. He pulled out his collection of gage pins and started running them through. The biggest one would take an oversized 0.027 (0.0272) pin. The tightest one would only take an undersized 0.026 (0.0258) pin. I looked at all of them under the microscope and was able to focus all the way down the orifice bore. They all looked clean. I took the 0.0272 pin and tapped it through all bores. Two of them extruded a perfect cylinder of varnish. After this I inspected them under the microscope again and there was no metal damage at all. In fact the inside of the bores look amazingly good. Well, my engine is back to its old self again and will run smooth down to 7.8 GPH LOP. I’ve never used Hopps #9 and at this point I’ll never know if it would have cleaned it out, but the old school method of soaking them in MEK seems to have let me down.
N6018Q Posted June 26, 2018 Author Report Posted June 26, 2018 29 minutes ago, N201MKTurbo said: The oriface in the injectors is what determines the flow. The test you did means nothing. Yeah I got that from the two previous answers. I also got an analysis today from Savvy that indicates probable injector blockage AND servo malfunction. My mechanic is sending out the injectors, servo and the the distributor for testing and overhaul/replacement as necessary. It’s interesting that the “tried and true” method with MEK was ineffective.
carusoam Posted June 26, 2018 Report Posted June 26, 2018 18Q, You can also search for this test under various names like baby food jar test... Also look up hopps #9 and ultrasonic cleaners... These are the things that go with getting a blocked injector... (look that up too) Testing lines without injectors would possibly test a blockage... but it would have to be quite large to show up... and the injectors are where the blockage usually occurs... Wait a minute... why was your mechanic setting up this test? What do you know already? You have a really interesting audience here. Mechanics, engine instrument guru, an engineer, and others... What did you send to Savvy? Do you have the charts that they produce? Or JPI graphs of any sort? I was thinking you are testing your boost pump... kind of what your post title was indicating. PP thoughts only, not a mechanic...or an engine instrument guru... Best regards, -a-
N6018Q Posted June 26, 2018 Author Report Posted June 26, 2018 9 hours ago, carusoam said: why was your mechanic setting up this test? What do you know already? What did you send to Savvy? Do you have the charts that they produce? Or JPI graphs of any sort? I started a thread back in April about engine roughness at 2400 RPM. The MS consensus back then was that it was probably my fuel servo. I relayed that info to the local mechanic but he was convinced it was an electrical issue. I was pretty confident that it wasn't, since I just got the plane out of an annual which included a new harness and spark plugs and magneto overhauls. He found a cracked magneto and a harness that was jumping fire to the frame (that's probably not the technical terminology but I'm not a mechanic). Last week he completed the installation of a JPI 830, along with another new harness and re-overhauled magnetos. Run-ups seemed fine but whenever I got on the runway and applied full power, the engine immediately started stumbling. A mea culpa here: I had leaned a bit for ground operations at the 2000' airport I'm located at right now. This after reading here about the probability of fouling plugs at full rich. I didn't go full rich on that take-off attempt. ( I know that right now a bunch of readers are shaking their heads and wondering what kind of idiot does that.) After this was pointed out by @kortopates, I went back Monday morning to see if that was all that was wrong. It wasn't. The engine exhibited roughness at all RPM's no matter what the mixture was set at. The mechanic was finally convinced that it had a fuel issue. To his credit, he did a great job installing the JPI and found the issues with the electrical system that could have bitten me down the road. The tests we did was to try to isolate which component of the fuel system was bad. I also sent the data from the last run-up to Savvy and @kortopates indicated probable servo issue and injector blockage. The servo inlet filter had a small amount of trash in it. The attached pic that looks like a halfway normal run-up was from Friday. The erratic pic is from Monday.
carusoam Posted June 27, 2018 Report Posted June 27, 2018 I’m glad you connected the threads together... and described the back ground. I’m not a mechanic either... but even a mechanic needs the whole story to give his best answer... If I understand your graphs... they only contain a few minutes of run time.... but one EGT is not following very closely to the others... The guys at Savvy have a few guidances that, when followed, can be helpful to running tests and collecting data... The normal MS stuff... (not sure you described your experience the way I understood it...) 1) lean from start-up to taxi... 2) full rich for run-up and T/O... 2.5) if you accidently stay lean, the engine will stumble... go back to the beginning of the runway and start again, full Rich this time. 3) unless you are not near sea level... then use target EGT... (are you familiar?) this is a procedure for developing max hp at your airport’s altitude... (if it isn’t close to SL) 4) There isn’t enough room for experiments on a 2,000’ runway... (I can’t be more helpful here) 5) Plan A: be off the ground at the halfway point... Plan B: be stopping as best you can... (private pilot training) 6) looking at the JPI graph... do you see anything standing out? 7) Describe what you were doing during this time sequence? I see the engine responding to throttle position with increases/decrease in FF and a delayed (normal) response in EGT... something going on with EGT number 2 as it is a bit higher than the rest for some reason... 8) To generate some really usable data go to the Savvy website. 9) go ahead and continue to discuss your plans. The really short runway should be a solid part of the plan. Sorry for covering the same things twice... it’s a little circular, and not very helpful... Private Pilot thoughts only, not a Mechanic... or CFI... Best regards, -a-
carusoam Posted June 27, 2018 Report Posted June 27, 2018 Looking the third time... i see the junk... good to have it cleaned out... i see two erratic graphs that both follow the erratic throttle position... not really erratic. They just look like somebody moved the throttle a few times... The graph showing FF at 3gph isn’t going to be very helpful... The graph showing what appears to be a run-up where FF is 15gph is much more helpful... Do you want to describe your run-up procedure? Remind us if you can... How much time you have flying this M20E? Is it new to you? Trying to be helpful, just a bit rough around the edges... Best regards, -a-
N6018Q Posted June 27, 2018 Author Report Posted June 27, 2018 In the interest of brevity, I sacrificed conciseness and necessary detail. The 2000' I was referring to was MSL. The longer of the two runways at KWWR, where my plane is residing, is over 5500' long. There is a shorter one (2500') but I have no interest in using it until I know my plane is running reliably. The plane is new to me. I bought it in the November timeframe of 2017 but immediately started an annual that lasted until April this year, due to the mechanic only working on it after his regular work hours. I have ~130 hours since my PPL in 2016, almost all in Cessnas. Throughout all the insurance, FAA (and personal) required complex training, the engine ran beautifully. On the last flight with the CFI before his endorsement, the engine exhibited roughness when I was about 2 miles out on a straight in final. Since then the problem has been very intermittent in ground operations. Only after all the rework described above on the electrical system, along with the JPI install, did I feel confident enough to attempt a take off last week. My Friday runup was by the checklist (except for the full rich item). The second one on Monday (indicated by the erratic graph I posted earlier) was not part of a takeoff attempt. I started the plane at the hangar and was just trying to see whether my previous mistake of not going full rich was the only problem. This time, the engine was rough across the rpm spectrum. That's when the mechanic and I started the flow tests to try to identify faulty components. My understanding is lacking with regard to the "normal MS stuff" items 1 through 5, because if I understand you correctly, number 3 indicates "target EGT" while I am still on the runway (I am at 2000' MSL with a typical DA over 4000' at this time of year in NW Ok). This appears (to me) to contradict number 2 "full rich ". I'm familiar with leaning for cruise and have studied the EGT/CHT/BHP/BSFC graphs, so with a little time (and a smooth engine) I will be able to identify a EGT temp for max HP. Should I lean for that target BEFORE takeoff? With that being said, I do understand that I was leaned entirely too much for my Friday attempt. And for the record, even though I have my complex endorsement, I have scheduled additional training when my plane is running again. 1
Marauder Posted June 27, 2018 Report Posted June 27, 2018 In the interest of brevity, I sacrificed conciseness and necessary detail. The 2000' I was referring to was MSL. The longer of the two runways at KWWR, where my plane is residing, is over 5500' long. There is a shorter one (2500') but I have no interest in using it until I know my plane is running reliably. The plane is new to me. I bought it in the November timeframe of 2017 but immediately started an annual that lasted until April this year, due to the mechanic only working on it after his regular work hours. I have ~130 hours since my PPL in 2016, almost all in Cessnas. Throughout all the insurance, FAA (and personal) required complex training, the engine ran beautifully. On the last flight with the CFI before his endorsement, the engine exhibited roughness when I was about 2 miles out on a straight in final. Since then the problem has been very intermittent in ground operations. Only after all the rework described above on the electrical system, along with the JPI install, did I feel confident enough to attempt a take off last week. My Friday runup was by the checklist (except for the full rich item). The second one on Monday (indicated by the erratic graph I posted earlier) was not part of a takeoff attempt. I started the plane at the hangar and was just trying to see whether my previous mistake of not going full rich was the only problem. This time, the engine was rough across the rpm spectrum. That's when the mechanic and I started the flow tests to try to identify faulty components. My understanding is lacking with regard to the "normal MS stuff" items 1 through 5, because if I understand you correctly, number 3 indicates "target EGT" while I am still on the runway (I am at 2000' MSL with a typical DA over 4000' at this time of year in NW Ok). This appears (to me) to contradict number 2 "full rich ". I'm familiar with leaning for cruise and have studied the EGT/CHT/BHP/BSFC graphs, so with a little time (and a smooth engine) I will be able to identify a EGT temp for max HP. Should I lean for that target BEFORE takeoff? With that being said, I do understand that I was leaned entirely too much for my Friday attempt. And for the record, even though I have my complex endorsement, I have scheduled additional training when my plane is running again. I think I followed your thread correctly. Based on the JPI data you posted, you have something going on with the #2 cylinder. It really appears to be running on one plug. My EGTs are fairly consistent with each other during run up (I will find and post one of them). As for your leaning question, there should be no reason to lean your airplane for takeoff at a 2000’ MSL airport. Granted on a really hot day, the density altitude will be much higher, but anything around 2000’ to 3000’ feet shouldn’t need to be leaned.It doesn’t sound like you have flown it, so doing an inflight mag check was done.Sent from my iPad using Tapatalk Pro 1
N6018Q Posted June 27, 2018 Author Report Posted June 27, 2018 35 minutes ago, Marauder said: As for your leaning question, there should be no reason to lean your airplane for takeoff at a 2000’ MSL airport. Granted on a really hot day, the density altitude will be much higher, but anything around 2000’ to 3000’ feet shouldn’t need to be leaned. It doesn’t sound like you have flown it, so doing an inflight mag check was done. Thanks! And no, I haven't done an in-flight mag check yet. My servo, injectors and distributor are all out for testing right now but I have downloaded the Savvy suggested flight profile and will implement it ASAP. 3
kortopates Posted June 27, 2018 Report Posted June 27, 2018 We'll have to wait for the fuel injection specialist to bench test your servo and let you know what caused the issue. But its likely the same debris you found in the fuel divider is responsible for gumming up internals of the servo's and significantly reducing its ability to precisely meter fuel. That's my guess any way. As mentioned via savvy, its still potential concern to make sure there isn't any more of this stuff upstream that could cause further havoc after you re-install the fuel components. If I am right about the debris being the issue, knowing what the debris material is is and its likely source could prove valuable. But you'll find out soon enough what the fuel guys learns and he too may have some suggestions on that. 1
N6018Q Posted June 27, 2018 Author Report Posted June 27, 2018 1 hour ago, kortopates said: We'll have to wait for the fuel injection specialist to bench test your servo and let you know what caused the issue. But its likely the same debris you found in the fuel divider is responsible for gumming up internals of the servo's and significantly reducing its ability to precisely meter fuel. That's my guess any way. As mentioned via savvy, its still potential concern to make sure there isn't any more of this stuff upstream that could cause further havoc after you re-install the fuel components. If I am right about the debris being the issue, knowing what the debris material is is and its likely source could prove valuable. But you'll find out soon enough what the fuel guys learns and he too may have some suggestions on that. Yes sir on the upstream checking. My mechanic is doing that now. I just had my boost pump overhauled in April due to a leaking tell-tale. The largest particle of fibrous debris in the servo inlet screen looked suspiciously like a piece of shredded synthetic impeller from the leaking pump. Visual inspection of the injector nozzle ID's, particularly #2, also indicated the presence of debris. 1
kortopates Posted June 27, 2018 Report Posted June 27, 2018 4 minutes ago, N6018Q said: Yes sir on the upstream checking. My mechanic is doing that now. I just had my boost pump overhauled in April due to a leaking tell-tale. The largest particle of fibrous debris in the servo inlet screen looked suspiciously like a piece of shredded synthetic impeller from the leaking pump. Visual inspection of the injector nozzle ID's, particularly #2, also indicated the presence of debris. That's great news and a very plausible explanation for all this grief. Considering the aux pump has been replaced its even better news that this should be all behind you once its all cleaned up. 1
carusoam Posted June 28, 2018 Report Posted June 28, 2018 18Q, You confused me... (my fault) Use the words MSL... 2000’msl. Mean Sea Level... to denote altitude. I assumed runway length 2000’... way too short to have an engine challenge and attempting a T/O.... Since we are talking warm temps of summer and T/Os... and a great new to U plane... Have you calculated T/O length using gross weight and the Density altitude (DA)? My friend Patrick always reminds me of this when conversing with new owners... An important detail when you get away from the long runway and use a 2,000’ long runway... Best regards, -a-
N6018Q Posted June 28, 2018 Author Report Posted June 28, 2018 @carusoam sorry about that. Yes, I’ve looked at my charts. Today for example, the DA was 5200’. Highest temp shown is 80 degrees F with a 1330’ roll. Today it was about 100 degrees. I would reserve no less than 1500’ for takeoff, it’s pretty flat here, no 50’ obstacles. I wouldn’t have any reservations about using the 2500’ runway AFTER I’m confident in my engine’s reliability. The crosswinds here near the Oklahoma panhandle can be brutal and I would normally use the 23-05 runway instead of the 17-35 runway if the winds dictated. My initial ppl training, which took almost two years due to work constraints consisted of flying on very cold and very hot days and one of the things I really noticed was the difference DA made on takeoffs in the underpowered 172 I was using. I do appreciate the heads up, and don’t want to give the impression that I know it all. The main reason I signed up on this forum is to take advantage of the wealth of info shared here. I want to be a better pilot and am willing to listen to anything you have to say. 1
carusoam Posted June 28, 2018 Report Posted June 28, 2018 Read on, my friend... There is so much experience in every thread. mostly first hand kind of stuff. Often by very experienced pilots. Sometimes some spooky stories... Sometimes some funny stories. Use the search function often. It takes some practice to find exactly what you are looking for. one oddity you might be interested in... in this past year we had an MSer fly around the world. In the middle of his trip he acquired some bad fuel. It was contaminated with some stringy rubbery looking material. He was able to recognize the problem and get back on the ground. An interesting story about fuel contamination and how it might look similar to what you are seeing... but for a completely different reason... Enjoy MS... Find the threads like... ‘introduce yourself’ and ‘today’s flight’ Great place to read about MSers... and write about your Mooney experience... some threads are near a decade aged our youngest MSers aren’t very young anymore... If it gets really hot where you are... look up traveling to the arctic circle... Some videos by an MSer who flew North... Everyone is welcome here. Best regards, -a-
Yetti Posted June 28, 2018 Report Posted June 28, 2018 A couple of things in scanning the thread. Check the finger screen on the servo. again. There is supposed to be a filter just past the fuel pump. Most people don't know about. Check it. When were the mags done last. Check your plugs again. at 5000 DA you can over richen as I found out in Midland. Do you know how to burn the plugs off? The aggressive lean while taxi is different at 5000 DA than at sea level. I got used to putting the mixture at a certain place. It should be less for 5000 DA.
N6018Q Posted June 28, 2018 Author Report Posted June 28, 2018 1 hour ago, Yetti said: There is supposed to be a filter just past the fuel pump. Most people don't know about. Check it. The one attached to the boost pump? or is there another past the engine driven and before the finger screen in the servo? if you're referring to the boost pump filter, yes, we are checking that one. When were the mags done last. Mags were overhauled twice in the last 3 months. Obviously the first time a sub par job was done. Check your plugs again. Yes, that's my mechanic's SOP Do you know how to burn the plugs off? My understanding is that's what aggressive leaning for ground operations does. Is there more to it than that? The aggressive lean while taxi is different at 5000 DA than at sea level. I got used to putting the mixture at a certain place. It should be less for 5000 DA. "less" as in leaner?
Yetti Posted June 28, 2018 Report Posted June 28, 2018 Do you know how to burn the plugs off? My understanding is that's what aggressive leaning for ground operations does. Is there more to it than that? The aggressive lean while taxi is different at 5000 DA than at sea level. I got used to putting the mixture at a certain place. It should be less for 5000 DA. "less" as in leaner? If the plugs are fouled on the ground you can run the engine at say 1700 RPMs Then watch the EGT and reduce mixture and run where you would normal flying EGT for a few minutes and it will burn the fouling off the plugs. Yes leaner. taxi lean for mine is about 1/4 Mixture. At 5000 DA taxi lean was about 1/8 mixture. You may also want to check the fuel servo and make sure no FOD has been ingressed. Your fuel servo may also be on the fritz. Also may want to check for induction leaks. Especially cylinder 2. Smoke test. 1
ArtVandelay Posted June 28, 2018 Report Posted June 28, 2018 Taxi Fuel flow should be about 1.5gph and 1000rpm. If you much higher FF it’s probably too rich. 1
RobertGary1 Posted June 28, 2018 Report Posted June 28, 2018 This is the more typical test. Compare flow between the injectors. -Robert 2
jetdriven Posted June 28, 2018 Report Posted June 28, 2018 On 6/25/2018 at 9:52 PM, M20Doc said: With no airflow through the servo the fuel delivery to the flow divider will also be quite low. Clarence I’ve done this test and full rich full throttle it’s 7.2 GPH or so. Or 3.84oz per injector line per minute. Not much.
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