This is a good point to ask the question, what DOSE cause a jug of fuel to go bad??? I have been flying C/L stunt regularly since 1986 or so, and flew smaller stuff as a kid. I'm 69 years old and that gets close to 60 years of activity and experience. Since 1986 the volume of fuel in creased dramatically !! In all that time, I have only had one jug of fuel that "went bad" on me. it was the jug I mentioned in my previous post. half way through the jug at a flying session at Buder park, my turn comes up for a flight and the engine would not start. Didn't even want to pop and this was after three or four flights previously that day. tried all the usual stuff and a fresh jug of fuel solved the problem even with running the original plug. I eventually used up the suspect fuel during the planedemic by adding it a little at a time to known good fuel.
I don't know, for the most part. What I have seen of fuel issues are usually either wrong mixes for the engine, or some sort of contamination. In all cases I know about, the contamination was some sort of chemical that shouldn't have been there. I know of 3 really clear examples over the last 50ish years I have been doing this, and I only know for sure what the offending contaminant actually was.
Case 1 - 1995 Tri-Cities NATs. Everyone was using SIG fuel. For whatever reason, there were a bunch of people with engine issues, some to the point it damaged the engine, but lot of cases of strange runs, flameouts, and just "odd-sounding" exhaust notes. This included the first and only PA engine that appeared to eat itself up, destroying the connecting rod on David's shiny new PA40. We started trying to figure it out, and someone (maybe Mike Pratt) to some of the offending fuel back to SIG, but I never heard what if any problem they found. We did notice that there were clear globs of something floating around in it, it looked like heavy silicone oil, but could have been anything, we didn't test it. When we got back, we verified it woudn't run here, either, and gave our remaining stocks to some RC guys, it didn't run right for them, either, and I could recognize the same odd sound from 200 yards away. The said it was "too much oil". I never heard for sure what the actual cause was, but it somehow got fixed and we subsequently used SIG for a long time until we discovered the "tater" problem with PA61s and up, and switched to Powermaster.
Case 2 - shortly after the 95 NATS, we started looking for alternate fuel. Paul was using Red Max, and it was fine, and I got a few cases with no issues. Then, suddenly, I went to order it and got the "all castor is bad" story from the Red Max people. Since we never knew what caused SIG's issue, it might have been plausible. I got some of their fuel with the usual amount of castor, and sure enough, little white flakes precipitated out of it in a few weeks. I filtered it all out, few weeks later, same thing again. Also, I started having engine run issues with my PA40, with it randomly quitting on the test stand like you flipped a switch, perfect and then nothing. Start it right back up, run for while, same thing again 30 seconds later. Tried to fly it anyway, and first inside loop, ratty, second, super-ratty, third, stopped dead. In that case I grabbed a sample of the fuel and took it to the standards lab of "a large aerospace organization" and had it analyzed. Normal fuel components + abnormal amounts of Xylene. I did some research and found that Xylene is used to rinse castor beans to get the last little bit of oil out of the crushed remains. The oil is then heated to drive off the Xylene. I got some Xylene, put it in some SIG castor oil ,looked like a snowstorm. Regular SIG castor, no problems and no flakes, regular Powermaster castor, no problems and no flakes.
Red Max apparently got a bad batch of castor oil, probably because it was cheap "extracted" type, and instead of trying to diagnose and correct the issue, they saw an opportunity to market their super-duper secret oil for go-karts and were telling everyone that ALL castor was bad and the good kind was no longer available. This was a demonstrable lie, I told their "oil expert" exactly what the offending component was, they continued to lie about it. There are plenty of other places to get fuel (like JBK and Doug Taffinder, SIG, Powermaster, Byron) so I moved on.
So I started experimenting with various fuel sources, and additives. After an incredible amount of experimentation, I found that my flameout problem was completely solved by running Byron fuel, of all things. I cannot tell you how far down the list this was, I even tried Omega and Cool Power before I got down to Byron. Perfectly smooth, with a remarkably steady exhaust note. At the same time, other people had similar issues, and every time we tried Byron fuel, it went away. I ran several NATs with Byron in my 40VF, poured into a SIG jug to hold down the jokes.
During all this, I had a good flight until the middle of the 4-leaf, flamed out again, crashed my 95 NATS airplane a few days before we were going to leave for the 96 NATs.
Ultimately, there were three unrelated things going on - the bad SIG fuel batch, completely independently, my second PA40 had some still-undiagnosed flameout issue that I never was able to diagnose despite extensive experimentation, and apparently still did it when Randy got it back, and, on top of it, the "all castor is bad" lie from Red Max. We of course thought it was all part of a single issue, but in this case, it wasn't. Using different engines (40VF vice PA40), reputable fuel manufacturers (SIG and Taff), no more problems (until we got to the PA61 and the tater issue).
Case #3 Shortly before the 2008(?) WC, Paul Ferrell was test-flying his brand-new Infinity with a RO-Jett 61 BSE "Brett" version set up exactly like mine. He started having the "ratty inside loops" issue similar to but not as bad a my problems in late 95 early 96 PA40 issues, and it was clearly degenerating on every flight. After trying a few things, we checked the Powermaster batch number, and it was a new batch that none of us had tried. I got some of my fuel, we ran it on the ground, and it started out ratty, and slowly got better through the tank. Something was obviously getting deposited in the engine with his fuel, and running my fuel was removing it. We switched plugs, that greatly improved it but it still ran "odd" for a few more tanks, but getting progressively better. Eventually, it sounded about right and he flew it with my fuel, no problems, we checked the fuel batch number to see what Powermaster had shipped to whereever the WC was (France, maybe?), it was a different batch, and he flew finished second in junior, and had no more issues.
Note that the "slowly changing" with run time is also what happens when you change the oil content of the fuel, it takes maybe 5-6 flight for it to settle down after an oil type or quantity change. So I figure there was something odd with the oil. I posted the batch number on SSW, and everybody who had that batch also reported various odd issues with it. I have no idea what the actual problem might have been and we didn't try to hard to track it down. The fuel guy at Texas Allied Chemicals was usually pretty helpful and knowledgeable about it, but he didn't know of any intentional difference between this batch and any other.
I distinguish "bad" fuel from "wrong" fuel. I can go get some Powermaster GMA, or any other home-job 10/22 50-50 fuel, and my engine will run ratty on inside loops very reliably, switch back to 10/17 75-25, back to normal, I can add up to at least 5% KL-198 and it is still OK (although it runs much differently).
That's a super-detailed way of saying "I don't know", it's rare enough that it's sort of a series of random failures/problems that don't have a common cause. Of course "bad fuel" problems are swamped as far as engine problems go by the endless string of self-induced engine issues that you see here incessantly (grind/drill/port/head-gasket/needlessly fiddle) and seem to be completely intractable and insoluble.
Brett
Topic: Fuel Cap left off for about 3 hours (Read 4018 times)