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On 93405, I found that my caps would leak only on two occasions. First, in flight if I didn't have the wing caps on perfectly parallel with the centerline of the airplane, they would leak. Seems that the air would cause a vacuum while going along the side of the cap if the cap wasn't straight. Reach out and straighten the cap, and the leaking stopped. Second, almost anytime I was on the ground, or on final approach, with low throttle settings, she would leak out of the header tank. At low power settings, she would pump more fuel than the return line could handle. In flight, I never had that problem. On the ground I would just turn off the fuel line from the wing tanks. Once in the air, I'd turn them back on. If I forgot to do it, I'd soon be reminded as the fuel indicator would remind me in short order. I suspect the return line was somewhat obstructed or the header tank wouldn't have leaked at all. I can't imagine it would do any good to have any of the vents sealed off. If the cap seals were good enough, the resulting vacuum would have stopped the flow of fuel. The wing tanks could (theoretically) have enough vacuum to actually collapse inward if they didn't leak a little air. The header tank, with the absence of a vacuum causing pump, would simply stop flowing fuel. In all cases, I can't see the system functioning correctly without vents. Larry ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: "'Bob Saville '" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[email protected]>; <[EMAIL PROTECTED]> Sent: Monday, April 22, 2002 12:26 AM Subject: Re: [COUPERS-TECH] [COUPERS] 87 Octane Gas > ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- > > Pete. > > "to close off the main tank cap vents." > > What do you mean - closing the vent hole?? Please do not do that. > I too have all three tanks vented and even though my system has been converted to a later one (none > vented wing tanks) ,mysteriously it works only with vented caps. > Leave your system as it is! > Or am I getting something wrong here??? > > Hartmut > > Pete Thomson wrote: > > > ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- > > > > Good evening evryone. I have read with some interest the comments on vapor > > lock. I have vented gas caps on all 3 tanks and have been advised by the > > service memorandums, which I am slowly going through during my annual from > > hell,to close off the main tank cap vents. I would sure appreciate some > > feedback from all of you, do you have vented or unvented caps on wing tanks > > and or the nose tank? If you have closed the vents on the wing tanks, where > > does the air come from to take the place of the fuel? Thanks Alaska Pete > > > > -----Original Message----- > > From: Bob Saville > > To: [EMAIL PROTECTED] > > Cc: [email protected]; [EMAIL PROTECTED] > > Sent: 4/20/02 7:09 PM > > Subject: RE: [COUPERS-TECH] [COUPERS] 87 Octane Gas > > > > ----[Please read http://ercoupers.com/disclaimer.htm before following > > any advice in this forum.]---- > > > > Hi Ken, > > Just a guess, but I'd say that the grounding wire going from your > > mag switch to the mags is probably > > grounding out at the back of ths switch. Since it effects both mags in > > order to kill the engine > > completely I'd say either the swithch itself or right at the top end of > > the wires where they connect. > > Could be that the wire has a little slack there and by raising the nose > > it makes a bare wire(s) touch > > some metal and thereby grounds out the mags as if the switch had been > > turned off. > > Like I said, just a guess, but one more thing to check before you > > fly it again. It surely wouldn't > > hurt to check both wires all the way to their respective mags to look > > for a bad spot in the insulation. > > Especially where it goes through a clamp or the firewall. Or if it is > > 'rubbing' against any metal such > > as the engine mount for example. > > > > Bob Saville > > > > [EMAIL PROTECTED] wrote: > > > > > ----[Please read http://ercoupers.com/disclaimer.htm before following > > any advice in this forum.]---- > > > > > > I'll add my experience(s) to the list on the subject of engine > > stoppage. > > > > > > I have an Alon. I've put about 350-400 hours on it without similar > > engine > > > incident. I did replace two pistons about 6 months ago. (I had real > > low > > > compression on one cylinder and low on the other one.) It already has > > new > > > slick mags (2 years ago). I only use 100LL. > > > > > > Last Nov my engine quit at about 300 feet. Fortunately there was a > > nice > > > field ahead of me so I landed uneventfully. It was a perfect carb ice > > day > > > and I still suspect that was the problem. I flew the plane out of the > > field > > > later in the day. > > > > > > I flew the plane several times after that without incident. But a > > month > > > ago, after flying around for about an hour I stopped at a local > > airport for > > > fuel and breakfast. As I rotated on take-off the engine quit. I set > > the > > > nose back down and the engine ran fine. I taxied back and it happened > > > again. I did this three times with the same results. The engine > > didn't > > > sputter, it just quit--like the key had been turned off. The run ups > > and > > > static run-ups checked ok and taking off with carb heat on didn't > > help. I > > > should have tried lowering the tail while tied down and running but I > > > didn't--too frustrated at the time. > > > > > > My Mechanic and I discussed all the possible problems and talked to > > several > > > other people, including other Alon and Ercoupe owners. The comments > > were > > > usually: (a) Alons just do that, keep current on emergency landings > > (b) > > > Alons do that because the gasolator sits too low on the firewall; > > (c)the > > > fuel line must have a hump in it causing a vapor lock; (d)the carb is > > > contaminated; (e)it has nothing to do with the fuel, fuel line, carb > > or > > > vapor locks--something is shorting-out both magnetos---maybe a bad > > ignition > > > switch. > > > > > > So we checked the carb and it was clean and looked good. > > > > > > I re-routed the fuel line because there was just a slight hump in it. > > The > > > fuel line had been replaced about 2 years ago just because the old one > > was > > > ratty on one end. The slight hump had been there for the past 100 > > hours + > > > of flying. > > > > > > I checked the vent hole in the fuel line caps--all ok. > > > > > > I replaced the ignition switch although I can't imagine how the switch > > would > > > go bad such that raising the nose would cause it to short out. > > > > > > But I didn't find anything else unusual and there was no definitive > > cause > > > found for the engine quitting. After all of this, the plane flew just > > fine. > > > I flew it above the airport for a while before heading home. That was > > last > > > week and the weather has been bad ever since so I haven't gotten to do > > > enough test flights to know if the problem is solved. > > > > > > I don't think my experiences really add anything accept more > > confusion. > > > Most probably our experiences are not caused by the same thing. > > > > > > Ken Doyle > > > Alon N5477E > > > Springfield, Mo > > > > > > > > ==^================================================================ This email was sent to: [EMAIL PROTECTED] EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Sid.bAhN69 Or send an email to: [EMAIL PROTECTED] T O P I C A -- Register now to manage your mail! http://www.topica.com/partner/tag02/register ==^================================================================
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