Hamish Posted December 24, 2017 Share Posted December 24, 2017 Unable to find any answer resulting in this post. Have recently converted a Saito 45,4# and ASP 61, 4# to petrol with Pegasus CDi ignition I am impressed by how easily the engines start and run but at the moment only test bench. The Satio is in an old cub ready for a test flight, weather permitting. I notice that the petrol remaining in the fuel tank is very discoloured due to the exhaust pressure feed. Obviously the engines run on this fuel but on completion of running I have contained this fuel in a separate container and not recycled. Can I ask how you petrolheads deal with this? Not considering a separate pump even if available. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted December 24, 2017 Share Posted December 24, 2017 You shouldn't be using exhaust pressure to the tank with petrol ! You are running a serious risk of fire as petrol exhaust is much hotter and pipe from exhaust can be damaged by heat and break down then the fire risk starts! Use a pump as all modern petrol engines do or just use normal carb suction to draw the fuel. Quote Link to comment Share on other sites More sharing options...
Hamish Posted December 24, 2017 Author Share Posted December 24, 2017 I thank you for the advice and suggestion. From JE "Plumbing the exhaust into the tank has been a question for many years from way back in the early 70's but I have never heard of an incident wherein a fuel tank exploded. Webra sell a 150 spark engine and it is supplied with muffler pressure so it is not a concern to them. The hot gas would not be a problem but carbon might be however, I would consider the chances in the million to one odds maybe even better. Besides, methanol is not too slow igniting with a hot glow look at glow plugs and we have been pumping hot gas into methanol for a long time. I would be prepared to say not a problem." Its how I recycle fuel or just run dry? Quote Link to comment Share on other sites More sharing options...
Ultymate Posted December 24, 2017 Share Posted December 24, 2017 The only way I can see you not using exhaust pressure is to go to an electric pump like this Pump. I am of course assuming you've tried running your engine without pressure. The above pumps do work as a friend of mine has one on a inline 4 cylinder OS that he converted to petrol. Sadly the carbs fitted to glow engines are little more than dripping taps Quote Link to comment Share on other sites More sharing options...
Hamish Posted December 24, 2017 Author Share Posted December 24, 2017 Gave the ASP a run without pressure feed and it appears to be running ok so thanks for that suggestion. Have yet to tweak this engine so further experimenting worth it. I will more than likely take the million to one chance rather than an extra £35+ for a pump on an experimental project. Will drain tank into a separate container and reuse on next fill up rather than contaminate good fuel. Thanks all for advice. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted December 24, 2017 Share Posted December 24, 2017 If you are using a felt clunk, as is generally advised for petrol, you might be best leaving some petrol in the tank to stop the filter drying out and crumbling. Quote Link to comment Share on other sites More sharing options...
Hamish Posted December 24, 2017 Author Share Posted December 24, 2017 Thanks Bob, it is a felt clunk so will take your advice which really answers the whole question of how to recycle fuel. Quote Link to comment Share on other sites More sharing options...
Rich too Posted December 26, 2017 Share Posted December 26, 2017 I agree, but felt clunk or not, you shouldn’t drain the fuel. Any rubber parts in the system will dry out.. Quote Link to comment Share on other sites More sharing options...
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