Rogerck Posted May 6, 2014 Report Share Posted May 6, 2014 Our CTSW wouldn't start after sitting idle for a couple of weeks. Battery power and engine turnover were fine, but not even a sputter. Checked gravity fuel flow on carb side of fuel pump and flow was fine. The problem was finally resolved by draining fuel from the float bowls and fuel hoses at the gascolator, and draining several gallons of fuel from tanks at gascolator. After this process, and with fresh fuel added to the tanks, engine started right up. I've had this same situation once before with same "fix". It seems that fuel gets funcky when sitting in lines/float bowls for extended time and replacing fuel with fresh solves the problem. Not sure this really makes sense, but have no other explanation. Any ideas? Roger Kuhn Link to comment Share on other sites More sharing options...
FlyingMonkey Posted May 6, 2014 Report Share Posted May 6, 2014 Dumb question, but did you use the choke when trying to start? Engine turning on start without catching is exactly what mine does if I forget the choke on first flight of the day. Link to comment Share on other sites More sharing options...
Anticept Posted May 6, 2014 Report Share Posted May 6, 2014 Age of fuel? Was it sitting outside? Link to comment Share on other sites More sharing options...
Rogerck Posted May 7, 2014 Author Report Share Posted May 7, 2014 I used choke to start as normally done and fuel in float bowls was about 1 month old and never stored outside. Link to comment Share on other sites More sharing options...
Rogerck Posted August 1, 2014 Author Report Share Posted August 1, 2014 I had another hard engine start today after only one week form flying the CTSW before. Some facts: - The engine turned over like a champ. No battery problem here. - Engine ran fine during last flight and run up. No roughness or issues whatsoever. Engine and starting has been fine until today. - Fuel is always fresh - Other than components required for rubber change, nothing has been done to carbs. There are no fuel stains or wet spots on carbs. TT 650 hours. - No smell of fuel which might indicate flooding. - Disconnected fuel line between fuel pump and carbs. Flow was positive from gravity feed. When trying to start today, used normal procedure, throttle all back, some choke. Turned it over several times, not even a sputter. Tried turning again after 5 minutes, finally caught - at half throttle position. Once started, no roughness or issues with engine. Mag run ups were normal. Any ideas? Roger Kuhn Link to comment Share on other sites More sharing options...
FastEddieB Posted August 1, 2014 Report Share Posted August 1, 2014 Seems to be an epidemic! Link to comment Share on other sites More sharing options...
Doug G. Posted August 1, 2014 Report Share Posted August 1, 2014 Fuel pressure good? Link to comment Share on other sites More sharing options...
Roger Lee Posted August 2, 2014 Report Share Posted August 2, 2014 The starting circuits in some of these modules are failing and some are intermittent and will eventual quit altogether. These seem to come from the 2006-2007 modules although it could happen to any of them. For the most part modules have been fairly bullet proof, but there is a disturbing trend in the 2006-2007 modules which seems to manifest around 600-900 hrs. There is only one place I know of that can test modules in the US and that is Lockwood. It takes a fairly expensive machine to do the test. Dropping the temp with a large ice pack for 20-30 minutes has been a test that seems to work most of the time, but hasn't caught all of them. p.s. The engine can start with almost zero fuel pressure with the fuel in the carb bowls it just wouldn't stay running if there was zero fuel pressure and our fuel pump almost never goes to zero. On a high wing you could take the fuel pump off and it will still run just fine. I have posted those test results here on the forum. Link to comment Share on other sites More sharing options...
Rogerck Posted August 2, 2014 Author Report Share Posted August 2, 2014 Roger, What do the starting modules do differently during the start up phase that isn't being done during continued running (firing plugs)? It also seems strange that both units would not function. Today's hard starting was with a cool engine, maybe 78 degrees OAT. Not sure what you are suggesting with an ice pack. Lay it on the modules for 1/2 hour before starting? Roger Kuhn Link to comment Share on other sites More sharing options...
Roger Lee Posted August 2, 2014 Report Share Posted August 2, 2014 When you turn the key it is supposed to initiate the starting circuit which sets the firing timing at 4 degrees BTDC. Then after a start then engine quickly changes to 26 degrees BTDC. The soft start modules change the start timing to 3 degrees ATDC and then after the start and a delay of about 6 seconds the timing goes to 26 degrees BTDC. When the module(s) go bad it is usually the starting circuit that fails. So the engine tries to start at 26 degrees BTDC and it won't start. This causes enough of a hindrance to starting that one module won't start it. Link to comment Share on other sites More sharing options...
Mike Koerner Posted August 2, 2014 Report Share Posted August 2, 2014 Make sure you shut off the fuel valve (above the ignition key) after each flight. If not, some fuel may leak past one of the float valves, fill the bowl and dripple into the carburetor throat resulting in a hard start next time out. Mike Koerner Link to comment Share on other sites More sharing options...
Runtoeat Posted August 2, 2014 Report Share Posted August 2, 2014 Mike K. might have a good thought on using the fuel shut off to see if the float needle(s) might be leaking and flooding the engine. It would be worth a try for Roger Kuhn. Roger Lee, don't mean to hijack Roger Kuhn's thread but same subject here. My 2006 seems to be giving me a slow turn on the 1st turn of prop when starting. After the 1st turn of the prop, the engine then cranks OK and starts OK. Could the one or both modules be going to 26 BTDC momentarily and then to 4 BTDC after the first couple of turns of the engine? Wondering if this might be an indication of start of module failure? Link to comment Share on other sites More sharing options...
Roger Lee Posted August 2, 2014 Report Share Posted August 2, 2014 If the needle valves are bad and can not stop or control the fuel it will flood the carb and come out of the vent tube while it is running. The same affect happens with a sinking float. Just replaced a sinking float on an RV12 with 63 hrs on it. Even with the venting issue it should start right up because excess fuel goes out the vent and not usually back into the carb throat for use. The idle jet controls the fuel into the carb throat along with any choke you have engaged.. Link to comment Share on other sites More sharing options...
Rogerck Posted August 2, 2014 Author Report Share Posted August 2, 2014 Roger, If one of the starting modules is bad, can the cable for each be disconnected one at a time and then try starting? From what you've said, a bad module may prevent a good one from functioning. Roger Kuhn Link to comment Share on other sites More sharing options...
Roger Lee Posted August 2, 2014 Report Share Posted August 2, 2014 You should not disconnect one module and try on only one, this may cause damage. One bad one can prevent a start and sometimes you can have two bad modules. You may have had a bad one for a while and now a second one that did manage to get things started has now failed. That would be hard to determine. Link to comment Share on other sites More sharing options...
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