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mikey70

Hard Staring ULS-Starting Carbs

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I can't imagine this hasn't been covered but I could not find it in a search. I have had a 2007 CTSW since October of last year. Always started immediately cold with throttle closed and choke (starting carbs) on. Hot starts immediate with throttle cracked. Did the annual in May, replaced floats per the SB, increased idle from 1700 to 2000 rpm, and synched carbs. Starts were normal and it idled and ran much smoother after the carb synch. After the annual I did a 10- hour cross country and when I came home I decided to close the fuel valve and run it out of fuel since I was going to be gone for a few weeks.  Upon return it would not start, plugs were dry,  so I removed the carb bowls to check the needle and seat, everything looked normal but still did not want to start easily but eventually caught. Once started it idles and runs completely normal. I decided to reverse my changes so I put the idle back to 1700 and re synched the carbs since I had manipulated the carbs on and off numerous times. Engine now running even smoother than before, literally zero vibration at any RPM, but still hard to start. Using a normal starting procedure I crank it for 5 seconds then rest then crank again. I may take 3 tries or as many as 7. Fuel pressure is 3.5 running 2.5 cranking. Once running the starting carb will make it run faster and rougher which seems correct, Bowden cable adjustments are correct on the starting carbs. The only thing that makes any sense is that the starting carb jets plugged when I ran the bowl dry, if so, then why do they appear to work correctly once the engine is running?  I have been running nothing but 91 octane ethanol free unleaded. On the cross country in question I had to buy some 100LL so probably had 50/50 mix. I would change back to the original floats but they worked fine on the cross country, only had problems after running the carbs out of fuel. I will clean the starting jets but any other thoughts would be appreciated. 

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How old is the battery?  Maybe you are cranking at a slower RPM then you used to but its not obvious to your ear.

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Obviously not relate to your current problem, but I have never heard of anyone closing the fuel valve and letting the engine run to dry out the bowls before storage.

What is important is shutting the fuel valve after shutdown. When I forget to do this, my subsequent starts are difficult. I think this may be a result of some fuel leaking across the float valves over time (like overnight) and dribbling into the carb throats.

Mike Koerner

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The battery was replaced at the annual, there was nothing wrong it was just two years old and I didn't want to be stranded. I think mine was changed to a PC 510 years ago so I stayed with it. If they are fully charged they are just large enough to get the job done except if you try to run everything including a Halogen Landing light. Then you will eventually get low voltage alarm. I keep mine on a battery tender when not in use. 

I thought I was doing myself a favor by draining the carb bowls but I don't think I will do it again. For really long term storage (like 3 months or more), I would either drain the tanks and carbs or replace all the fuel with 100LL, it will last a long time before getting funky. I noticed on my fuel valve I cannot completely shut it off unless I have the key out. I noticed it when I serviced the gascolator and it kept on dribbling. 

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30 minutes ago, mikey70 said:

I noticed on my fuel valve I cannot completely shut it off unless I have the key out.

The design intent is to keep you from flying without opening the valve. You are not supposed to be able to close the valve with key still in.

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5 hours ago, Ed Cesnalis said:

The design intent is to keep you from flying without opening the valve. You are not supposed to be able to close the valve with key still in.

As a matter of semantics . .

Another way of looking at that . . . the ignition key cannot be inserted . . until the fuel valve lever is raised and out of the way.

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15 hours ago, WmInce said:

As a matter of semantics . .

Another way of looking at that . . . the ignition key cannot be inserted . . until the fuel valve lever is raised and out of the way.

Unless you have. CTLSi.  In that plane the ignition key and the fuel lever are separate.

 

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3 hours ago, Duane Jefts said:

Unless you have. CTLSi.  In that plane the ignition key and the fuel lever are separate.

 

But with the CTLSi there is no danger of starting the engine with the fuel off, because it will not start. A CT with the ULS can start and run for a while because of the fuel in the float bowl. I doubt you could get in the air before the fuel in the bowl ran out, but I suppose it is possible. I have seen aborted take offs before in a Piper, because the student switched tanks, but accidently selected the off position. They were at rotate speed when it quit.

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10 hours ago, Duane Jefts said:

Unless you have. CTLSi.  In that plane the ignition key and the fuel lever are separate.

Thank you, Duane.

I did not know that (and a whole bunch of other stuff too).😁

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Incorrect.

The CTLSi , at least those produced in Europe ( are they produced any differently for other markets ?) , have the same (cannot insert/start) ignition, without the fuel lever being moved to the UP position

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On 7/12/2019 at 7:20 AM, Roger said:

Incorrect.

The CTLSi , at least those produced in Europe ( are they produced any differently for other markets ?) , have the same (cannot insert/start) ignition, without the fuel lever being moved to the UP position

N79202’s fuel lever does not interfere with ignition key and vice versa. Perhaps all fuel injected planes are not like this one, but for this one it is correct.

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Strange, I thought all CT planes were the same on this. I appreciate this feature on my CTLS since i managed to get through startup, tower call, taxi and run up in an Evektor before I noticed the fuel valve was shut off. I missed the checklist item for fuel valve, but later caught the fuel pressure check item during run up. The ULS was perfectly happy all through it and might have gotten me through my take off roll before .... you know.

Along those same lines, I have my ignition key on the parachute ring so I can't start without activating the 'chute.

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3 minutes ago, SportFlyer1 said:

Along those same lines, I have my ignition key on the parachute ring so I can't start without activating the 'chute.

Doesn't this lead to parking your airplane with the ignition key in the plane?  Are you relying on the door lock for theft protection?

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Yes it can be an issue. I know it irritates Roger, who needs the key (but not the chute) to work on it. So when leaving it in a strange place, I can slip the key off the ring and onto the baggage door key ring. To be honest this hasn't come up yet, since all my trips of late have been local. For me the bottom line is that when I finally reach for the chute handle, it really will pull.  😃

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I pulled the bowls off again and checked the starting carb jets, clean but I cleaned them anyway, cleaned and inspected the cavity they rest in, blew through the Starting Carb induction tube to make sure it was clear, removed the starting carb and checked it all over and replaced the carb bowl gaskets. Everything looked normal and was clean, there was fuel in the bowl when I took it off. All normal but it still take way too long to start, I don't think the starting carb is working. 

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So today I turned on the fuel valve and did some other work for about an hour before coming back to pull the airplane out. I also tried a different method of starting. Half choke instead of full and throttle cracked about 1/4 inch instead of closed. Just like magic it started INSTANTLY  just like it used to. I used to leave the fuel valve on all the time and just recently started turning it off. I understand some of you have problems leaving it on but that does not seem to be the case for me. If the floats, needle and seat are working correctly it should not be a problem. After all, we fly for hours with 3.5 psi from the fuel pump. Static pressure would be .43 psi per foot so maybe .75 to 1.0 psi  at the carb since the tank is a couple of feet above the carb. (thats for water, slightly different for fuel.) For now I'm just happy to confirm there is nothing wrong with the equipment while I try to isolate whether its the fuel valve being on or starting procedure. 

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