Prime to start

Joe_B1

Joe_B1

Line Up and Wait
Gone West
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Joe_B
I have an archer with an O-360-A4M that requires no less than 4 shots of primer to start regardless of if it is cold or warm. Every warrior I have ever flown did not require any primer when it was warm so I am wondering if this is normal for the bigger engine.
 
The Archer I fly is the same way. I also assume it’s normal.
 
Mine too - and I cleaned the primer nozzles last annual, still 4 pumps on my O360.
 
5 prime here, the first one doesn’t count . It has always been that way. For a hot start I might be able to get away with 2-3 shots, not always
 
I can still hear my crusty old CFI's voice now..."Every start is a primed start, Bill"
 
Do you prime while cranking, or prime before cranking?

On the O-540, I never prime in the warmer months.
 
Who you? The Mooney is an IO, so I technically don't worry about a primer anymore.
 
EdFred said:
Do you prime while cranking, or prime before cranking?

On the O-540, I never prime in the warmer months.
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Prime x4 then crank, usually starts in 1-2 turns.
 
WannFly said:
5 prime here, the first one doesn’t count . It has always been that way. For a hot start I might be able to get away with 2-3 shots, not always
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Hot start I usually just pump the throttle once and crack it 1/4in and start. Works every time!
 
O-360-A4K. Five or six shots of prime, the last one delivered as the starter is engaged. Never fails. Before I learned the priming-while-cranking trick, the engine would not start, would flood and then I'd run the battery down.
 
RyanB said:
Hot start I usually just pump the throttle once and crack it 1/4in and start. Works every time!
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I have not had success pumping the throttle. If I do that, the engine will kick but not start. Guess mine is fuel hungry.
 
No primer on my plane, O-290-D. A couple of throttle pumps as it's cranking and it starts right up.
 
In the winter my Warrior (-161) needs 4-5 primer shots and a minute to volatilize to start easily. Hot starts, e.g., right after fueling, require no prime.
 
Primers get worn and corroded, and if the tiny check balls in them aren't seating they don't pump well and you'll have to pump more. Their O-rings wear and it will suck in air and air doesn't prime an engine well at all. The primer nozzles get gummed up with dried and cooked-in gasoline, and will dribble instead of spray, and you'll need more pumps to get useable vapor.

If the carb float is set too low it won't deliver fuel easily at cranking speeds.
 
4 pumps of the primer and like someone above said, the first one doesn't count. Never tried cranking and priming at the same time.

Primer re-build kits are cheap and easy to install. I didn't know what a worn out primer felt like until I rebuilt mine.
 
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Joe_B1 said:
I have an archer with an O-360-A4M that requires no less than 4 shots of primer to start regardless of if it is cold or warm. Every warrior I have ever flown did not require any primer when it was warm so I am wondering if this is normal for the bigger engine.
Click to expand...
Out of curiosity, how many blades before it fires? If you give only 3 shots of primer, how many blades before you give up and stop cranking?
 
cherokee 180 with same 0-360. I experimented with different number of shots hot/cold for many flights. Final conclusion; at all times, 4 shots works. Still no idea why hot start needs priming, but have stopped worrying/thinking about it; get in, 4 shots, engine starts in 1/2 turns.
 
asicer said:
Out of curiosity, how many blades before it fires? If you give only 3 shots of primer, how many blades before you give up and stop cranking?
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Usually 3 or 4 blades but 3 primer shots won't do it, 4 will almost always get it going. If it doesn't start in 2 turns, I prime 2 more shots.
 
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