Priming and throttle position

[Stan Cooper]

Interestingly, the C162 does not have a primer. Instead, the POH says to pump the throttle. I will continue to use the primer in my 172.

That's the same as with my O-200 powered Zodiac SLSA; there is no primer. During my insurance required transition training I asked the CFI (who had 500 hour instructing in Zodiacs) where the primer was located. He said there wasn't one; "open and close the throttle a couple of times and it'll start right up." That's the procedure I've used since I bought the plane four years ago without any problem.

 

[Tom-D]

That's the same as with my O-200 powered Zodiac SLSA; there is no primer. During my insurance required transition training I asked the CFI (who had 500 hour instructing in Zodiacs) where the primer was located. He said there wasn't one; "open and close the throttle a couple of times and it'll start right up." That's the procedure I've used since I bought the plane four years ago without any problem.

We know fuel is produced when you stroke the throttle, so when you are cranking the fuel is sucked into the induction system immediately, no waiting for drip down. And wait for the accelerator pump to squirt, prior to closing the throttle.
and remember you never prime any engine that isn't cranking. that is how you get induction fires

 

[AKBill]

$39 apiece sound high. Do you have the AN4022-2, the 90° version?

Lycoming O-320-E3D, pn 63D21408 is what my parts book shows.

 

[Huckster79]

Isn't the risk of an induction fire increased quite a bit by using this technique?

Yup! Happened in my training days to me! Got it out but puckered my behind for a minute!

 

[Stan Cooper]

We know fuel is produced when you stroke the throttle, so when you are cranking the fuel is sucked into the induction system immediately, no waiting for drip down. And wait for the accelerator pump to squirt, prior to closing the throttle.
and remember you never prime any engine that isn't cranking. that is how you get induction fires

Ah hah! Thanks, Tom.

 

[Dan Thomas]

Lycoming O-320-E3D, pn 63D21408 is what my parts book shows.

Same thing, with a Lycoming price.
http://www.aircraftspecialties.aero/nipple-assy-primer-63d21408/

https://www.aircraftspruce.com/catalog/hapages/primperfittingsan4022-1.php

This sort of thing helps to keep owners poor.

 

[woxof]

Thanks for the responses guys. I'm not sure I ever figured out if it is somehow better for the throttle to be at idle for the start because it is using the idle circuit versus being cracked open where perhaps the idle circuit is not being used.

Any thoughts?

 

[Dana]

Just more internet jargon. Lycoming cautions against using the throttle for priming. Pumping the throttle in place of using the primer doesn’t affect the cylinder mixture in any significant way. Even so, the accelerator pump should only be used when the starter is engaged.

From the Lycoming O-235 / O-290 operator's manual:

g. Set throttle at 1/4 travel.
h. Move mixture control to "Full Rich".
i. Turn boost pump on.
j. Pump throttle to full open and back to idle position for 2 to 3 strokes
for a cold engine. If engine is equipped with a priming system, cold
engine may be primed with 1 to 3 strokes of the priming pump.
k. Set magneto selector switch. Consult airframe manufacturer's
handbook for correct position.
1. Engage starter.
m. When engine fires, place magneto switch in "Both" position.

No primer on my plane (O-290-D).

 

[Tom-D]

From the Lycoming O-235 / O-290 operator's manual:


No primer on my plane (O-290-D).

Remember Lycoming priming system is different than Continentals
it may make a second or too more for the gas to drop out if you are not cranking.

 

[Tom-D]

From the Lycoming O-235 / O-290 operator's manual.

If the engine is cranking when the throttle is stroked, it most likely will start