Primer issues

aftCG

Well-known member
Location
Tacoma, WA
#1
Anyone here every have a primer stop working with little notice?
Looking back I probably had a warning I ignored. My plane has typically always started cold with three pumps.
The past few months it has taken four but I wrote it off to cold weather.
Last week I went up to abuse the pattern and had a hell of a time getting it started. I added a fifth and sixth pump and then concluded that I must have flooded it.
I got out and looked for gas running out of the cowl (none), let it rest and then went through a flooded engine procedure. Not a cough.
More primer (a lot more) and it eventually it stumbled to life. Ran perfectly after that.
Well the same thing happened two days ago. I went through the same logic of suspecting it was flooded. It wasn't.
Real sure my primer isn't priming now. Is that common?
One thing my IA pointed out was that the Citabria has the primer line come off the fuel shut off valve up stream of the actual shut off which means I might have to drain the fuel system before opening the primer mechanism.
Any thoughts appreciated.
 

Bob Turner

Well-known member
#2
What kind of carb? What temperatures are you starting in?

I have all Strombergs, and they start cold down to about 55 degrees F by pulling seven blades with the throttle completely closed.

If you have a starter, the M-S carb can be used as a primer - while cranking, sharply go between idle and full throttle three times. Don't do that unless you are cranking; you do not want fuel dribbling on the ground.
 

aftCG

Well-known member
Location
Tacoma, WA
#3
Bob,
I have a Marv Schebbler (or however that's spelled) and one of those new fangled starter things you mention.
I'm not talking Minnesota cold. 50-65 degrees.

Great tip on the throttle. I wasn't sure if it had an accelerator pump, and the other engine I fly (R985) says to NEVER pump the throttle.
 

Bob Turner

Well-known member
#4
The problem is when you pump while not cranking. The Marvel Schebler does have a pump, but at 60 degrees you really shouldn't need prime. With the butterfly completely closed you should hear fuel being sucked in there when pulling the prop through.

We start the Stearman that way - get it cranking, three sharp jabs all the way from idle to full, and off we go. If it floods, crank wide open and it goes on the third blade.

I don't know how to fix primers. Mine is a Lunkenheimer, and has a leather plunger. Been on the shelf since 1969.