now the primer pump gave up :=\

[bavareze]

new day, new problem:

 

tried to start the engine (1963 Model C, O360-A1D) - nothing, not even some pops.  The throttle felt a little weird: when I was pushing it back and forth to prime the engine, it was less resistance.  It didn't fell like i was pushing fuel.  My plane does not have a separate primer, it is supposed to be primed with by pumping the throttle.

 

Since I was already suspecting the primer, I squirted some fuel in the intake and the engine started right up with no issues.

 

What's the best way to tackle this issue?  Does the carburetor need to come out and send it somewhere to be fixed, or this is something that could be fixed with the carbuertor installed?

 

Thanks!

[N201MKTurbo]

Depends how good you are with carbs. It sounds like the check valve in the bottom of the accelerator pump is stuck. Honestly, your best bet is to send it out for overhaul.

[ShuRugal]

The -A1D on our C models does not have a primer pump. It does have an accelerator pump inside the carburetor, however, and that is what 'primes' the engine when you tickle it with the throttle.

That said, our carbureted engines are usually pretty good about starting up, as long as there is fuel in the carburetor bowl, unless it's very cold outside.

What I suspect may be the case for you is that you had a car of vapor lock in the line between the fuel tanks and carb bowl. The electric boost pump is a rotary vane pump and incapable of self priming. If you get air in the line leading to it, it won't fill the carb bowl in prestart.

When the happens, the carburetor won't get any fuel until the engine has been turned over enough times for the mechanical pump (which is capable of self priming). This can feel like a VERY long time if you're used to the engine firing on 1-3 blades.

Did you happen to notice if you had fuel pressure after running the boost pump, prior to attempting to start?

To test your accelerator pump (before you go ripping things off)

1: start the engine
2: warm it up to normal temperature
3: do your run up procedure
4: full rich mixture
5: advance the throttle briskly (1 second from closed to open, smooth motion). The engine should accelerate without any hesitation or coughing. If it does, the accelerator pump is fine, and your starting issue was most likely related to air in the line.

Sent from my Pixel 5a using Tapatalk

[PT20J]

Keep in mind that the primary purpose of the accelerator pump is to supply extra fuel required by the engine to accelerate rapidly. The main jet won't supply enough fuel until the airflow increases through the venturi. So, in the case of a go around, you could find the engine balking if the accelerator pump is kaput. It's really a safety issue and I would have the carb overhauled.

[bavareze]

the fuel pressure was increasing when I tested the electric fuel pump prior to starting the engine.

 

there was plenty of fuel in the carburetor bowl.  I checked that by removing the bottom drain plug.

 

the throttle lever feels like I'm not pumping anything when pushing/pulling it and I feel no fuel smell.  It feels different than before, and this makes me believe it is not squirting.

however: upon starting the engine, the engine has accelerates properly when pushing briskly the throttle - and this seems to indicate the pump is actually working.

 

before starting to remove things and send the carburetor for overhaul, is there anything else I could do to confirm the problem or help it work?

 

My guess it's that I have a sticking fuel valve at the pump, caused by not flying it for 6 months.  Once that is unstuck, it should be good for another 60 years.  But I might be wrong.

[PT20J]

You could pump the throttle 20 or so times and go out and see if you smell gas at the air filter and/or it drips out the drain.