Starting a cold motor

[crewchief]

Had my 6139s Thermoquad rebuilt by National Carburetors, they did a great job. Fresh rebuilt engine and I have to pour some fuel down the carb when it’s cold (carb has fuel and does spray as it should) every time before it starts cold. The fuel is fresh, no leak back or evaporation going on, good pump pressure and I’m using 91 non-ethanol fuel. It starts right up when warm without any problems what so ever and runs great.

When I don’t add some fuel down the carb first and get in; I have to pump it 10 – 12 times, before it will start. I never had to pump it that much before, maybe two or three times at most. Again it sprays at every pump of the throttle. The electronic ignition system is fine, no vacuum leaks or timing issues.

Just can't figure this one out; am I missing something here?

 

[discharger1332]

missing choke? or choke is not functioning proper. I had a old carb once that would shut the flapper when i pumped the gas so it would cut off the air, i would have to open the hood and open the flapper and it would fire right up.

 

[TrailBeast]

Yep, missing or mis adjusted choke.
Do a google search for adjusting a choke on a Thermoquad.

Here, I did it for you.
The Lost Art of Choke Adjustment | Hemmings Motor News

 

[crewchief]

Yep, missing or mis adjusted choke.
Do a google search for adjusting a choke on a Thermoquad.

Here, I did it for you.
The Lost Art of Choke Adjustment | Hemmings Motor News

Thanks for the research. My choke does close like it should and when put to the floor, it opens slightly as required. Even if I leave the choke open slightly, it still requires a lot of pumping of the pedal.

 

[TrailBeast]

Thanks for the research. My choke does close like it should and when put to the floor, it opens slightly as required. Even if I leave the choke open slightly, it still requires a lot of pumping of the pedal.

I hear ya, but it's obviously not choking it enough on startup.
I go through the same thing here believe it or not.
Tightening up on the choke a little in the late fall and backing it off a little in spring is a yearly routine.
One or two pumps to the floor and turn the key to start, and then one more light tap to bring the idle down to the normal high idle, then one more tap after it warms up a bit to get it to idle all the way down.
This is how it should work, but nothing is perfect usually, so as close as you can.

 

[Bulldozer]

I had one that did that. I would have to prime it first. It finally caught on fire and burned my engine bay. it backfired after it died one day. the gas is draining back into the system and the fuel is evaporating out of the carb. I do not like thermobogs.

 

[340demon]

Check the setting on the acc pump they may have it asset on the low side

 

[crewchief]

Check the setting on the acc pump they may have it asset on the low side

Ok, what do I look for? Not sure how to adjust the carb for the perfect start up.