Carb seems to be draining down.

[Rapid Roy]

74 C10 350/TH350 4 bbl Carter Quadrajet. When stopped for maybe 5-10 min., restarts fine. After around 20 min. or more, does not want to kick right off and have to press accelerator more to get to start, not a problem when sits all day or over night. Then runs slightly rough for a few minutes till it settles out then it's ok. If carb is draining down, where is it draining? I thought fuel was draining back to pump, or maybe draining from fuel bowl into intake and where it is draining from?


TIA

[VileZambonie]

Carter Quadrajet?

[bd]

Carter manufactured Quadrajet carburetors under license with Rochester whenever Rochester was unable to fill the demand.  IIRC the only deviation from Rochester Quadrajets was "Carter" cast into the float bowl instead of "Rochester."  It raised more than a few eyebrows in the service department when they first appeared.  That became little more than a notation in someone's history book once Carter shut down in 1984/1985.

[Rapid Roy]

Yes....has Carter on side #7044202. From all info I have found, it is  Rochester with Carter name on it. Or something like that.

[VileZambonie]

Are you seeing any fuel fouling on the plugs? If in fact the bowl is draining down you can try sealing the well plugs.

[Rapid Roy]

Haven't started doing anything as I did not know where to start. Have not pulled any plugs yet. Not sure if bowl is draining or where it is draining from in carb. No fuel leaking on outside at all.

[blazer74]

If it starts fine the next day wouldn't be a drain down problem.
More like heat soak flood problem.
Pressure builds up and overcomes the needle/ seat causing fuel to run into the intake making it hard(er) to start.
Fuel pump can cause this.
What the condition of the carb?
Carter quads are virtually identical except for the name.

[Rapid Roy]

Got truck in July 2015. PO said carb had been rebuilt. First start in mornings, tap accelerator to engage chock, turns over several times then starts, runs ok. Sitting at work 9 hours, tap peddle, starts right up and does not turn over several times. As I mentioned, stop 5-10 min. starts right up. Stop for approx. 20 min. or more, does not want to start right up without pressing peddle for more gas then runs rough for a few minutes. May need rebuilt, not sure the reliability of the  rebuild.

PO also said brakes, master cylinder, hoses were replaced. I found master cylinder rear reservoir was contaminated. Had water in it. I had to redo all of it so this is why I cannot rely on rebuild reliability.

[blazer74]

I'd check fuel pressure while it's running and after shut down at your specified times and see how high it goes, anything over about 7  lbs is too much.
You can plumb in cheap in line press gauge.

[Monkey Uncle]

Got truck in July 2015. PO said carb had been rebuilt. First start in mornings, tap accelerator to engage chock, turns over several times then starts, runs ok. Sitting at work 9 hours, tap peddle, starts right up and does not turn over several times. As I mentioned, stop 5-10 min. starts right up. Stop for approx. 20 min. or more, does not want to start right up without pressing peddle for more gas then runs rough for a few minutes. May need rebuilt, not sure the reliability of the  rebuild.

PO also said brakes, master cylinder, hoses were replaced. I found master cylinder rear reservoir was contaminated. Had water in it. I had to redo all of it so this is why I cannot rely on rebuild reliability.

Mine behaves similarly, but my quadrajet is new, as is my fuel pump.  Haven't had the truck for long, so I just chalked it up to not having driven a car with a carburetor for 30 years.  I've never had it totally refuse to start; I just have to keep the ignition engaged for 5-10 seconds until it fires.  5-10 seconds doesn't sound like much when you're reading this, but when you're sitting there holding the key, it seems like an eternity to someone who's used to fuel injection.  I'm thinking this is just normal carb behavior?