Issues adjusting carb

[barmanvarn]

I apologize for asking this as I know it's been asked on here a million times already. I did do some research and tried some things based on what I read, but I'm still having issues.

It seems the engine will only run with the choke in the 40-70% open range (approx). If I close the choke completely, the engine dies. If I open the choke all the way, the engine dies.

As I open from 40% to 70% the RPMs go up and seem to max around 60% open.

As suggested on other posts I've sprayed carb cleaner around the carb while running and didn't detect any vacuum leaks. I also started w/ the mix screw at 2 turns out and slowly backed it out a half turn at a time but nothing I did stopped the engine from dying as soon as the choke was opened all the way.

Thanks in advance for any assistance you can provide.

[Steeveedee]

Try capping the vacuum ports one at a time. There could be a vacuum leak at the other end of the line. Did you spray directly on the primary throttle shaft, both sides?

[barmanvarn]

Originally Posted by Steeveedee

Try capping the vacuum ports one at a time. There could be a vacuum leak at the other end of the line. Did you spray directly on the primary throttle shaft, both sides?

Bear with me as I know jack about carbs....

This is just a simple single barrel carb. There are no vaccuum ports that I'm aware of.

I literally sprayed every spot on the carb...one spot at a time, listening for RPM changes.

I didn't think to check the fuel line where it comes out of the pump. Is that what you are suggesting?


Sorry if I misunderstood you.

[Mike C]

Carter or Rochester? I have found the YF Carter to be THE most persnickety carburetor I have ever worked on. Either way, most likely you have a small internal passage blockage that makes it want to run lean and a complete soak/flush of the carb will return it to function. The smaller the carb the more easily they get junk in them and cause running issues.

[barmanvarn]

Originally Posted by Mike C

Carter or Rochester? I have found the YF Carter to be THE most persnickety carburetor I have ever worked on. Either way, most likely you have a small internal passage blockage that makes it want to run lean and a complete soak/flush of the carb will return it to function. The smaller the carb the more easily they get junk in them and cause running issues.

I think Rochester? I seem to recall seeing that stamped on the side but will confirm. I did rebuild it about 10 years ago when I first got it running but then it sat for 10 years as life got in the way. I suppose I should order another rebuild kit and give it a clean and rebuild to either fix the issue or at least rule that out as the issue?

[body bolt]

Remove the idle mixture adjustment screw and blast carburetor cleaner in there trying to get to the hole at the end. Replace the screw and try again.

[barmanvarn]

Originally Posted by body bolt

Remove the idle mixture adjustment screw and blast carburetor cleaner in there trying to get to the hole at the end. Replace the screw and try again.

Great idea! thanks.

I'll give that a shot and get back to you. I'm working right now so may be later today or tomorrow before I can try that.

thanks again

[geezer#99]

Could be intake gasket leaking.
A pic of your motor helps.

[body bolt]

But look for vacuum leaks first. I take a garden hose or a bottle of water and pour it around the carburetor, its base, on the hoses, etc. and listen a change in running. The water will (very) temporarily block a leak and you'll hear the difference.

Originally Posted by barmanvarn

Great idea! thanks.

I'll give that a shot and get back to you. I'm working right now so may be later today or tomorrow before I can try that.

thanks again

[barmanvarn]

Originally Posted by body bolt

But look for vacuum leaks first. I take a garden hose or a bottle of water and pour it around the carburetor, its base, on the hoses, etc. and listen a change in running. The water will (very) temporarily block a leak and you'll hear the difference.

I mentioned earlier that I had tried that approach with carb cleaner. Would doing the test againt but with water produce a different result? thanks

[barmanvarn]

Originally Posted by geezer#99

Could be intake gasket leaking.
A pic of your motor helps.

Just so happens I took a pic yesterday. Excuse the mess. This vehicle doesn't even move and was a mess when my dad handed it off to me. I'm just goofing around right now to see if I can get the engine running smoothly.

[body bolt]

If you're convinced there are no leaks then no.

Originally Posted by barmanvarn

I mentioned earlier that I had tried that approach with carb cleaner. Would doing the test againt but with water produce a different result? thanks

[Davidf]

Trash is the carb. It needs to be opened up and cleaned.

Try this first: Get the engine running at a fast idle any way you can. Then put your hand over the air horn. This will create a strong vacuum in the air ports of the carb and hopefully clear any debris.

[barmanvarn]

Originally Posted by body bolt

If you're convinced there are no leaks then no.

I'm old enough and inexperienced enough to know better than to say that I'm sure about anything. LOL

I just wasn't sure if testing with water could possible yield different results as this is all new to me.

Thanks again!

[barmanvarn]

Originally Posted by Davidf

Trash is the carb. It needs to be opened up and cleaned.

Try this first: Get the engine running at a fast idle any way you can. Then put your hand over the air horn. This will create a strong vacuum in the air ports of the carb and hopefully clear any debris.

Will add that to things to try as soon as I get the chance.

thanks!

[Steeveedee]

Originally Posted by Davidf

Trash is the carb. It needs to be opened up and cleaned.

Try this first: Get the engine running at a fast idle any way you can. Then put your hand over the air horn. This will create a strong vacuum in the air ports of the carb and hopefully clear any debris.

We used to call that a "six second tune-up". Rev it up, choke it to pull a bunch of fuel through and hopefully clear any guck lurking in the bowl out.

[barmanvarn]

Originally Posted by Steeveedee

We used to call that a "six second tune-up". Rev it up, choke it to pull a bunch of fuel through and hopefully clear any guck lurking in the bowl out.

I like it! Will certainly give it a shot.

[Steeveedee]

If you do this, keep the throttle open far enough not to kill it. No need to race it at high RPM, just keep it going, and run at a speed enough above idle to clear the carbon off the plugs after you take your hand away from the air horn. There's gonna be black smoke everywhere. We didn't do this in front of the customers, they tended to freak out over all the smoke.

[barmanvarn]

Wanted to thanks everyone again for the advice. I had time to work on it yesterday and though I didn’t fully resolve the issue I did get it to where I can almost fully open the choke. I have a rebuild kit on the way.

Will work on it some more after I replace the water pump tomorrow as it making a squeaking noise.

[jumpsoffrock]

quite frankly I had a similar issue on a single barrel Holley on my Ford, I discovered I simply didn't have the idle set high enough.