Hey guys. I've been getting hesitation when i apply the gas after rebuilding this carb. I was worried because the fuel filter was old and i couldn't replace it so i didnt. Lots of metallic flakes and crap in there. What I did was clean the fuel intake screw-on filter on the carb, then added a second inline filter about a foot from the carb. This made it work notably better but I was still getting some occasional hesitation.

Next I decided to take the carb apart halfway to clean what crap I could get at i had limited time because i had to drive somewhere. I didn't take apart the bottom pump diaphram assembly thing with the springs and what not and the throttle body, just cleaned the seat and needle and used a hollow pen to blow some crap out of the passages.
Now I have all the time in the world to fix because when i put the thing back on it's hesitating much worse to the point where i don't think i want to even drive it anywhere. I also hear hissing at idle and a louder hissing during the initial hesitation of the throttle. I can tell its coming from inside the carb because the hissing sounds hollow. Is that just the engine vacuum at it's normal work? Is it possible i tightened the gaskets too much? Because I checked double checked and triple checked every screw for a firm tightness for no vacuum leaks.
Maybe theres crap in that bottom half and all my "cleaning" just disturbed it and
pushed the crap further into the clogged up small spaces. The hesitation doesn't happen every time either. If I give it gas while it's just idling it hesitates, but if i immediately- within two or three seconds- give it gas again, it doesn't hesitate. I'm about to take it apart completely and really clean that crap out. Terrible mental imagery of clogged up crap right now.

 

Sounds like the accelerator pump check ball is hanging up.
There may be some debris or varnish in the passage.

If you operate the lever by hand can you see a strong flow of fuel in the throttle bore?

 

That's where i think the problem was. I re-re-rebuilt the carb and i'm about to fire it up. I found that the places that i had just cleaned this morning were already clogged again so i cleaned the ENTIRE thing this time. There must have been more crap deeper in the carb that recirculated through the rest of the carb. I'm about to see how it runs now.

 

What the hell is wrong! I cranked it for probably thirty seconds. It started up with a very weak idle and i gave it gas until it evened out.. once it was running on its own I readjusted the idle screw a little bit to give it a stronger idle. Then it started doing the same hesitation thing. Weak at first but it got stronger and stronger until the engine had been running for two minutes and the hesitation was back to being just as bad as this morning. What else is there? I did everything! Is the new filter interfering with fuel flow??? what could it possibly be??

 

Sounds like the choke needs to be adjusted.

I say "sounds like" because there's no way for anyone to truly diagnose it over the internet.

 

Yup. Well I'm going to get into some re-adjustments tomorrow. But you do have good diagnosis skills because i just went for a ride once my truck was running hot without the choke the hesitation was much less, almost gone but still there slightly, I know the choke also has many adjustment specs in the rebuild kit manual too. Thanks

 

Check the filter again. Take it out of the line and dump it in a pan and see how much dirt is in it. If it's full of dirt, you are going to have problems till you replace the gas tank.

 

sounds like a rich spot, do to , debris , or misadjusted choke , or a vacuum leak , check the throttle shaft for looseness , or a miss adjusted accelerator pump causing a lean spot when you "tip" in to the throttle , very common on carter yf/a carbs. old ones especially

there is a lot of small passages in these carbs ,

try carb cleaner in the brass vent tube at the top of the air horn spray about a 5 second shot of that while running and rev it up after the spray or when it bogs , to run through most if not all the passages

the choke should be almost completely closed , just a very small crack it the opening

, some more or less (some fully closed , some 1/2inch open ) that is try and error

many variables

 

Thanks tomorrow i'll check the filter and try some more cleaner if it's not the tank. I'm leaning towards tank replacement right now judging by all the crap ive seen coming out of the lines. Also, the problem is intermittent and didn't develop until days after the initial rebuild. One question i have about a misadjusted carb- What adjustments (or misadjustments) can i make to the accelerator pump? would this be the metering rod adjustment? ..The rod attached to the pump diaphragm shaft that gauges flow through the main jet? I think i set it right but might want to revisit. And i'm going to need an electric choke with an adjustment mark on it because mine doesnt have one so i reset it to where it was in the photo i took before rebuild. I've got plenty of leads here though thanks

 

the accelerator pump , is the metering rod , pump , all in one , you HAVE to un screw the idle speed screw all the way out, for the throttle (butterfly) to be closed all the way ,then you can adjust the pump diaphragm,

pump adjustment , unscrew the screw on the assembly of the pump link ,then press firmly on the diaphragm rod until it bottoms , tighten the screw until it touches the link then 1/4 to1/2 turn more should work maybe more ,(a universal adjustment ,in diagrams ) if it hasn't been adjusted correctly it can cause a stumble

but , you are on the right track , gas tank should be checked with constant gunk showing up nothing big really

 

OK ill recheck the metering rod adjustent if nothing else works but i had originally done it like you described. Its looking like the choke though i still haven't rechecked the fuel filter. The hesitation and low idle problem only appears during warm up right now and I have a new automatic choke coil coming in the mail, one with a mark. Tomorrow on my break I'm gonna take the air cleaner off with some coworkers and give it a good collaborative brain storm.

Hey I got a question is the thing that the carb sits on top of part of the intake manifold or does it come off? what is it? I was tightening the carb onto the the two hold down bolts and one of them started spinning with the nut like it was broken. I got the carb nice and snug for now still but i'm pretty sure that's either gonna come loose while driving or come straight off when i take the carb off next. I had already figured that the thing is leaking at a gasket and it looks like a vacuum port is clogged it could use some service anyway but now i'm really going to have to get a new one or something.