Looking For Yf Experts To Help Figure This Out

I'm at my wits end with this problem and looking for experts in these old carbs for suggestions. I know this is long but I'm trying to give as much info to help figure this out.

Here is the background. A couple years ago I sent the carb off the J&J Carb in CA for a full restore. Mike at Mike's carb recommended them for a full restore. It came back looking great. I installed it and it ran fine. I had the Pertronix installed about the same time. I had NO issues with acceleration, hesitation or anything, including accelerating up highway hills. Life was good. Then I had the engine trouble and pull it to have rebuilt. When I got it back things were back to normal, until the engine started making noises at 200 miles. Pulled the motor again and the rebuilder found bearing trash and made good on it. But during this process, the carb did sit for several months waiting. When I put everything back in, the engine is now fine with over 500 additional miles on it. But since putting it all back in, I've been fighting this stumbling and hesitation on acceleration, especially when under load likes those same highway hills I had no problem actually accelerating up before. I thought maybe gummed up carb so I ran a can of SeaFoam. Tried premium gas. No help. All fuel lines have been replaced with new ones from Walcks, before this started. Fuel pump is new from before this started. Up to this point, the carb was exactly as when I got it back from the restore and when it was fine.

At one point I have verified TDC, and timing at 5 degrees before. I have verified the cap, rotor, wires and coil. It idles as smooth as a kitty purring. I even had the distributor check by a speciality place and they verified all was good as far as bushings, etc., no play at all. They did say the advance springs were very dirty and would stick some, so they were cleaned. I have verified with a timing light that the advance does advance as I rev the engine. I really don't think it's an electrical issue as it idles great and no misses or anything while normal cruising.

I don't think it's a vacuum leak as I disconnected everything except the PVC line, which are all new from before this started. It doesn't help, so I eliminated that. I have replaced the carb to manifold gasket, just to be sure. I see no difference.

But when I try to accelerate, even from stop, it sputters for a few seconds then gets going. I can run the gears up to 3,000 rpm with no hesitation, other than the initial sputtering. I see no fuel spilling out anywhere. At one point I opened up the carb and saw a little debree at the bottom of the bowl, so I took it apart and cleaned every thing with carb cleaner and assumed that was the issue so added a fuel filter today. I did also discover that the check ball did not have the weight on it. That was the way it was returned from J&J and did work at one point. I've since ordered the full premium kit from Mike's and they told me that the check ball by itself is not right so I added the little weight from their kit today after cleaning everything again. Again assuming the weight and filter would solve it, but it did not. I did also notice that the float was different from the one in their kit. The float I have in, (assuming it was either there originally or put in by J&J), has a sloped bottom on one end. Mike's says that's a float out of a YFA and may work but technically not the correct one. The one in their premium kit that I got does have the correct one which is flat across the bottom. Tomorrow morning I'm gonna change that out and make sure it's level is set right according to Mike's video, but I'm not optimistic that is the issue since the other float was in there when it was working fine. The needle and seat look fine and appear to be working correctly.

When it does the stumbling, puffs of dark smoke do come out of the tailpipe, but just when stumbling. That is what leads me to believe it's carb and something possibly with a setting with the accelerator pump. I have checked it and don't see any tears, cracks, etc., but did put the new one in from the Mike's kit.

Is there any other settings I'm missing. I've checked and blown out the tubes and jet. Is there some special setting to the metering rod? I'm at a loss and heading to the Coloardo Fall Colors Tour Saturday, so I need to get this figured out quickly. Any and all suggestion appreciated.

 

I've watched Mike's video on this several times along with reading the E-16 section of the FSM and think I understand it. In the morning, first thing is to just double check the intake manifold bolts to make sure no leak. Then pull the damn carb again and do his test of the accelerator pump to make sure it's squirting right. Then pull apart and put his float on and adjust. Then see about checking that metering rod adjustment. I didn't check it before, assuming it was set correctly by J&J. Then I thought about me changing the pump so I need to recheck that rod adjustment. Gonna also double check coil numbers too. If that doesn't do it, then get my shotgun out. I guess double check fuel pump pressure,then shotgun.

 

One thing that can happen to YFs is that over-tightening the mounting studs can bend the carb base flange ears - then it leaks vacuum and more torque-ing will only make it worse. Check the base for flatness.

Also, have you ever hooked up a manifold vacuum gauge to see what it tells you?

Occasionally bad ignition points or excess gap in the spark plugs can mimic a carb problem, under acceleration load. You say you have pertronix, but it's just a thought.

 

Update. Bottom of carb is flat, gasket is correct so the vacuum is there. Switched out the float and adjusted it. Found the metering rod was NOT bottoming out so did a slight adjustment on it. Not sure it totally right but did what I could. Took it for a spin and much much better. Still does the stumble every once in a while. More testing.

 

Well, on another run out it really started shuddering but got back to the cabin. I did notice no fuel in the new plastic filter and I know I watched it fill yesterday. It still runs but not filling the filter. In fact I don't see any gas coming in even after I rev it up. Not sure how long it takes to use up what's in the bowl but I let it run for a good minute with no sign of fuel going in. First going to check all connections on the new filter to make sure not sucking air somewhere. But I'm thinking fuel pump may be going out now. I did happen to bring my NOS AC glass bowl pump so going to swap it out if all connection good. I hate last minute issues.

 

Well got here (in CO) for the Fall Colors Tour Saturday and have had an up and down with the issue. The sputtering just kept getting worse. With warmer the engine got the worse. I did fill up with the premium no ethanol gas as recommended for the altitude. Found an old school mechanic here with the same carb saying he had experienced the same type of things. We pulled the carb and he adjusted the metering rod, but I thought could have been a little more, but deferred to him. And it was substantially better. Then started on a short excursion with 15 or so Willys and it started sputtering again. So I headed back to camp, pulled the carb and gave it just a little more adjustment. Took it out and the sputtering was gone. Great solved the problem so the wife and headed out on our own and it felt much better, then all of a sudden bucking like getting then not getting gas. Then it just stopped. Would not start, so I looked under the hood and the filter bulb was almost dry. Couple minutes later it finally started and ran but rough, then another mile later fine again. We did make it back to camp, but I decided enough was enough. Not having fun. I've decided not to spend another late night swapping fuel pumps, being greasy and camping like that so we head back in the morning. At this point, maybe something is sloshing around in the tank that clogs the pickup, or fuel pump being intermittent, or what I'm not sure at this point. So missing another year of trail ride at the tour. The hunt continues.

 

You could try blowing out the fuel line from the engine back to the tank. You will hear bubbling in tank when it is clear.

Also trying running with the fuel cap loose to be sure the tank is venting.

 

This last test run when I topped off the tank, it started doing it and while driving I reached down and did that very thing just loosening the cap to be sure and it did not help. When I get back to the cabin, the first thing I'm gonna try is using the air tank to blow back and then drive to see if it helps, but of course if something is blocking, blowing back will just be a temp thing as it's still in the tank. Just not sure I want to pull the tank while at the cabin without a garage and working in the dirt and grass.

 

On the trail I've done it just by mouth.

 

Here is a story that may lead to what the problem is. My first jeep was a DJ 3, a two wheel drive Dispatcher. I put a new gas tank in it, a new fuel pump, and put the sending unit in the tank with a screen on the fuel pick up, using silicone sealer. I put gas in it before the silicone hard, the silicone got mixed with the gas and collected on the fuel strainer on the pick up. The Jeep would drive fine, then just stop running, no fuel in the carb. I would take the fuel line off, and blow air backwards thru the fuel line, and boom, it fire right back up. A little farther down the road the same thing. I made an air hose that would hook up to a tire and blow air back through the fuel line and clear it, for a while, then the same thing. Finally I pulled the pick up out of the jeep and found a balloon on the screen, made by the silicone, problem solved. My C J 5 is gravity fed, so there is no pick up in it, but if you used silicone sealer it may be part of the problem. Good Luck

 

Fuel lines. Steel or rubber? If rubber how old? Old rubber cracks, letting air in. You won't see fuel leaking. If you have been using ethanol in the past, the rubber lining will swell and cut off fuel flow. Dirty tank, bad gas, water in the gas, all are possibilities.

 

Just for clarification the lines are all new. The vibration line is new. I have replaced the tank float as it had a hole (plastic). While the top was off, I remember looking inside and thinking it was I great shape. So I have not pulled the tank as of yet. After the tank, all is new.

Now for the odd part. We got Willie back to the cabin and have done nothing to it. It seems to run fine. I've driven it around til it warms up and still fine. Took some hills and fine. The cabin is at 7,000 and in CO we were only at 8,000 so I don't think that's it. Crazy how this is. Going to just keep driving it for now. Venturing further each time.