Carb novice looking for help

[DrDoc]

A few weeks ago I started having stumbling and hesitation under acceleration (very jerky, almost dies, sounds horrible), and it's gets worse the warmer the engine gets. At idle it seems good and under no load it revs fine.

I had been meaning to do it for some time, so replaced the plugs, wires, and installed the larger Ford cap and rotor. I also checked timing (8 deg) and adjusted the idle mixture to get Max vacuum, all with no change. Last night when I got home I shot starter fluid around thinking I had a vacuum leak but didn't notice any changes in idle.

I had installed one of the eBay 2100’s last summer and had not had issues like this until a few weeks ago.

Any thoughts before I cave and take it into the shop?

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[Torxhead]

You could have an issue with the carb accelerator pump which shoots raw gas down the carb throat. Possibility out of adjustment or a leaky pump diaphragm.

 

[DrDoc]

You could have an issue with the carb accelerator pump which shoots raw gas down the carb throat. Possibility out of adjustment or a leaky pump diaphragm.

My old Carter had an issue with that before I replaced it, but that one would stumble right away even with no load so I assumed that wasn't the issue this time. I get a good squirt of fuel when I pump the throttle, how else can one test the pump?


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[Lumpy Grits]

I would first check your fuel filter. Does this filter have the return line? Is the return line at the 12-o'clock position?
Have you confirmed the float setting in the carb is still correct.
Have you ck'd all the bolts/nuts on your intake manifold.
What is your vacuum reading? How steady is the needle?
Can you post a picture of the carb setup on your jeep?
2100's have a well earned rep for vacuum leaks at their base.
Use some VERY soapy water in a spray bottle for hunt'n vacuum leaks.
LG

 

[jafo]

Ok. I have went through something similar. I kept my original carb and with the advice formentioned decided to take a closer look at mine knowing there is an adjustment on the accelerator pump linkage. Sooooo, grabbed the old carb and seen there is more than one adjustment. There is one at the point of the pump you can visually see no problem, but there is also an adjustment back by the throttle linkage. It has about 4 to 5 holes. My original is set in the top hole. The reman carb I got from ebay was the second hole down. That would give it slightly less fuel than the top hole. So I switched it to the top hole. So far so good. I was even getting a lean pop under load from a stop only on acceleration. Check youra out and see which hole your accel pump linkage is set in.

 

[elwood blues]

A few weeks ago I started having stumbling and hesitation under acceleration (very jerky, almost dies, sounds horrible), and it's gets worse the warmer the engine gets. At idle it seems good and under no load it revs fine.

I had been meaning to do it for some time, so replaced the plugs, wires, and installed the larger Ford cap and rotor. I also checked timing (8 deg) and adjusted the idle mixture to get Max vacuum, all with no change. Last night when I got home I shot starter fluid around thinking I had a vacuum leak but didn't notice any changes in idle.

I had installed one of the eBay 2100’s last summer and had not had issues like this until a few weeks ago.

Any thoughts before I cave and take it into the shop?

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I wouldn't go fiddling with the carb if this is a recent change. If it ran up until a couple weeks ago, I would think that you've got a piece of debris either in your gas filter, or in the venturi tubes, or even in a vacuum port of vacuum run in the carb somewhere. I could also imagine the power valve going bad, it's just a simple spring loaded setup, they're only $10 or $12 to replace, Holley power valves fit 2100 series carbs. The correct power valve should be 1/2 of your in/hg @ idle.

 

[DrDoc]

I wouldn't go fiddling with the carb if this is a recent change. If it ran up until a couple weeks ago, I would think that you've got a piece of debris either in your gas filter, or in the venturi tubes, or even in a vacuum port of vacuum run in the carb somewhere. I could also imagine the power valve going bad, it's just a simple spring loaded setup, they're only $10 or $12 to replace, Holley power valves fit 2100 series carbs. The correct power valve should be 1/2 of your in/hg @ idle.

The power valve was one of my thoughts since it's fine at idle and revving with no load. I'm completely green though when it comes to carbs, where is it and what do you mean by the 1/2"?


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[Lumpy Grits]

Look at Youtube.
https://www.youtube.com/watch?v=h4J4QhNDj6Y

LG

 

[elwood blues]

The power valve was one of my thoughts since it's fine at idle and revving with no load. I'm completely green though when it comes to carbs, where is it and what do you mean by the 1/2"?

Not 1\2", half of whatever you measured your idle vacuum to be. If you measured your vacuum at idle at 17 in/Hg, you should get a 8.5Hg power valve.

Holley Power Valves | JEGS

 

[DrDoc]

Not 1\2", half of whatever you measured your idle vacuum to be. If you measured your vacuum at idle at 17 in/Hg, you should get a 8.5Hg power valve.

Holley Power Valves | JEGS

Got ya, that makes a lot more sense. Like I said, novice. I will be heading out to the garage today to replace the fuel filter and check a lot of the stuff Lumpy mentioned. Will post pics of my setup and current vacuum at idle.

Side question, is getting max vac at idle the best way to set idle mixture? I have read a couple of threads that said doing that will be too lean. Like I said, I will check again once I get out there, but believe I had 19.5 in/Hg when I set the mixture a couple weeks ago...

 

[elwood blues]

Got ya, that makes a lot more sense. Like I said, novice. I will be heading out to the garage today to replace the fuel filter and check a lot of the stuff Lumpy mentioned. Will post pics of my setup and current vacuum at idle.

Side question, is getting max vac at idle the best way to set idle mixture? I have read a couple of threads that said doing that will be too lean. Like I said, I will check again once I get out there, but believe I had 19.5 in/Hg when I set the mixture a couple weeks ago...

Don't worry, most of us were (some still are, others just pretend we aren't ) novices at some point or another. That's what we're here for, to help each other out and to learn.

I do not believe that getting max vacuum at idle is the best way to go. From what I've read, and had people tell me, you should set your timing with a timing light, 8-12° BTDC is pretty standard for a AMC 258 i6 / 4.2l . Then you adjust your carb using the vacuum gauge, mess with the idle air mixture screws, to get max vacuum.

If you just go off of max vacuum for your timing, you'll be too lean at higher RPMs.

 

[DrDoc]

Here are some pics. I noticed the grime around the power valve right under the acc pump, could that be something? It seems to be centered around the seal of the power valve cover.

DrDoc

 

[elwood blues]

Here are some pics. I noticed the grime around the power valve right under the acc pump, could that be something? It seems to be centered around the seal of the power valve cover.
DrDoc

That could absolutely be your culprit, that grime build up is probably from a leaking gasket around the power valve, allowing just a tiny little bit of gas out, and that moisture is collecting dirt.

The cause could be just the gasket, or the valve caused the gasket to leak. Either way, a new power valve comes with a gasket.

 

[elwood blues]

A couple of things I noticed, you should cap off that port of your EGR valve, that's a vacuum leak. Also, on the top horn of your carb, that open spot is a bowl vent breather, I don't remember if that has to have something in it or not. But, you can put a little piece of copper pipe in there and cap it, or run a hose to your charcoal canister.

And on this one, see the gunk between the top horn and the base of your carb, there's another gasket leak. Possibly just tightening the screws on the top horn will help this, just clean it all up first.

The other one, that's the electric hook up for you choke. If you run +12v wire to that terminal, just make sure that it turns off when you turn the key off, that will help the choke warm up faster.

 

[oldyeller]

I had the same trouble you did, most of the symptoms that were brought up would happen immediately and not wait till warm up. my jeep had been setting up for a while and it would run great until it warmed up then when I would stop and unload the engine it would run very rough and die. It happened to me the last time while I was getting gas. I looked around and felt the underside of the egr valve. There are slots that you can reach your fingers into. I felt that it wasn't moving freely and was in a bind, I nudged it and it sprung into place and the engine fired up and made it home. I immediately saturated the diaphragm with penetrating fluid, hilco lube, and it hasn't happened since. Some may say that this shouldn't happen but I was ready to try anything. I rebuilt the carb 3 times,checked timing, vacuum, changed vacuum lines, etc. it is so easy to check and it want hurt to pull the vacuum line and squirt fluid down it and just let it soak.......if you have deleted your egr, disregard the above and good luck.

 

[DrDoc]

I had the same trouble you did, most of the symptoms that were brought up would happen immediately and not wait till warm up. my jeep had been setting up for a while and it would run great until it warmed up then when I would stop and unload the engine it would run very rough and die. It happened to me the last time while I was getting gas. I looked around and felt the underside of the egr valve. There are slots that you can reach your fingers into. I felt that it wasn't moving freely and was in a bind, I nudged it and it sprung into place and the engine fired up and made it home. I immediately saturated the diaphragm with penetrating fluid, hilco lube, and it hasn't happened since. Some may say that this shouldn't happen but I was ready to try anything. I rebuilt the carb 3 times,checked timing, vacuum, changed vacuum lines, etc. it is so easy to check and it want hurt to pull the vacuum line and squirt fluid down it and just let it soak.......if you have deleted your egr, disregard the above and good luck.

I don't have it hooked up to vacuum but it's still there. The EGR was one of the things I was thinking of.

Right now I am trying to get info from Gronk about which rebuild kit I need but he's gone silent for the past 5 days. Anyone know which make/model the 2150 he sells is setup from?

DrDoc

 

[elwood blues]

Ford Motorcraft 2100 2150 2 barrel carburetor Parts Page

https://quadrajetparts.com/ford-2100-2150-carburetor-parts-c-410_413.html

Autolite Motorcraft 2100 Carburetor Kits & Parts

I'm not sure what specific rebuild kit you'll need, but a couple two of these places just sold gaskets.

 

[oldyeller]

There are generic kits at parts stores that cover 2150 and 2100. There is one guy online that rebuilds carbs and sells specialized kits that are model specific. This guy also said there has been an influx of "motorcraft" fakes from china. So if you have bought one recently and it was very inexpensive you may have been bitten by one of these cheap carbs. Like all the other guys I would dive in, strip it down and you will eventually find it. There is a lot of good help here and I have a repair manual that is really helpful. I took my carb apart and found it missing a small weight in the Venturi it looked like a small piece of round stock and it was sold by the guy I spoke of earlier but that detailed of a kit was about twice as much, so I just made several and tried them. Good luck.

 

[DrDoc]

So my fuel economy has gone down by 3mpg the last couple weeks. Would I be correct in assuming that this points more to a bad or failing power valve? Am planning to pull a plug tonight to take a look as well to try to verify.

Since Gronk has gone silent on my emails, what are the differences between all the kits on http://www.carburetor-parts.com/2150-Carburetor-Kits_c_571.html, which would be my best bet?

DrDoc

 

[oldyeller]

The link you have is the guy I was talking about. He also has how to videos online. Your mpg drop could be from anything. Just start the troubleshooting
Process. Will look at the kits a little later. Xmas shopping now. What fun