Learn me: mechanical fuel pump and carb

So I bought a 1950 Willys CJ3A with a 70s Buick engine and its carbureted. My lack of knowledge is that I haven't had a carb in 20+ years and it was on an old VW with an electric fuel pump. My issue with the Jeep is that it is extremely hard to start, but once up and warmed up seems to run fine.
 

Example 1, yesterday my son had to be at practice at 7. I went out and tried to start the Jeep and after several cranks it sputtered a little but wouldn't run. I got pissed, hopped in the truck, drove him the 5 miles round trip to practice and came home. I tried the Jeep when I got home and it cranked first try and ran fine. I drove it to run errands over the next  without issue. 
 

Example 2, after starting and running when I cut it off and go to start it again 5-10 mins after stopping it runs fine. If I wait 30 mins to an hour, it sputters and idles funny. And if I try and drive it too soon, it stalls and dies in first gear. 
 

It is currently running on nonethanol gas. I do not see any crud/rust in the bottom of the tank. I can access the fuel filter and pump fairly easily. The tank and lines seem solid and I can't find any leaks. The fuel level sender unit gasket on the top of the tank  could probably be replaced. The sender replaced as well. I've asked around on the local Jeep and Willy's club to see if someone with experience could help. I'd really like to know what is going and how to fix it and not just take it to a shop. 
 

I will take any and all suggestions as to what to check. But I may need to know how to check them. Thanks 
 

In reply to octavious :

The float bowls should hold enough fuel that it'll restart and run off that until the pump catches back up.  Suprang can sit a few weeks and it's jump in pump it three times and it starts right up.  Suprang also has a brand new fuel pump and carb on it.  I like to have a fuel filter right before the carb so that I can see what's happening in these situations/

Does it have a functioning choke?

Jesse Ransom said:

Does it have a functioning choke?

This plus . . . 

Has it been sitting for an long period of time?

Are there any rubber hoses? If so how old?

Which carb does it have?

Jesse Ransom said:

Does it have a functioning choke?

It has a choke lever that when you pull moves a lever on the choke. I've tried using it to start it but it doesn't seem to help. 
 

It sat for a few months up until last weekend when I picked it up. I drove it everyday but Weds this week. 

At this point all we know is you have a swap (I don’t know if it is/was a common one) of unknown origin or quality. Plus we have not been told the brand or number of barrels of the carb.

Re the choke: the lever moves a plate at the top of the carb. Are you pulling the cable all the way or partially? Is that plate closing off the air flow partially or completely when activated? A picture would help people to visualize this.

Are you giving the gas pedal 1 pump or 10 before you try to start it?

Is there a squirt of fuel when you actuate the throttle by hand? 

Is the fuel fresh or unknown?

Is the fuel filter new or unknown?

Remove the air filter, Look down bore of the carburetor, pull the choke look again and see if there's a flap in the way.  If so, choke works.   A choke cuts flow of air to give a thicker gas ratio.

Next I would remove the top of the carburetor flip it upside down and see if the float bowl is actually high enough or too high or too low.  Hence not enough gas in the bowl to start it cold.

Sorry was at a swim meet all day.
 

Supposedly a Buick V6 from the 70s. The swap was pretty common because the carb cleared the flat hood without having to cut a hole like other hoods. 

Fuel is fresh.

Fuel filter is unknown. 
 

I've never pumped the pedal before starting (didn't know I needed too)

Is there supposed to be a squirt of fuel when I operate it by hand? I don't know. I can check 

You have to get past your fuel injection habits. You almost always have to pump a carburetted car before starting it. One or two is usually a good starting point. Doing that should be a game changer for you. It's just what old cars required before electronic fuel injection.

Further, your choke will not close and engage fast idle unless you pump the pedal. You have an electric choke on that carburetor. The choke will take care of itself if you'll give the accelerator a pump or two before trying to start it when it's cold.

There is some added-on cable setup on the carburetor on the driver's side near the accelerator cable My suspicion is that any pull handle you have on the dash is likely hooked up to that for some fast idle or hillbilly cruise control or something. At this juncture, probably best to just ignore any choke handles or pull levers on the dash.  

You're gonna want to fashion some sort of vacuum plug to put over that exposed bib on the passenger side of the carburetor too. Either use a vacuum plug or even a short length of appropriate size hose with a little screw struck in it.

octavious said:

 

That looks like a 2 barrel Rochester carb.

Re the choke: earlier you said “It has a choke lever that when you pull moves a lever on the choke.” Where is that choke lever?

That does not equate with what the picture shows which is an electric choke. The red wire, if hooked up, heats a metal coil in the round black piece which moves the choke plate. Is the red wire hooked up to anything we cannot see?

Normally, if all is working / tuned well, you would pump the pedal once or twice before starting.

Yes there should to be a squirt of fuel when you operate it by hand. You are simulating what the gas pedal does when you drive the car.

To add on to that very last bit of that last post, what you're doing when you press the pedal is engaging an accelerator pump whose job is to shoot in a little extra fuel to cover what would be a lean condition when you suddenly let extra air in until the rest of the carb catches up. As a bonus, that can chuck a little fuel into the plenum to help with cold start.

But getting the actual choke engaged should help with cold running as well as starting.

I don't miss carburetors.

On the boat (454s with quadrajets and mech fuel pumps), the start sequence is 3 pumps on the throttle to dump the accelerator pump, leave the throttle cracked (high idle cam should do this for you on an automotive carb), then crank it.  It should fire right up.  However, if it's been sitting for more than a week or 2, there may not be enough gas left in the float bowls for an easy start.  In that situation, you do the cold start sequence, if it doesn't start after a few seconds, give it a couple more pumps on the throttle and try again (it'll start).  If you know it's been sitting for a while, just crank for a few seconds first to get fuel to the carb, then do the normal cold start process (that usually leads to things starting right up even after sitting for 5 months over the winter). 

If you don't do the proper start process, you'll often be cranking for a while before anything happens, especially if it's cold outside. 

This all assumes the choke is properly working and adjusted, of course. 

In reply to Cousin_Eddie (Forum Supporter) :

The choke cable probably went to the original carburetor.  It's likely not doing anything now.  

You guys are awesome!!! Thank you all so much.

The photo with the arrows, when I turn the key there is a small plunger on the blue arrow that goes down and then comes back up. The red arrow points to the cable that is labeled "choke" inside the Jeep. When you pull the cable it operates the piece at the yellow arrow. 
 

The black rubber hose to the left of the valve cover does not have a plug in it. Does it need one?

And I think that is the part number. 
 

I'm working to plug the port on the passenger side now 

17058182 is a Rochester 2GC or 2GV carb part number

1705 is a carb made after 1975 and before 1980,

8 would be 1978,

1 indicates 2-bbl Federal emissions,

8 indicates the GM division it was to be used for,

2 an even number here usually indicates it was for an automatic trans car.

I see a pivot on the linkage possibly for a kick-down.

The red arrowed cable is most likely as Eddie stated: “some fast idle or hillbilly cruise control or something.” Not the choke.

It took 3 sequences and is idling really rough. Then it died and took one more sequence and is now idling better.

How many pumps are you giving it?

Have you checked the accelerator pump?

Have you checked how much the choke plate is closing?

Have you checked the timing, plugs etc?

The vac line under the carb part number looks deteriorated.

L5wolvesf said:

How many pumps are you giving it?

Have you checked the accelerator pump?

Have you checked how much the choke plate is closing?

Have you checked the timing, plugs etc?

The vac line under the carb part number looks deteriorated.

I took it for a drive and it was a world of difference. Never stalled. Idled much better and higher. Seemed like a different Jeep!  I didn't have a chance to restart it. But I will try that next. 

3 pumps crank. Rinse and repeat.

No on the accelerometer pump.

Is it closing? I looked to see if it was moving but I did not take a measurement to see how much it is closing. 

I have not checked anything else.

When you say the vac line, you mean the one belwow the one that I just plugged? 

Ideally it should be 2 or 3 pumps crank and fire up. No rinse / repeat. That could be the accelerator pump being not as good as it should be.Remove the air cleaner check the squirt. At the same time you can check the choke plate. No measurement - just see how much it is closing. 

I see 2 black rubber vac lines under the carb part number. One is broken off and both look deteriorated. Vac lines are cheap to replace.

I've read some half correct, and therefore half incorrect, responses. Here's the deal:

If the carb is working properly, and it probably isn't, more on that below, on a cold engine, you cycle the gas pedal ONCE, to set the choke. All the way to the floor and all the way back up. Then open the throttle part way and crank. Be patient. If you haven't driven it in a while, it might take up to 10 seconds to start (if the fuel pump is in good shape). No extra pumping! Don't move your foot. Be patient. The movement of air past the venturi will draw fuel from the carb into the intake manifold. You do not need to use the accelerator pump. The engine will start and run at fast idle. Let it run there for 2 minutes or so, then stab the gas pedal and see if it starts to kick down. Alternatively, if everything is properly adjusted, you can drive immediately.

In your Example 1, you said that the engine started fine after you got home, which was after you had cranked it earlier. It started fine because you filled the bowl when you cranked it earlier. Earlier, when it sputtered, the choke probably wasn't set.

In Example 2, first sentence, you experienced the same situation as when you returned from practice. The bowl was full so it started quickly. In the second sentence of #2, it sputtered because you didn't reset the choke and the engine cooled off a bit. In the third sentence of Example 2, it stalls and dies because you didn't warm it up all the way, AND the choke pulls off too soon because it's old and the spring has weakened. It's also likely that the seal on the accelerator pump is old and stiff, which will cause a bog that can stall the engine.

Things to do:

1. Make sure you have fresh gas.

2. Use the proper starting sequence that I mentioned above.

3. Tighten up on the choke spring a very little bit at a time. Start the engine when it's dead cold and drive it immediately. Cold drivability should improve. If it's better but still not right, let it fully cool. like overnight, and repeat. It will never be the same as when it is warmed up like an FI engine is, but it should be totally drivable and reasonably smooth when cold, just a bit down on power.

4. If #2 works, but you still have a bog when accelerating from a stop, get a new accelerator pump. They're cheap and not too hard to replace.

5. If you experience hard starting and bad idling on a fully warm engine that has sat for a short period, like 10 minutes, that's probably a little bit of vapor lock. Start it again and run it at higher RPM for a few seconds until it runs smooth, than let it idle.

If it runs fine on non-ethanol gas, and it probably does because that is what it is likely calibrated for, there's a good chance it will run like crap on gas with ethanol. Be ready for that if you go someplace where you can't find non-ethanol gas. Be ready to richen the idle circuit by turning the idle mixture screws until it runs better.

Source for all the above: I've had a bunch of GM cars with carbs and have been relearning all of this over the past 3 years with my '77 Grand Prix.  Even after doing all the above, it still idled just a tiny bit rough. And then I drove it some more and it's perfect now. Engines need to be used. Try do drive the Jeep every 2 weeks or so, long enough to fully warn it up.

My wife's car went into the shop for some paint repair after she got tapped on the rear fender a few weeks ago. So I had to start the Jeep and move it into the garage. 3 pumps, slight push on the  throttle, turn the key, and she fired up. I let her warm up and then took her for a 20 mins cruise. Parked in the garage now.

Not sure I'll get to drive it for a few days, due to work and travel so I'm interested to see what it does when I'm back.