Vacuum-Emissions???

[dslywalker]

IO, you spoke of too much pressure going into the carb with no vent line hooked up. I'm thinking out loud again, but could the PO have been using the bigger filter to help relieve the pressure going into the carb, since he did not have a vent line connected. Would a big filter like the one he was using accomplish this????

I would just build up pressure in that one also.It would just hold more gas in the filter and more filter area.
I was beginning to wonder if you had a defective fuel filter from the start.If that filter has to be turned upward I would think there would be some type of baffling inside the filter to prevent full flow to the return line.I've read articles where it has to be turned the other way 1/4" down 5/16 up but the FSM contradicts that so
I looked at mine this morning.There is a check valve or something with a crosspiece inserted and swagged in the fuel line that runs along the frame at the engine bay point.

 

[dslywalker]

I think one of the gauges is off.At 1800 rpm your motor would be running pretty fast.Does the oil gauge go up when you rev the engine.Does it sound like 1800 rpm?Idle is around 750 so it would be a little over twice as fast as a idle.
There's a oil sending unit down by the oil filter between the filter and firewall.You should see a 1 1/2" round metal sending unit there screwed into the engine block.See if the wires are attached there.It will be if its still stock.It looks like it from the pic.Can't see if the sending unit is there from your pics.
Looking at your pics again it still looks to me like fuel filter still needs to be turned up a little more.Unless you changed it since or my eyes are shot.

 

[RanchGirl]

I would just build up pressure in that one also.It would just hold more gas in the filter and more filter area.
I was beginning to wonder if you had a defective fuel filter from the start.If that filter has to be turned upward I would think there would be some type of baffling inside the filter to prevent full flow to the return line.I've read articles where it has to be turned the other way 1/4" down 5/16 up but the FSM contradicts that so
I looked at mine this morning.There is a check valve or something with a crosspiece inserted and swagged in the fuel line that runs along the frame at the engine bay point.

IO asked me if I had reversed the filter, but I have not given that a try. This weekend, I think I'm gonna give it a try, 1/4" down & 5/16" up, just to see what happens or if it makes a difference. The filters are cheap, so I may go ahead and purchase another one and give it a try to eliminate the defective filter scenario. I'm also going to trace out that entire return line if I can, to see if anything appears out of the ordinary. Not sure I can recongize the "out of the ordinary" but the reference material you guys have shared will help me.

Also, I don't know if this will help or not with the trouble-shooting, but here is some information on the carb.

Carter Carb #0-2681; There is also a blue tag on the carb that has the following information stamped on it: 8349S and C229A

 

[RanchGirl]

I think one of the gauges is off.At 1800 rpm your motor would be running pretty fast.Does the oil gauge go up when you rev the engine.Does it sound like 1800 rpm?Idle is around 750 so it would be a little over twice as fast as a idle.
There's a oil sending unit down by the oil filter between the filter and firewall.You should see a 1 1/2" round metal sending unit there screwed into the engine block.See if the wires are attached there.It will be if its still stock.It looks like it from the pic.Can't see if the sending unit is there from your pics.
Looking at your pics again it still looks to me like fuel filter still needs to be turned up a little more.Unless you changed it since or my eyes are shot.

The motor was running pretty fast. I'm not sure it was 1800 rpm fast, but I did have the idle turned up a little too high. I will turn it back down this weekend and target the 750 rpms for idle. I really didn't rev the engine up much when I noticed the oil pressure so low. Guess I was afraid I might damage the motor. I will rev it up and see what the oil pressure does. I will also check out the oil sending unit you described and make sure the wires are attached. I did go back an check the fuel filter after you saw the pictures and mentioned it didn't look like it was turned up enough. It wasn't turned up as much as it could have been so I repositioned it, but got the same results.

 

[dslywalker]

That SUX.We'll keep on plugging away nothing like a challenge

 

[dslywalker]

Here's a link in the doc section of the forum.It's the parts manual,it can come in handy if you haven't found it yet.
Jeep Parts Manual 81-86.pdf - Jeep-CJ Documents and Manuals

 

[dslywalker]

If you look at figure 14-3200 part #8 under the fuel group their showing a valve clamp in the fuel filter return line.Also parts manuals being what they may there showing the filter returnline on the bottom.Hmm
Anyone know what that is

 

[RanchGirl]

If you look at figure 14-3200 part #8 under the fuel group their showing a valve clamp in the fuel filter return line.Also parts manuals being what they may there showing the filter returnline on the bottom.Hmm
Anyone know what that is

WOW, I think you're on to something. I can use this drawing to trace down my return line. I can't really tell what that valve clamp is though. It is interesting that they have the vent line on the bottom. What the heck, when I get home I'm gonna turn that bad boy around and see if it makes a difference.

 

[dslywalker]

Did your lines go back on the tank like this.Then found another section on fuel filter in the book return line up small barb.
Not very good scan my finger showed up good on the bottom
I was just thinking maybe the sending unit in the tank had a orfice in it for fuel restriction.Thinking again you might look in the opening of the fuel filter on the 2 sided part and see if you can see a restricting orfice in there.They need a grasping at straws smilie:drool:

 

[RanchGirl]

Did your lines go back on the tank like this.Then found another section on fuel filter in the book return line up small barb.
Not very good scan my finger showed up good on the bottom
I was just thinking maybe the sending unit in the tank had a orfice in it for fuel restriction.Thinking again you might look in the opening of the fuel filter on the 2 sided part and see if you can see a restricting orfice in there.They need a grasping at straws smilie:drool:

Thanks. I'm not sure if they look like this or not. I haven't traced them completely out yet. These 2 drawings will help me trace out the system and see what I got.

 

[IOPort51]

I am wondering if running too much pressure to the carb can change the float position, over time. The fuel is going to go to the path of least resistance. If the float is offering more resistance than the over flow than it will receive no fuel. We are not talking about a large pressure differential.

Hey guys, just to give you a little more information about the fuel filter, I have attached a picture of the fuel filter that I took off the Jeep. I guess this is the one the previous owner had put on. Obviously it's not the stock filter with only 1 inlet and 1 outlet, and it's also rather large. I don't know if you remember some of my earlier posts or not, but the previous owner did not have the vent line connected. Ummmm, maybe he was having the same problem with the stock filter.

 

[dslywalker]

I am wondering if running too much pressure to the carb can change the float position, over time. The fuel is going to go to the path of least resistance. If the float is offering more resistance than the over flow than it will receive no fuel. We are not talking about a large pressure differential.

She was free flowing fuel into the carb with a hose.The FSM says there's a brass filter behind the carb entry point.With it free flowing in IDK

 

[IOPort51]

If the carb offers more resistance than the overflow it goes down the overflow. So you have to increase the resistance on the overflow or decrease the resisttance on the float valve.
I don't think they would have had the overflow if the BBD didn't need it. If fuel starts overflowing from the vent or running out of a seam I guess we will know why.
The difference in resistance could be hardly measurable and it would still bypass the carb.

She was free flowing fuel into the carb with a hose.The FSM says there's a brass filter behind the carb entry point.With it free flowing in IDK

 

[dslywalker]

If the carb offers more resistance than the overflow it goes down the overflow. So you have to increase the resistance on the overflow or decrease the resisttance on the float valve.
I don't think they would have had the overflow if the BBD didn't need it. If fuel starts overflowing from the vent or running out of a seam I guess we will know why.
The difference in resistance could be hardly measurable and it would still bypass the carb.

Gotcha>Would probably still be a good idea to put the B12 in it then like you said.I give up on carbs after the one barrel rochester

 

[RanchGirl]

I am wondering if running too much pressure to the carb can change the float position, over time. The fuel is going to go to the path of least resistance. If the float is offering more resistance than the over flow than it will receive no fuel. We are not talking about a large pressure differential.

Good morning, IO. I didn't get to work on my jeep this weekend to do anymore troubleshooting with the carb. After reading this post, however, I did go out and look at the return line again. I had not noticed this before, but there is a place in the metal return line that has been squeezed kind of flat. It's not completely closed off because when I was cleaning all the gas lines out a couple of weeks ago, carb cleaner did go down the line. It's looks like this restriction in the return line should help force the fuel flow into the carb or could this restriction be causing the problem? If I do need to increase the resistance in the overflow, how would I do that? Squeeze that place in the line a little flatter or is there a valve or something I can install to regulate the return flow? Your thoughts?????

 

[RanchGirl]

Gotcha>Would probably still be a good idea to put the B12 in it then like you said.I give up on carbs after the one barrel rochester

Good morning Sly. As I stated in my reply to IO, I did not get to work on my jeep this weekend, so I have not put the B12 in it yet. I'm going to try the B12 this afternoon, hopefully. I'll let you guys know the results.

 

[IOPort51]

As much fun as it is not, I would follow the fuel line from the fuel pump to the tank and look for leaks. Look for cracked hoses and steel lines and most especially loose clamps. And just for the heck of it pull the dipstick and smell for gasoline in the oil, the sign of a broken diaphragm in the fuel pump. This sounds more and more like the pump is sucking air.
Just for grins you may run a hose from the inlet of the pump to a cup of gasoline and see if it will suck it up and run properly. This will take the fuel line, between the tank and the pump, out of the equation.

 

[RanchGirl]

Great trouble-shooting advice IO. I did install a new fuel pump, but that doesn't mean I got it right. I will do as you suggested and check those things out, especially the fuel lines.

Yesterday afternoon, I did get do a little more trouble-shooting. I just got your post this morning, so I will try those things out today. Yesterday, I was thinking about your comments about the resistance in the carb vs the resistance in the overflow. I went to the Auto Parts Store and ask if they had the checkvalve that shows up in the diagrams that Sly sent me. Of course, they did not. I told them my problem and they suggested that I try a little universal checkvalve they had, that would offer some resistance in the overflow line. I have attached a picture of it. (this is actually a vacuum checkvalve) I pointed this out to the Auto Parts Guy, but he said it would work fine for what I needed. I went home and sprayed the B12 in the carb and let it set as you guys had suggested. I then attached the checkvalve to the top outlet nozzle of the filter (the 1/4" outlet) and then I ran a 1/4" hose from the checkvalve into a bucket. I wanted to see when I started the Jeep how much flow I would have coming through this checkvalve and whether or not the Jeep would run with this configuration. The Jeep did run and I had a small gas flow (probably about a 1/8" stream) coming out of this little checkvalve. Well, I thought, maybe this is good so I connected the outlet of the checkvalve to the return line. Jeep would not run when hooked up to the return line. Once again scratching my head, and then I noticed that when I had the the checkvalve hooked up to the hose going to the bucket, the valve was in more of a horizontal position, but when I hooked it up to the return line, I had a shorter hose and the checkvalve was in more of a vertical position. So, I took the short hose off and ran a longer hose from the outlet of the check to the return line. I also moved the check a little closer to the outlet nozzle of the fuel filter. These 2 changes allowed me to keep the checkvalve in more of a horizontal position like the fuel filter is. Guess what, I start the Jeep and it ran. I let it idle about 15 minutes but it was idling to high (around 1800 rpms). I wanted to back it down somewhat but everytime I got it around 1400 rpms or less, it would go dead. It was also idling a little rough at the lower rpms. Around 1800 rpms, it will stay running on it's own, but that's too high for just idling. The second problem I ran into was that after I let it set and idle for about 15 minutes, I shut it down and it would not restart. Acted like the carb was not getting fuel. I could pour a little gas down the throat of the carb and it started right up and it idled again about 15 minutes. I could rev the engine and it appeared to be getting plenty of gas. Now with all this said, my questions are:
1) Will this little checkvalve work and provide enough resistance for gas flow to go to the carb but also keep the pressure down, so I don't do damage to the carb (if there's not damage already)???
2) Why will it idle at 1800 rpms but not at lower rpms?
3) Why would it not restart? Why did I have to pour a little gas into the carb to get it to restart? After it started it idled fine, just idling too high.

One more little tidbit of info, when I changed my spark plugs and wires, I noticed one of the wires going to the distributor cap was corroded pretty bad (green) and the connection down in the distributor cap looked corroded and rough. I have a new distributor cap and rotor, but I have not installed them yet. Could this be contributing to the rough idling at the lower rpms?

 

[dslywalker]

The check valve probably not gonna improve anything I don't think as most people have probaably removed them if they had them and didn't know it.
I think your idle circuit in the carb is plugged up. IO wil be better on that one. Bad plug wires corrosion all will contribute to missing but it will do it threw out the range of the engine running.Meaning it'll miss no matter what the rpm,faster it goes the more it misses.I think its going to boil down to the carb if check all your fuel lines for leaks or crimps.Let us know how you turn out.