Carb hesitation

The problem continues! The hesitation is diffenetly better. Now it wants to die on me when Im out Jeepin around in the blm. Then it wont want to start for me. Ill crank on it and crank on it, then it well take off but very slowly. Then you rev it up and let it come back down to idle and it might or might not idle. Its almost left me stranded a couple of times now. So the things I have done are , rebuilt the carb, replace the points, cap, wires, plugs, coil, ballast resistor, and cleaned out the tank and tried bigger jets. Im almost to the point of sending this thing down the road. It has been nothing but a piece since day one! Not only that, but parts are super hard to get at the local parts stores. Ive never had this much trouble with any of my rigs. This Jeep makes my samurai look better every day and the samurai is a gutless wonder, at least it runs good and is dependable. This wanting to leave me stranded places is not going over well.

 

I am not very familiar with the V6 and have not worked on many 2G's. I was wondering if your model is new enough to have a charcoal fuel vapor canister on it with a vapor line to the float bowl.

If this was a YF that would start but not idle or idle very poorly ( assuming diaphragm is good ) I would be looking to see if there is any tiny rust particles in the idle jet tube orfice.

I have traced rough idling, stalling at idle and harder than usual starting on some waggys with the MC2100 to tiny pieces of charcoal from the vapor canister lodged in the bottom of the idle jet / pickup tube, when the canisters get old bits of charcoal can work their way into the float bowl. An inline fuel filter installed between the canister and fuel bowl will cure this.

Just a thought, I dont know how your rig is equiped emmission control wise.

 

Thanks for the ideas. I dont have any emissions stuff though. Ill Jeep it tomorrow and see if the changes I made tonight well have made any difference.

 

More food for thought, Its possible you have a fuel filter you dont know about contributing to the problem. PO could have put a filter between pump and tank if the jeep sat and got some rust in the tank.

This works fine if they are kept changed real regular because it does not take much to restrict the suction side.

 

Thats a good point! Ill look for that when I get a chance. I took it out today and wheeled it all day, not hard but all 2 track roads. It seems to be running alot better without any hesitation at all. Maybe the coil had something to do with it? I got horrible fuel mileage though. It was full this morning and I ran it all day for the most part and rolled in to town with about 2 gallons to spare, according to the pump. I think I must have put maybe 50 or 60 miles on it. I dont know what they are supposed to get, but thats horrible! I havent pulled a plug to see if its running rich or not. I did put in a little bigger jet. Its running pretty good though right now I dont want to screw it up again.............Watch, tomorrow it wont even start!

 

Have you checked the compression, with either a compression or leak down test? If you have poor compression you can't ever expect a good, smooth running engine. Just my .02.

 

I need to do that. I also have been doing some research on fuel mileage and it says that normal vacuum is around 20", Im running about 15". Also people are saying they are running their idle screws out about 1 1/2 turns, Im more like three turns out on the idle screws. Could this be because of the jet size being to big?

 

Thats it! Im selling it! Just another problem to try and trace. I live around 3000 feet.

 

Is there a possibility your carb kit came with the wrong base gaskets? The needle adjust having to be out 3 turns tells me you have something wrong below the throttle plate (vacuum leak). I had a wrong gasket in my last rebuild kit.

 

Well it came with three gaskets. I originally used the correct one, it lined up with the carb ports and everythingand looked like it had the correct cutouts. Then I had to take the carb off and that gasket ripped. So I used the second gasket that came in the kit. This gasket is about quater inch thick and covered up two holes coming out of the intake. Theres a passage way built into the carbs that allows these holes to be connected to each other. They have a lot of black soot in them so Im not sure what the do, but it loos like they come from the exhaust. Maybe I need to get the correct gasket again? Also Im not sure if the jets I put back in there are to big? Finally I dont think I have any vacuum leaks, I have searched and searched with starting fluid and havent found anything, inless there is a enternal leak.

 

The 2G has a power valve in the bottom of the float bowl that should allow more fuel on acceleration. If that channel is plugged, you'll run lean, but I don't think it would affect plug color since it only operates for a short time. You might want to check it though. Is one of your main jets plugged up?

 

Well I swapped in the smaller jets tonight and it ran like crap. No power off the line and wanting to die on me. Im giving up Im afraid. If I put the bigger jets back in, Ill go back to around 10 mpg and thats not tolerable. I can usually fix things, but Ive reached my limit.

 

With the plugs nearly white, running the idle mixture screws three turns out means that you are running lean and that a main jet or jet passage is blocked. The idle screws are gas mixture screws, not air screws so if you have them that far out to make it idle then they must be partially blocked to or timing is off. The exhaust does run through a set of passages under the carb. That warms the carb quicker so you don't need the choke so on long. When are you measuring 15in. of vacuum? I believe that with a 2G you would have 0 in. of vacuum at idle since the vacuum port is below the butterfly, it doesn't see vacuum till the butterflys are partially open. If you have vac. at idle then the butterflys must be open and they shouldn't be...except for a tiny bit. Therefore it sounds like the timing is too retarded and to get idle sped you have to have the throttle opened. Retarded timing will make for low power and so you have to have you foot in it to make it go meaning bad mileage, but 12 to 14 mpg is what must folks get I think.

 

Thats a great explanation. On my carb I believe the vacuum port is above the butterflys. Im measuring the vacuum at idle.

 

Sorry to disagree with you Pat but the 2G in fact has a power valve too. Holleys work a little differently but both send more fuel to the venturi--> manifold--> engine. The 2G's power valve is in the bottom of the float bowl.

 

Ok so you got me doubting myself so I got into my books and let my experience go by the wayside. 2g, 2h and 2GV's all have power valves accuated by the power piston which is activated by low vacuum. With the same carbs, idle screws are fuel jets, not air jets. Air jets are on motorcycles using Mikunis, Kehiens, and used to be Amals. Automobiles use fuel jets. The manifold vacuum is or can be measured below the butterflys, but my 2G has 0 in. of mercury at idle and it is a horizontal slit below the butterflys. At just above idle, the butterflys crack open and vacuum rises.

 

Ok, lets start at the top. Fuel is not stored in the base plate but it passes through it for idle mixture. The power valve is an actual tapered valve activated by low manifold vacuum. It is not the accelerator pump. It dumps additional fuel into the venturies when you mash the accelerator. Same as Holley but uses a rod the open the valve rather than exposing it's power valve to pure vacuum as in the Holley. I have attached drawings from the Rochester Carb. Book. Meanwhile, back at the ranch, this fellow still has hesitation problems with his jeep.