Carbureter Woes

I have a 1984 XJ with the 2.5l engine and the single barrel carb. My vehicle is stalling everytime I come to a stop. It starts back up every time and drives fine.

I have gleaned from reading a few threads that the best cure appears to be a Weber, but I'm a few months away from that.

Being computer controlled I am hesitant to say time for a re-build but I am open to that possibility.

Do any of the sensors/vacuum switches effect the vehicle idle coming from a open throttle state?

Thanks

Rob

argalaviz said:

I have a 1984 XJ with the 2.5l engine and the single barrel carb. My vehicle is stalling everytime I come to a stop. It starts back up every time and drives fine.

I have gleaned from reading a few threads that the best cure appears to be a Weber, but I'm a few months away from that.

Being computer controlled I am hesitant to say time for a re-build but I am open to that possibility.

Do any of the sensors/vacuum switches effect the vehicle idle coming from a open throttle state?

Thanks

Rob

Click to expand...

Just about every sensor/vacuum switch EGR PCV Plug's air filter. Did you try a tuneup?

The single biggest failure problem on the Carter YFA carb is the automatic choke. It fails due to loosing its ground connection. Once the engine starts, it will suck the choke plate open and everything will run pretty much OK, but it will sometimes hard start when warm and run rich. The problem is that the ground exits out from under the plastic cap and should touch the hold down ring. That connection corrodes or simply gets bent so it doesn't touch. I take a piece of wire and solder it to the ground and then run it down and put a crimp lug that fits around the carb hold down bolt. A quick way to verify this is the problem is to get a bread twist tie and to wire the choke plate in the open position and verify the problem goes away.

Good Luck.

Ah - why not get PCM and fuel injection from a later donor and get rid of the carb entirely? You should pick up a little power, a couple miles to the gallon, and less problems when "off-camber."

You'd need the intake, fuel setup, fuel tank (probably,) and support electronics. It would take a while, but the mod should pay for itself - and a little quicker than usual, at to-day's fuel prices.

I do suggest using new sensors and injector(s) - but that's largely up to you.

5-90

I have read a few threads on the injection swap and I believe it involves bell housing too. This is my daily driver as well as play toy...

I'll check the choke, and double check vacuum.

Thanks you

Forgot about that - crankshaft sensor. Still, something to ponder...

5-90

I did the carb to TBI swap and it makes a ton of difference, along with considerably better mileage. Yes the bellhousing needs to be swapped along with the flywheel or flex plate. I found a donor at the junk yard and scored everything for $100. The hardest part was patching the wiring harness. I recommend grabbing the whole dash as well. Then the wiring gets much easier.

You guys are tempting me...

When I aquire a commuter and can have my baby out of commission for a few weeks I may just tackle that issue. The threads on the hows and whats of the swap are pretty good.

I love this little engined Jeep. I am running 32's and can with some planning exceed the 70 MPH speed limit on I-5. It does great on the trail.

If I buy a wrecked 2.5 wouldn't make sense to just swap the engine, tranny and tranfer case? I if I'm replacing the harness anyways why not.

Thank you again guys.

old_man said:

The single biggest failure problem on the Carter YFA carb is the automatic choke. It fails due to loosing its ground connection. Once the engine starts, it will suck the choke plate open and everything will run pretty much OK, but it will sometimes hard start when warm and run rich. The problem is that the ground exits out from under the plastic cap and should touch the hold down ring. That connection corrodes or simply gets bent so it doesn't touch. I take a piece of wire and solder it to the ground and then run it down and put a crimp lug that fits around the carb hold down bolt. A quick way to verify this is the problem is to get a bread twist tie and to wire the choke plate in the open position and verify the problem goes away.

Good Luck.

Click to expand...

Well, I ziptied the choke open and had no improvement. I thought for sure this was going to be it.

Time to check vacuum again.

Re: Carburetor Woes

Autozone has a remanufactured carb for $175. This I can do today, there is no core charge so I can theoretically have my old carb rebuilt as a spare. I realize injection or a Weber are more desirable options, but when it was working the carb was adequate for my needs.

I do have few more questions however.

Idle stop solenoid, I attempted to adjust mine and there was zero change in the idle speed. If this part has failed is it normal that while driving the carb works acceptably? Or should this solenoid pretty much disable the functionality of the carb if not working?

My thinking, and I qualify this statement with the addmission that this is my first carburetor equiped vehicle since the late 80's so I could be way off, is that I replace this solenoid and my carb works as well as it can and my life is great. Plus it's only $35. So I'm saving money for more exciting stuff like more wire to finish welding my rock rails up...

Thank you

Rob

Re: Carburetor Woes

I'm not sure what you mean by "idle stop solenoid". Are you referring to what on the Carter is, I believe, generally called the "sole-vac"? (The Rochester 2 bbl. has an "idle stop solenoid".) The sole-vac increases the idle speed under various conditions, most importantly in this part of the country, when the A/C is activated. I am not sure offhand if this also serves to ease back to idle when decelerating but mine failed some time before I replaced my Carter (85 2.5L XJ) with a Weber in January and I had no idle problems other than the aforementioned A/C. I don't believe that the sole-vac has any funtion other than idle speed adjustment.

As a side note, the Weber does not come with the equivalent of the sole-vac and it is the responsibility of the new proud owner of the unit to cobble up some kind of bracket to mount a solenoid. Anybody done this? The Weber is a beautiful machine compared to the ancient YFA but I agree that the latter when properly functioning is quite adequate. The most important immediate gain for me with the Weber is an increase in mid-range torque but other things have intervened and I'm not sure I have it adjusted to its full potential. That said there is no way you can argue with ultimately converting to TBI.

I assume that time is a problem for you right now but will mention that the Carter is a really simple machine if you do have time for a rebuild -- I rebuilt mine several years ago with no previous carburetor experience. Took about a day plus an overnight soak and to my amazement it worked perfectly for about five years and was still okay for day to day drivability when I replaced it.

I'm an ID10T!

My carb was falling apart. After tightening everything up it runs good.

Thank you for all the good advise.

I am going to begin aquiring the parts to swap over to the newer injection.

You're not an idiot. You found the problem without any prompting. I was just going to comment that those old carbs tend to have the screws holding the upper part of the body to the lower vibrate loose, but then I saw you found it all by yourself. Well done -- I had to have someone tell me.

I was just about to post "tighten the carb" (same goes with all AMC carbs except the 2100/2150) when I saw you figured it out. You can also swap the harmonic balancer for a CPS version (they are also made for 6 cyl HO conversions) or make your own with the 6 cyl bracket and drill the correct holes in a spare one. I picked up a '95 YJ2.5L with the whole system I was going to put into my '84 2dr, but since I'm getting ready to move, I'm selling the works to a friend of mine in need of a running project. (I know she'll make it run again)
I'm in the process now of converting a carbed 4.2L '84 Jeep J10 into a "monster truck" with 4.0L (4.6L waiting to assemble and install later on propane) AW4 from a '93 Grand Cherokee (harness and all once I figure it out)and NV241 Rock Lock from an '03 Rubicon (or brand new from http://jbconversions.com )