old carb: Carter BBD
new carb: Motorcraft 2100 Purchased as a kit from Ebay (Mike Ehrmann)
I wanted to get rid of my Carter carb. because of cold start problems and incline/decline stales while offroad.
Anyway, I did some reading and research and decided to purchase the Motorcraft 2100 kit (includes adapter plate, accelerator linkage, and manual choke) from Ebay.
I followed the comprehensive instructions supplied by Mr. Ehrmann on the CD that was sent to me, but have ran into some problems. I sent Mr. Ehrmann some pictures of my set up, which he promptly replied to with some suggestions. I followed his suggestions, but still the problem exists. I emailed him again two days ago, but he has not responded yet. I HAVE ONE WEEK TO GET THIS JEEP UP AND RUNNING!
The engine idles fine, great acceleration, but cruising at mid-range the engine pulsates (it does not hold a constant speed) and feels jerky. I also get a lot of exhaust popping under deceleration and at idle. I can actually hear the popping in the exhaust manifold.
Things I have checked:
1. Sprayed propane and brake cleaner all over the carb. and there is no evidence of any vacuum leaks.
2. Plugged the EGR valve (vacuum operated).
3. All bolts/nuts are tight on the carb to adapter plate and adapter plate to the intake manifold. All surfaces were prepped prior to installing the adapter and carb. gaskets.
4. Manual choke properly installed and working fine.
5. Checked the charcoal canister and my four lines are hooked up right.
6. I played with the fuel mixture screws a quarter turn at a time. I used a range of 1.5 to 4 full turns out on both screws. I found the optimal setting was about 2.75 turns out on both screws. The engine idles fine, great acceleration, but cruising at mid-range the engine pulsates (it does not hold a constant speed) and feels jerky. I also get a lot of exhaust popping under deceleration and idle. Now the motor runs extremely rich.
I thought about checking the distributor points and spark plugs, but they were just fine hours prior to installing the Motorcraft 2100 carb. I did not touch them during the new carb. install. So, I have not checked them. I did not see the point in doing that.
Any help from you guys would be greatly appreciated.
The problem is only at cruise.... I am going to guess power valve.....
With a vacuum gauge... get a reading on your hwy cruise vac level.... the power valve should be set 2" HG vacuum below that level. So when you touch the gas the power valve opens up and helps with the extra fuel..... If this is too close it will always come on, not supply extra fuel when you need it, and will make you very rich at cruise. From what you say so far that would be my guess.
Try to get your hwy cruise vac level with a gauge and long hose so you can see the readings in the cab. Call you carb guy back with this new info and see what they set the power valve at on his rebuilt carbs. You may need to change the power valve setting vac level.
I can't help with the problem, but I'll second (again) the vote about communication problems with Mr. Ehrmann. It does force you to actually learn something about carburetors, though - enough to make you regret buying from him instead of scooping one off of eBay and rebuilding it.
It does make me glad I've got aftermarket intake/exhaust manifolds, though, seeing the mess above and knowing I have a grand total of four hoses in my engine: fuel in, vapor out, vacuum advance out and PCV in. With the manual carb, it's basically idiot-proof, which means I still have occasional problems!
I bought the setup from the same guy too. The first carb I got was so messed up it wouldn't respond to anything. I ended paying a good ole boy ( carb expert) to go through it and he just shook his head with the crap he found. So I had another carb sent to me, only to find it had problems as well. Long story short, Mr Ehrmann quit responding and blocked me from making any comments on his web site. Cause I was gonna say plenty. So only recently I'm getting a similar problem with cutting out in top gear. Kinda like the ignition is getting turned off and back on. Idles fine and no problems on acceleration in the first 3 gears. I might have an ignition problem, but my buddy "dslywalker" sent this thread to me a long with many other good ideas to help troubleshoot my issue.
I have a question , on top of the carb in front of the air cleaner you have a plug on the fuel bowl vent, IS this right ?? shouldnt that vent to the charcoal canister ??? Also could this be causing any problem when running ??
I'm not a carb eggspert I only know enough to get myself in trouble sometimes so there should be some guys with knowledge of this wether its OK to just plug it or if it could cause an issue. I'm wondering what the answer is. ???
It seems to be fine for me, but cant explain the intermittent problem I'm experiencing. Great acceleration and all. Just when I'm at cruising speed. I'll hit the wiring this weekend and see what I find. The carbs are good!
I got one from him and it worked pretty good. I had to play with the accelerator pump linkage a bit to get it to accelerate strong. About a year after buying it I lost the linkage keeper for the accelerator pump and emailed him, he responded and sent me two free of charge. Sucks to hear you guys had bad experiences with him. My install went real easy, I didn't even see the CD he included with the instructions untill after I got it running and was chucking the box into the garbage. It does sound like a exhaust leak, maybe at the manifold. Is the idle good? maybe a combo exhaust/intake leak from loose manifold bolts. Is it a full exhaust all the way to the back bumper? Mine ran like crap and popped with a flowmaster and a turn down in front of the rear axle. put a tailpipe on and it was much better and sounded better too. Good luck.
One thing I see is that you are using the thin gasket between the carb and adapter. When I used that gasket, it ran like crap. Took a while to isolate it as it appeared to have no vac leaks. There is a much thicker gasket you can get at any auto parts store for about 5.00 and seals much butter!
I would set the timing and then use a vac gauge to adjust mixture screws to achieve highest steady-state manifold vac at idle as a starting point.
I would also connect the capped carb vent over to the correct port on the charcoal canister.
Hey, wait a minute... I thought the MC2100 was supposed to fix all the problems with a 258!
It does.......unless you buy it from the ebay guy it seems!
'84 CJ-7: Yota axles (spartan locked front, e-locked rear) 4" BDS, 1" Daystar & 3/8" shackle lifts, 35" X-Terrains on steelies, YJ Tub & family roll bar, heater blower upgrade, 4.2L w/MC2100 & Team Rush, Warn 8274. Rebuilt 4.2/4.0 hybrid, AX15 and twin sticks/clocking ring waiting to go in.
The advertised position for a topless, dirty jeep girl has been filled......by my wife. Thanks to all that applied.
<------------and yes, that is her. :-D
Mr Ehrmann has not returned my last two emails. I ended up taking the carb to my local carb shop. The shop charged me $135 to un-f*&k what Mr. Ehrmann did. The jets were too lean and I had asked Mr. Erhmann to give me jets for 1200' elevation. The jets in the carb measured .047" and the shop had to drill them out to .053". Also, the carb was not very clean internally and the shop had to blow out the carb with solvent to get a lot of the crud out. Mr. Ehrmann gets a big "thumbs down" for me.