Stumble off idle MC 2150

Stumble off idle MC 2100

I purchased a '78 cj5 with a 304 and MC 2150 a couple of weeks ago. When I first got it the fuel pump diaphram was bad and no gas to carb. After I fixed that, I noticed off idle hesitancy when driving. I noticed gobs of fuel on the manifold. Replaced the accelerator pump diaphram. Fixed the fuel on the manifold problem and it shoots fuel when you hit the gas pedal, but it still has the hesitancy off idle and if I really push the pedal down it backfires through the carb. After doing some reading Timgr states that the power valve may be bad. What do you all think?

Thanks
Ryan

 

my experience has been a bad power valve doesn't cause backfiring, just sluggish response and very poor mileage.
It's easy enough to check, shouldn't be any fuel on/in the cover when you remove the cover.
The backfiring could be multiple things: bad plug wire, out of time or tune.
The hesitation could be multiple: acc pump adjustment, EGR valve opening too soon (there should be a delay valve in the line), or numerous other small problems.
Does the Jeep still have all the emissions equipment installed ?

 

Check timing. Back firing through the carb is combustion on the wrong cycle.

 

Yes it still has all of the smog equipment. It passed with flying colors too. It looks like I have several things to track down. Any feedback is greatly appreciated.
Ryan

 

I think a 2150 has an external vacuum hose to the power valve. If you pull it off, and gas comes out, it's busted. However, I'm sure you would not have passed if the power valve were busted.

You might try richening the idle mixture a little. You can also adjust the accelerator pump shot to give more fuel by changing the hole that the rod goes in on the throttle arm or pump arm. Moving in on the pump end or out on the throttle end will increase the pump shot. Another possibility is to richen the high-speed mixture by raising the float level.

 

Thanks for the tips. I will give those a try first before I make any major changes. I will also check condition of plugs and timing to boot.

 

Problem solved!R) It turns out the timing was set at 0 DBtdc. I can't belived the smog guy didn't catch that one? Thanks for the help everyone.