Stalls when gas is pressed

[curious10ne]

I recently became the owner of an 88 YJ. Having fun with my first vehicle, but she has problems. When she's cold, especially when it's cold out, for about the first half hour of driving she'll bog down and sometimes stall when I press the gas. After that things are OK, but for that first 30-45 minutes it as if it's constantly flooding. If I'm careful and feather the gas, she'll take off normally. But if I just press the gas, she'll stall every time. She doesn't stall during braking, only when I press the gas to take off. She also seems to be really hard on gas. I worked it out, and I think I'm getting about 7 MPG.

The engine is a 4.2L with an automatic transmission. While I don't know what type of carb is in it, the previous owner told me he put a new hill-climbing carb in it. Wires and spark plugs are new. Checked to make sure the chock works. Starting from cold is no problem...2 pumps on full chock and it starts right away. Idle seems to be OK, about 1200 in park and 700-800 in drive. I generally let her warm up for 10-15 minutes, or until the defrost is blowing relatively warm. There is a problem with the transmission slipping for the for 30 minutes driving as well, which could be related. I'll take her into a mechanic, but I thought I'd check to see if there was any relatively simple things to look at first.

 

[ka041a]

sounds like a vacuum leak to me.grab the carburetor and twist and wiggle it to see if it is loose from the manifold. also there should be a short piece of rubber hose at both ends of the steel tube that connects the vacuum modulator on the transmission to manifold vacuum on the engine which could be rotten and leaking, that would also cause the transmission to have trouble upshifting.a vacuum guage is a very handy tool that can help diagnose a lot of problems. john