Hey guys whats up. 87 Camaro 305/T5 QuadraJUNK carb. I've had the car for a few months now, and a few times I have ran into some strange sputtering under WOT towards the top of the RPM range, it'll get there and start sputtering as if its missing fuel, I have pulled the codes and I have 32,41,44,53, two linking back to the MAP sensor and one being a lean condition(which is believable), anyway i have already done the tune up, plugs, wires,dist cap, rotor. Ran fine for about a day or so then started to idle a little rough again. Yesterday I almost got stuck when the car started to sputter and run very rough and stalled out a few times, i took the gas cap off and heard a good "woosh" noise as if the gas tank had become pressurized, i'm sure this is part of the fuel starvation problem because i have ran into this problem on a few motorcycles i've worked on with a pinched evap line causing the tank to build pressure and not longer be able to feed the engine. Anyway, i left the gas cap off, this keeps the car running and driveable....BUT....i still am seeming to starve for fuel in the top end it'll sputter real bad the second i reach anything near 4400 rpm in any gear. Another strange thing, if i unplug the ECM power supply line from the battery(you know the black connector) while the car is running, it instantly starts to idle as smooth as a carb'd vehicle can idle....but still sputters in the top end(took it around the block once like this), any ideas?

 

The fuel tank is supposed to be pressurised. It sounds like you're not getting enough fuel to the engine. I'd check your fuel filter. Also, if your carb isn't set up right, you'll run into these problems, especially if you're not getting enough fuel. It may need a rebuild. Also, could be that your fuel pump is getting weak and starting to go bad. Also, which "ECM" power line are you talking about? you need to be a little more specific than "the black connector".

 

Oh come on there can't be THAT many black connectors right? Lol

Anyway id start with the filter like suggested above, and I'm not sure how quadra jets run but could your fp be too weak for it? What did the car have factory tbi or tpi?

 

Sorry for the late response...(over near the batter)the black connector i'm talking about is the power supply for the ECM...unplugging it results in the same as removing the positive battery teminal as far as the ECM is concerned(I assumed you guys would know which i was talking about as it was referenced on this site before)...when it got cold i should mention(we had a cold spurt up here for a few days) the car didn't do this at all, the first warm day the car seemed fine all day except for once when it sputtered under WOT like it has before. Also today it happened a few times....it's less noticeable since i've replaced the tranny mount with a poly model...now the car just loses power where before with the broken tranny mount the car would have convulsions when the sputtering started lol. The quadrajet is the stock carb for this motor(to the best of my knowledge). I thought maybe it was the fuel pump failing but it doesn't seem as such....