Alright, not too long ago I put a bottle of fuel system treatment in the car, at the same time as I changed the oil over to full synthetic. A day or so later, the car started running really badly.

Starting and idling are fine, but when I put it in gear and get up to 1000-1500 rpm, it starts to "stumble" really bad, for lack of a better term. It's mostly when upshifting to second gear that it happens. The entire car starts to jerk, like it's getting fuel, then not, then getting it again, then not. When it happens, I press on the gas, and it stumbles maybe once more, then takes off and runs fine. I don't think it's a transmission problem, because it happened today, sitting in the parking lot at work with the car in park.

It also did it around 3000 rpm for a day or so. I'd be accelerating, and the rpms would "hang" right around 3000 for a second or two, and then it would take off again. The problems are more pronounced when the car is cold, as well.

The reason I'm thinking it's something with the fuel pump is because a day or so after all this started, I noticed that I wasn't hearing the fuel pump anymore from the back end of the car. I've read in a couple other posts that a whining sound is indicative of a bad fuel pump, and with what's going on now, I'm wondering if that's what it is. I plan on checking it over a little more thoroughly tonight, and possibly replacing the fuel filter on the chance that it's clogged.

So does it sound like the pump's shot?

Thanks in advance.

(By the way, the car is a 305 TPI, auto trans with ~97K miles.)

 

86,

The easiest (and surest) way to determine if the pump is good is with a fuel pressure test. Connect your gauge to the Schrader valve and find out.

 

Maybe you stir'd up some nastys in the tank with the cleaner and plugged your filter ?