Hey Guys,
Had the '91 RS out today to take some pictures in the leaves. Ended up having to cut the day short due to what im thinking is mechanical failure. The leadup...

I was stopped at a stop-sign, turning left. I was headed to the gas station because the needle was down around 1/8th. I started to pull into the intersection, realized there was a car coming, and put my foot deeper into the throttle. Car vibrated a bit, and sputtered, like the rear tires had lost traction, and were skipping along the road. I lifted off the gas, and the problem stopped. Gave it a bit of gas again, and the same thing happened. It was now I realized it wasn't a traction problem. Figured the car was being starved for gas after that sharp corner and rapid acceleration, so I coasted to the gas station, a half mile or so away, and fueled up. Started the car, and coasted to the exit, pulled into the street, and put my foot into it again, and it did the same thing...bucked, seemed to lose power, and made a noise I'd be hard pressed to describe...not a metallic, mechanical noise. It almost sounded like that noise brakes make when you're pushing them really hard. If I stayed light on the throttle, I could accelerate, and was able to maintain normal speeds on the drive home. Any sudden, or excessive throttle movement resulted in the same bucking.

I'd like to say that, while I know my way around an engine, my focus to date has largely been on much older engines, like those found on antique tractors. So these guesses are just that. Could this be caused by a vacuum line broken/removed somewhere? Wiring harness, like something off the VSS, fell off? Or does this sound like something more problematic like something within the Trans?

Dont know if this makes a difference, but earlier this year, only a couple thousand kms ago, I switched to Royal Purple Full Synthetic in everything...trans, Diff and engine.

Any help would be great. I need to put the car away for the winter here soon, and its not really drivable the way it is.
Thanks guys!!
AR

 

It sounds like a broken TPS. but if it only happened when low on gas, maybe you should get the pressure checked. thats a start, could be a bad pump. All GM cars cant go below 1/4 without having fuel pump issues.

 

Okay, thats good to know. Thanks! I had a couple people PM me saying that, while they cant explain the noise, they think it might be a clogged fuel filter. I work around old, rusty tractors a lot, and sometimes, condensation forms inside the tank and mixes with the water...or flaky rust off the bottom of an old tank gets sucked into the sediment bowl (1940's fuel filter). I wondered if thats whats happened here.

Is there any way to "check" a TPS, other than replacement? Would running a fuel pump that low have caused damage to the pump...what sort of pumps are these cars running? It did it when low on gas, for the first time, but after I'd put over a half-tank in the car, it did it again. I never tried after that, as I didn't want to risk more damage, so I limped it home and its in my garage right now. Local media is sayin' snow overnight, so I wasn't gonna take any chances.

Anyone else?