Falsus Nomen

OK, 92 LT1, almost 80k miles. Runs great most of the time. The previous owner was a mechanic, and never seemed to figure this one out. He checked the fuel pump, tank and filter, as well as pickup location, but could not find any problems.

With less than 1/2 a tank, it stutters really bad under wot or near wot. As in, snap your head forward, complete loss of power, etc. Not sure why, feels almost like it is out of gas, but as soon as it slows it picks back up again, it will continue to surge and drop until you let off the gas. I want to say fuel pickup is located badly, but I dont know. I would think fuel filter or pump, possibly low voltage on the pump, I know quite a few GM vehicles had problems with wiring for the fuel pump. Also as a note, i put 16 gallons in it when it showed about 1/3 of a tank left, so i think the gauge may be off.

I have driven it about 2000 miles, mostly highway, and have never really had a problem with it. Took it to the track this weekend, had a full tank, and experienced a few problems as well. It seemed like it was hitting fuel cutoff about 5500 revs, well short of 6k, and felt a bit anemic up top. I think its a fuel problem, but I have seen people on here post about cleaning throttle bodies and changing spark plug wires and fixing similar hesitations.

Any ideas? I have searched on here and cannot really come up with an answer.

Linkstar07

I had a similar problem in my 80 Monte carlo with LT1/T56. I, fortunately, had an adjustable fuel pressure regulator and bumped pressure up about 5 psi and the problem completely went away. I'd check the fuel pressure and go from there.

pv34pv3p

My 93 does that jerking/hesitation under WOT only when the reserve light comes on...I was wondering if it was a puter detune or something...

There's a fair amount of tank pressure released when I open the filler, so bumping the pressure a bit makes sense.

rick lambert

May want to check your TPS.

simple green

You seem pretty sure about it being fuel related. Why not put a fuel a pressure gauge on it and see if it's starving at high rpm's.

on another note, I had similar symptoms that ended up being the opti.

good luck

Falsus Nomen

I was thinking about putting a gauge in to check that. I figured I would start with some basics and just make sure everything is ok. I have read a couple posts about plug wires, throttle body, and several other things having an effect on this.

The reason I think it is fuel is because the only way to get the hitching problem is at a 1/2 tank or lower, but it could be something else.

Thanks for the input

engle1147

Had a problem like that (not including the 1/2 empty 1/2 full fuel tank) a few months back problem only showed up a WOT.....on mine it was a bad Fuel Pressure Regulator (FPR).....problem became apparent using a fuel gauge pressure gauge and doing a "bleed down time" test. Changed the FPR and no more problems @ high RPMs.

NEVRL8T

The rev limiter isn't 6000 RPM on an LT1. The rev limiter is just over 5800 so if your tachometer is off by just a little bit then you were probably hitting it.