90 LeSabre cuts out on highway

Please help.... Yesterday after driving the car for well over 100 miles without trouble it began "cutting out" on the highway. I looked at the gas gauge and I had a little over a 1/4 tank. The car would run decently if I didn't try to accelerate, but when accelerating it would cut out like I wasn't even pressing the accelerator(although it didn't stall, it sputtered and sometimes bucked like it was going to backfire or something). I pulled over as soon as I could and filled the tank, and the car ran fine after that. This has sort of been an ongoing problem, but I usually keep the tank full, assuming that there is a problem in the tank. I just don't understand what it could be if it runs fine when the tank is full and runs horrible(specifically on the highway) when the tank is low.

Thanks in advance for any help with this problem. I love my Buick and want to solve the problem for good(without taking it to a garage if possible).

Also, this is sort of a continuation of a previous post regarding cold starts. The car often will take a while to start or won't start at all when low on gas(1/4 tank or less) if it is cold outside.

Leo
90 LeSabre Limited 3.8L
(sorry for the long post)

Try some drygas product to eliminate water in the fuel.
Condensation occurs in the gas tank in cold weather. Water is heavier than gas so it accumulates on the bottom of the tank. When you run the tank low, you suck up a percentage of water with the fuel causing misfires.

"cutting out" on the highway. 90 LeSabre Limited 3.8L

I have found a gas cap can do that .. the tank pulls a vaccuum and well you get the picture.. .

At least you can eliminate it somehow by loosing the cap for a drive or two...


Bassasasom

It might be that the fuel pump isn't seated properly. Put a pressure guage on the gas line when it does it, and see if the pressure is where it should be (around 38lbs) or low/fluctuating.

I would almost say your fuel gauge is inaccurate and it's out of gas from the way it sounds. Should keep over 1/2 tank tho, pump is cooled and lubed by sitting in the fuel.

I've been running drygas almost all winter, and I know it can't hurt but I'm not sure if that's the problem. My fuel gauge is definately inaccurate...When I said it was around a 1/4 tank full, it actually read 1/2 tank, but after the last post I'm thinking that when it shows a half tank it could possibly be empty, rather than being empty at a 1/4 tank as I previously assumed. Any thoughts on this? How many gallons should my tank hold? I definately need to get my fuel pressure checked. I guess I'm gonna have to break down and buy a gauge pretty soon. But I first have to replace my windshield before my inspection is due :disappoin . Thanks again for all the help so far.

Leo
90 LeSabre Limited

It probably holds about 18 gallons if empty. I guess the fuel filter is okay? Every time I have had an electric fuel pump fail, they just die and never come back. I have had my fuel pump and sending unit out of my 97 Buick. Seems like it has a little screen on the bottom of the sump rod where it pulls the gas. Maybe when it gets low, it can't pull the gas through it because there is some sediment or something in there.

Well, on my '87 PA the guage was always a little twitchy on the lower side (would bounce alot) before replacing my pump. When I replaced my pump, the opening is rather tight and I know I hit the float arm against the ring of the tank and now it does about the same as yours when I get down to about 1/4 tank. Kind of just freezes there until it feels like registering. But given it's a PITA to get that sucker out again I jsut live with it when I get that low.

Tank is an 18 gal BTW.

I have seen faulty gas gauge readings in other cars. The gas gauge would work normal until it read 1/4 tank where it stuck at and wouldn't go any lower even when the tank was run dry. It meant the float on the sending unit in the tank is stuck.

This would be a seperate problem from the usual problem with GM gas gauges of periodically "floating" up or down and settling back to a true reading.

Does it still do it with a full tank? I ask because i had a 95 lesabre that did this exact same thing but only when the tank got low. Turned out there was a cracked plastic deal inside the gas tank that looked similar to a cut off bottom half of a 1 gallon milk jug. It was called some kind of resevoir. Had to buy a whole new tank since that part didn't come seperate...

When I had my gauge sending unit out of the tank on my '97, I could see a plastic box-like housing deal inside the tank. It looked like something that couldn't be removed without tearing the tank apart. The sending unit kind of went down in the middle of it. I figured it was some kind of baffle or housing that would prevent readings from abruptly going up and down. Although, the reading from the tank goes through the computer for the 97. The signal is buffered, to some degree, to account (adjust gauge readings) for the shape of the tank and slosh.

When I had my gauge sending unit out of the tank on my '97, I could see a plastic box-like housing deal inside the tank. It looked like something that couldn't be removed without tearing the tank apart. The sending unit kind of went down in the middle of it. I figured it was some kind of baffle or housing that would prevent readings from abruptly going up and down. Although, the reading from the tank goes through the computer for the 97. The signal is buffered, to some degree, to account (adjust gauge readings) for the shape of the tank and slosh.

This was years ago so I forget what the mechanic said but that plastic thing has to hold a certian portion of gas for some reason or another. Mines was cracked so it didn't hold the right amount. You didn't notice it with a full tank but you sure did when it got toward empty.

I believe the theory behind the design did a few things, anti slosh, act as a pump resevour (s/p) for the forementioned pump lube & cooling, and since it's white, it makes spotting tank debris easier.

It must kind of hold the gas in place when cornering and going up and down hills to some degree. I don't understand how it could make it run poorly though. It seems like when your cruising down the road, the gas level in the tank is going to be even or level, regardless of the plastic piece, presuming gas flows in and out of it. It should all even out.

Another update...I got down to the half tank mark on the gas gauge again the other day on the highway and it did the same exact thing, it cut out and then sputtered a little before running decent for a bit, and then repeating the same cycle. It seems to be get worse the more I accelerate. After filling the tank(it took just under 11 gallons to fill from the half tank mark) it ran beautifully. Normally I try to keep the tank as close to full as possible, to eliminate the problem, but I've been trying to figure this out. Drygas definately is not helping though. Thanks to everyone who has replied so far. :smile:

Leo
90 LeSabre Limited

Another update...I got down to the half tank mark on the gas gauge again the other day on the highway and it did the same exact thing, it cut out and then sputtered a little before running decent for a bit, and then repeating the same cycle. It seems to be get worse the more I accelerate. After filling the tank(it took just under 11 gallons to fill from the half tank mark) it ran beautifully. Normally I try to keep the tank as close to full as possible, to eliminate the problem, but I've been trying to figure this out. Drygas definately is not helping though. Thanks to everyone who has replied so far. :smile:

Leo
90 LeSabre Limited

Man, that sure sound familiar. Thats exactly what mines was doing. I started to fill the tank and sell the car but I liked the car...

I have a problem similar to yours but mine doesn't cut out, my gas guage will go up to 1/4 tank then it won't get any "fuller" but it will lower, i just never have let it get to e to find out if its really empty ;)