What is going on with my 1990 Buick Century?

Question

My Buick Century (3.3L engine) has 178k miles and has always run great for the last 3 years I've had it but now I'm coming up with a problem. About 6 months ago it started stalling out randomly. It would stall out off and on for a few days, and then run great for a few weeks or more. Then it would start stalling out again, stop after a day or two and the cycle still continues. Sometimes it runs great for about 2 months or so.
Ran into some trouble with the cooling system and my dad went to replace the thermostat but whoops - forgot to actually put the new thermostat in. So, my Buick (after I was assured it would be fine since it's summertime) is now running without a thermostat.
A few weeks ago (about 2 weeks after the thermostat incident), its Service Engine Soon light started coming on. This little light is giving us more stalling out at random points during our commute and occasional case of 3 second shaking as we let off of the gas perhaps a few times a day. It runs louder, almost as if it wants to rev higher?
But the kicker for me is, it does not happen all the time. Sometimes there's no noise but it still shakes, it hasn't stalled out for over a week now, and lately the light has been actually staying off for a few trips and then going back on. During the time that the light is off, my car will run flawlessly. Sometimes the light will go on and off during a commute too.

I really have no clue what is going on with it. I'm thinking it's something to do with the fuel filter but I'm not sure... it does seem to run better when it's not too low on gas. Also, could this have to do with it's lack-of-thermostat?
Any helps appreciated. Can't afford to take it to the garage until payday, unfortunately.

Answer 1

It is possible that you have a bad CKP (crankshaft position sensor) as these have a high failure rate on these vehicles and have a stalling problem as you describe!

Answer 2

1990 Buick Century Problems

Answer 3

I don't think it's related to the thermostat. But without a thermostat, the computer thinks the car is running cold all the time and you are running with a richer mixture. A cold engine doesn't run as well as a warm engine. Fuel doesn't vaporize as easily either.



The engine may be running in default mode due to some problem relating to the SEL light. Have the SEL codes read. See if there's a stored code that might be related to your stalling problem.



I would be looking for a fuel delivery problem, very possibly the fuel filter. Without knowing more, that's all I can offer.

Answer 4

if your check engine light is on that means that there is something wrong and that you can find out by taking your car to a repair shop and connecting it to a computer. with the 1990 Buick it should have OBD 1 (on board diagnostics) it is a very easy system to read. I would do a little research on this system, or have your dad do it and you should be able to "jump" the computer in the car, and it will give you a code by flashing the check engine light in a certain sequence. you can then look up that code, and figure out what is wrong. This only works with the OBD 1. different cars have different codes.

Answer 5

A lot of your senors are Temperature controlled, that regulate fuel settings and other things, so not having a thermostat could cause problems, your engine needs to be kept between different heat operating ranges, that is why engines have a thermostat, good luck.

Answer 6

WOW, All of that being said, it's a simple problem, simple question, simple resolution.



Put the proper thermostat in and make sure it's right side up.

Replace your fuel filter.



The car isn't running at the correct operating temperature and it's also starving for gas.

Answer 7

A 1990 Buick takes R-12 refrigerant which isn't offered to customers. you like a license to purchase it. except the motor vehicle has been switched over over to R-134a refrigerant. if so, you need to purchase that at any motor vehicle areas shop.

Answer 8

check out the ignition switch