Why is my 1990 Buick w/3.3 cutting out after filling up?


Asked by Apr 17, 2016 at 09:12 AM about the 1990 Buick Century Custom

Question type: Maintenance & Repair

This just started a couple of months ago, but seems it is getting a little worse.
I always fill up at 1/2 tank but now when I fill up car crank fine, takes off fine, speeds up fine, then about 2 mile up the highway it starts cutting out like it running out of gas. Usually after a couple of more miles it will stop cutting out. I could put it in neutral, rev motor up it doers not cut out, then back in drive it does until that 2 to 3 more miles,
I have also noticed it may or may not do it again a time or two UNTIL it gets below 3/4 tank then it does not do it again until I fill up again.
Also last week or so if it does it and I am pulling in at home or somewhere it may die, but starts right back running ok.
First thought of water or trash in system but have tried a cuple of rounds of Seafoam with no help from it.
But then I wonder why does it only do it between 3/4 and full tank of gas?
When it's not cutting out below 3/4 tank I have tried rocking the car by swerving side to side to shake the gas up to see if would start...nope, only over 3/4 tank.
Oh less than a year go had new fuel pump, fuel filters, and new injectors put it and has been running fine.
Could it be a venting problem in the gas cap, tank, or somewhere?
Somebody please tell me what I'm missing.

8 Answers


Oh, also not getting any bad codes on my Buick.


it sounds like a bad purge valve. if the evap system cant purge the fumes it will run rich and do weird things. wouldn't hurt to scan for codes anyway. easy with a paper clip. search "how to scan GM OBD1 codes ", lots of youtube vids.

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I was also thinking along the line of the tank vent system. Any chance the tank vent is pulling raw gas in and making it run rich? Might test that by unplugging the vent to the tank at the canister.

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I have thought of those answer. Just not familiar with evap and/or venting systems. Never had or dealt with a problem with those. I did pull codes with the old paper clip trick, only got the 12 code. Is the canister on 90 Buick under hood on passenger side?

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Oh, Thanks for the quick response guys. I tried this on another site with another problem before and NEVER got any answer or guess from anybody. Again, Thanks


I would suggest getting a Haynes or Chilton manual for the old girl. Should give you what you need for info on the evap system for that car. I have a 90 Lumina and the book helps a lot. Sometimes its hard to find a part location for the older vehicles online.

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Best Answer

Hey guys, I'm back. Schedule & weather has kept me from doing much lately but hopefully this weekend I am going to give my little Buick the once over. Going to check wire harnesses, connectors, volts to sensors, ohms, control wires/voltages, as well as clean MAF, TPS, & IAC Valve. Got some MAF cleaner, throttle cleaner, & stuff as well as gaskets for all. Looking for any more opinions to maybe help confirm or discount my suspicions. Ok, I have ruled out the evap system, no raw gas, lines open, did compressed air test, power to system, solenoid ohms ok, unplugged it's terminal, drove a while and got trouble code, ect... New data, symptoms have changed &/or worsened. Things I have paid more attention to (A) Is that now it could happen at any time within 5 mins of driving car to 20 mins. Must have been in early stages at first post. (B) First noticed that it was as I was getting off ramp to home & work when letting off accelerator. Got to playing with it & it usually happens when making speed adjustments with accelerator when slowing down (letting off accelerator) or a lot of stopping & starting at traffic devices or just adjusting to traffic. It may or may not stop while going on. (C) When getting really slow at driveway &/or backing in is really rough. Just once it went dead & did like a big gasp for air & usually spits back out of throttle duct when stays running. (D) Most of the time when it dies pulling in, I put it in park, turn key off, then back on to crank & it will run good for a couple a mins. SOooooo, I tried something. Got speed up (when acting up) put in neutral, killed engine for 10 or so seconds, cranked back up and 2 out of 3 times run good til letting off throttle. Like it was resetting something. (E) once when it was idling rough after getting home, I starting tinkering, unplugged IAC valve terminal...stopped cutting up, ran smooth. (F) Gas mileage dropped bad, was getting 30 mpg average, might be getting 18 - 20 now, but when it's cutting up at idle sometimes but not every time you can smell the rich burn out the exhaust pipe. (G) Weak when messing up especially up hill. But will still hit higher speeds on level or down hill. Kind a feels like dead miss or turning key on & off. (H) Got warm one day, car running good, turned AC on, boom, starting cutting up, but did not stop when I cut AC back off. One other day cut it on, started cutting up, left AC on, within 5 miles started running normal. (I) Time of day, temps, nor amount of running time seem to matter, does it whenever. After tinkering & researching I want to think it is a problem with one of three things and in order as I list them: (1) IAC Valve - Because worse at low speed or slowing down, bad MPG, unplugged IAC & idle smoothed out, While IAC unplugged, did not get trouble code, so may be sticking from being dirty. (I HOPE) When it did reach operating temp. (closed loop) car idled up high. (2) TPS - Since it seems throttle actions effect problem, may be dirty & sticking. (3) MAF - May be dirty & sticking since all 3 of these would be working closely together in their functions & unplugged MAF when tinkering and got trouble code when I did. Oh, also tried unplugging Transmission sensor, no difference & got trouble code when I did. So far the only thing I did not get trouble code on when unplugged was the IAC Valve. Thanks in advance for any input and suggestions.


Ok, got my car running right. Just updating because I have noticed A LOT of folks have started and did not finish posting fix or not. So, my problem a combination of things. Main problem was ICM was weak, going bad which caused overall weakness in engine power along with a couple of vacuum leaks (found using cigar smoke test) in lines at connection points as well as leak around Idle control valve, O-ring was bad & had gotten sucked in & stretched causing air gap and throttle body, MAF, TPS, & IAC Valve were all pretty dirty, especially MAF, it was extremely dirty. The intermittent failing of the ICM was throwing me off on the major problem. Had been doing all the little tests on it by cooling it down, tapping on it, checking spark, and such as well as having it tested at 2 parts stores in the beginning which said it was good, but it just had not broke down enough to catch it. So I hope this helps anybody else that has problems.

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