1990 Buick Century - Stalling Problem

Sorry can't help - but can sympathize. Had similar problem with an '89 Alfa T164 I used to run. Not as bad - usually got it restarted in 5 - 10 minutes. Problem came for a month or so, then cleared up for a few months, only to recur. No explanation.

Tell him to make sure the oil return ports are clear. Some earlier models had a problem with the ports being too small and crusting over, this stopped the oil from getting back down to the engine effectively. Takes about an hour for it to drain back.

I'm not saying that this is the specific problem, but it happened to mine.

Good luck.

Where are the oil return ports you are talking about? How would this explain the problem?

StandardsGuy

Where the oil return holes are depends on hat engine you have. Any oil return holes will be designed to allow oil from the rocker arms to drain back to the oil pan. Access to the return holes is from the rocker arm area. Try this test. Allow the engine to run long enough to reach operating temperature. With the engine running, remove the dipstick, and wipe it off. Shut off the engine, and as quickly a practical, check the oil level. Mentally make a note of the level, or measure the distance and write it down. Wait 3 minuets, and check the level again. If the two readings are the same, forget about it. If the oil takes that long to get back to the oil pan, your oil holes are clogged, and need to be cleaned.

If the oil does not get back to the oil pan as fast as the engine is pumping it , the fuel pump that will not run with no oil pressure, stops running. If you had this problem, you should see the low oil pressure light come on. they both use the same switch. (your low oil light does work doesn't it?)

The fuel pump is in the gas tank. Does it still depend on oil pressure? The pressure light does work.

Yes. Chevy Vegas were the first cars that I had heard of(there probably were others that had them for safety reasons if they had electric fuel pumps and were involved in an accident) that had the this low oil pressure fuel pump cutoff, I guess because of the fragility of the cylinders. (They had an innovative process of etching away the aluminum cylinder surface, leaving some sort of silicon matrix as the wear surface as I very vaguely recall. If anyone knows more about this, please comment. It might be a process that can be utilized by others, though it is probably proprietary.) A lot of people jumped the pressure switch just to get home and trashed the block (until re-builders figured out how to salvage them although the rebuilds were marginal at best).

I was lucky enough to be employed at a Chevy dealer in Brooklyn NY. in the early 70s. We must have done a Vega block twice a week. There was no engine stand there. We just used some wooden crates nailed together to support them. The replacement engines came as a short block. I don't think the crank came with it.

The start of the problem was the back area of the head gasket. There was a long stretch of a water jacket between the two back head bolts. When the engine was run hot, the gasket could shift, allowing coolant into the cylinders. The combination of coolant in the cylinders and the iron piston rings and the aluminum cylinder walls would gall. We would attach electric wire to a 194 light bulb, and lower it into the two center cylinders. From that location you could see the destroyed cylinder walls. An improved head gasket with a support between the cylinder wall sealing area and the coolant jacket would stop the problem. But it was too late for the Vega.

Is the engine turning over when you crank it? If not, clean and tighten the battery cables (both ends of both cables) then load test the battery.

If it is turning over, check for spark. It could be heat soak in any of the electric ignition components. Try a can of compressed air to instantly cool one component at a time as a test.

Some of the OBD testers also read the common older systems. Check the reader that you have, or have access to for that. If not, the code reading technique for the GM cars was simple. Key on, eng off. Touch the two connections in the top right corner of the diagnostic link connector together, and the check engine light will flash codes for you. WARNING don't take my word for the pin locations without looking up code retrieval for an older GM as the connector has been mounted differently in some years. I am certain that the correct connectors were top right, but the connector housing could be sideways or inverted. Check first. Good luck.

Hi bob_c,

We got a repair manual, and the top right connectors A,B are the ones to short. It only flashed 12, which means the diagnostic mode is working, no other codes flashed. When shorted after the engine is running (field service mode), quick flashes occurred, indicating open loop. What does that mean? I could also use a 3.9K resistor to enter backup mode, but since the book has no list of codes, I don't know what good it would do.

S

Once the engine comes up to operating temperature, the ECM will take the information from the O2 sensor, and fine tune the mixture to maximum efficiency. That is called closed loop. Before that happened, it is in open loop. The car will go back to open loop if certain actions happen. One of them is Wide Open Throttle. I don't remember the rest.

Forget the oil problem being suggested as your problem--You've either have an ignition or fuel problem..arm yourself with a timing light and locate the throttle boby fuel line input (will have a valve silimiliar to your AC access/bleed valves) located just behind the throttle body.

Warm the car at home (under load if you have to get it to temp)-

1-turn if off and attempt to restart-Keep running/restarting until you encouner the problem.

2-quickly check spark on any cylinder (have someone crank car over while checking for spark).--If no spark you've found your problem (ignition)--start lookin at distributor components (probably HEI), especially the coil and then connections,internal pats, etc--relatively inexpensive fix when you find it.

3- 2 is ok--reach behind throttle body while cranking (if your model is fuel pump in tank) no need to crank engine , just turn ignition "on"--depress valve stem in fuel line fitting or use an appropiate fuel pressure guage fitted with a typical tire valve attachment that will depress the valve stem when attached--pressure should be around 7--12 lbs--if no guage is available just insert the hose (air hose equipped with valve attachment ) into a jar and turn key "on"--if all is well, fuel should quickly fill the jar with noticable pressure.

If this vehicle is "carburated"--follow the same instruction in 1 "ignition".

If ignition is good--crack the carburator fuel line fitting at the carb to see if fuel is present while cranking.

If "vapor lock" is indeed your problem in the end--cut out a section of the steel line to the carbierator and insert a section of rubber line somewhere convenient. Make shure you use rubber line suitable for gas (containing ethanol) or the rubber will slowly disinagrate plugging up the carb jets.

Good luck--Jim

My money is on the ignition

Good suggestions. I told him he needs to determine if he has spark. The timing light is a good way. He will be leaving with the car in a couple of hours, so some of this may have to wait. There is a fuel return line which is supposed to prevent vapor lock, and I never heard of it happening below 90 deg. F. Thanks.

If this car has a fuel pump mounted in the gas tank you may have a dirty fuel pump sock filter that gets plugged up and then after it sits for a period of time the dirt settles and fuel flows to and through the pump again.

The in-line filter has been changed. One of his friends thought there was another filter (in the pump?). Where is the sock filter you are talking about?

On the end of the intake tube. Sometimes plastic, sometimes woven synthetic, sometimes brass mesh.

I had an '85 Olds with HEI that would start cold and run fine till it warmed up. Then when pulling from a stop it would cut out and not start for a half hour and then repeat the problem. If I was on the highway, I could drive forever as long as I didn't stop or jump on the gas. Distributor pick-up coil (not the ignition coil).

Hi, StandardsGuy,

What item is featured in your avatar? If it's a solenoid, then I think the no-start problem is right under your nose.

Many GM engines had the starter solenoid located too close to an exhaust pipe. The effect was that the solenoid would work just fine when it was cold (cool). Then, after the engine was run long enough to get the solenoid hot, it would fail to pull in when trying to restart a hot engine. Allowing it to sit about 30 minutes was just enough time to have the solenoid cool sufficiently to work normally.

I had that problem on my Chevy van, which I solved by installing a new starter solenoid next to the battery. A new solenoid is pretty cheap and can be found at any auto parts store.

BTW... my previous message would apply only if the engine fails to crank, until cooled off. If it cranks, but doesn't start, then the problem is not the starter solenoid.

Or the starter, which can also become heat soaked for the same reason; too close to the exhaust. If the hot engine can be immediately restarted, but cannot be after being off for 5 or 10 minutes, then can be restarted after an hour, heat soak is a real possibility.

If it is a common problem with a particular model, chances are aftermarket insulating blankets or shields are available to prevent the problem. However, if the original device has been thermally damaged, you may have to begin with a new one and install the heat shield on the new device.

I had a very similar problem with a 1989 Ford Econovan, big boy, started just fine cold but once it was up to running temperature and I stopped somewhere, it wouldn't start again until the engine had cooled down somewhat (like G.J. to Delta). The problem..a defective electronic ignition module. It ran just fine until you turned it off, that could be an hour or hours, only failed when it was shut off. There was a factory recall on it eventually and a new module cured the problem.

It would crank, just didn't start.

I had a similar problem with a 1984 BMW318. And i replaced the fuel pump $60, then the ignition module ($500)- only for the problem to return on both occassions. It appeared to be somehow temperature related. But when it stopped while driving over a bump in the road (pothole) on a cool night - I asked an autoelectrician to go over the lot.

A week later ($300 labour) it turned out to be $7 conrol solenoid under the dashboard, which was damaged and intermitently functioning - depending in the temperature and vibration.

It may be either defective ignition pick-up OR vapor forming in the fuel line ontop of the engine. There is a pressure regulator where the return line branches off. If that is not holding back-pressure on engine shut off, vapor WILL form in th fuel line and cause the problem. There is also a anti-return check valve in the fuel pump discharge that is supposed to keep the system pressurized on shut down. You can perform a 'leak-down' test on the fuel system by connecting a fuel system pressure guage kit to the access port (screw connector similar to tire valve) on the steel fuel pipe. The pressure should hold steady for at least 30 min. after shut down. Even a tiny leak back will cause the pressure to drop quickly, allowing bubbles to form in the lines to the fuel injectors.

I would suggest the erg valve bolted under throttle body they get sticky I had lots of late 80s Monti Carlos with v6 (injected)throttle body styles.The Exhaust gas recirculator acts like a choke and gets stuck , If the other suggestions don't pan out try it . I kept an extra one around it happens.

The problem is likely to be flooding caused by worn fuel injectors. But I suggest your son does a complete tune up first including replacing the ignition wires if they are original, old or have high resistance. If the problem persists check the signal at each injector. Unfortunately I don't know of any test for worn injectors, but ask the local Buick dealer for advice. You just have to replace the injectors and hope that solves the problem.

Dennis Waller

Foreign Auto Service

Have you checked the fuel filter? Also, consider the possibility of problems with the coil.

I'll give you 10 to 1 odds that it is the pickup coil under the distributor cap (Hall Effect Sensor).

It appears to have 3 spark coils, but nothing that looks like a distributor cap. The 6 spark plug wires are coming out by the 3 coils.

StandardGuy--from Guest

As I stated in my firsrt reply--"forget the oil problem. Although you didn't specifically state the engine turned over but wouldn't start-I read between the lines and assumed it did turn over (eliminating the starter) as suggested several times.

You must first identify "Ignition or Fuel"

Then proceed from there !

If you have good fuel pressure at the valve behind the "throttle body", forget the pump/filter/etc. Although it may look like a "fuel" problem it may well still be electrical-fuel injectors in throttle body may not be gettting voltage to fire. (it's still a fuel problem)

You'll have to approach these problems with a lot of logic and common sense--after you have spent several hours looking for the problem, take it to a facility that has diagnostic equipment and save yourself some grief and busted nuckles.

Good luck-Jim

That sounds like a double negative to me.

1) Tell the man to quit and pay some one to guess the problem.

2) Hide behind Guest status.

There are better minds here at CR4, than at most repair facilities. No one here is going to sell him the most expensive thing he can think of to pad the profit line, in case he guesses wrong. How many mechanics were out of elementary school when this car was made in 1990?

This is as much a challenge to the StandardsGuy as getting his car to run on water.

Good evening Bob C

No--Not a double negative--just common sense.

Since I have no knowledge of his automotive expertise ,there comes a time when one has to "fold" and yield to other's expertise for assistance--After 50 yrs of automotive experiece, I still have to from time to time.

And I wasn't "hiding" behind the "GUEST" status--I just forgot to log-in before I offered my reply to assist him .

You obviously made some assumptions bout me 1) & 2) --which were both wrong !

donzi386

Your replies are much more respected when you have a name.

The purpose of this thread is to have the combined knowledge of CR4 to help guide him through this problem. Only he knows his limitations mechanically. And yes of course we all need to go to the well at times. My feeling was that there were still ways to test the vehicle that did not require any complex procedures. Thank you for the courteous reply.

Bob

You're entirely welcome--

Jim--Palatka, Fl.

Moisture in the distributor cap? This is nothing more than a WAG, but it is easy to check.

Bill

I yhink the problem is VAPOR LOCK.

Some fuel line (maybe inside the engine compartment or near the exhaust) is not well insulated and the fuel inside turns into fuel vapor. That, being a gas instead of a liquid, is compressible and that creates a "bubble" that is compressed and prevents liquid fuel from reaching the desired parts.(fuel injection system, etc..)

When it cools down, it runs well again. You are right. It is vapor lock. It is almost completely independent from outside temperature.

I have several friends who hace experienced similiar issues but only when the gas tank level is below1/4 tank. They claim the fuel pump gets hot and just shuts down until it cools off. Don't know if this help, but the key is tis ussually only happens at when the gas tank is below 1/4 tanks.

good luck

you guys are throwing a lot of stuff at this guy some of it makes sense but some not so much #1 a 1990 buick century came with a 2.4 4 cyl or the more common 3.3 neither one had HEI they have coils over a module with crank or cam sensors there is no cap and rotor on either engine your fuel pressure should be 40 psi when you turn the key to run and should drop off after 3 seconds when you crank the engine you should have at least 40 psi, max output is 60 psi if you see more than 60 at any time your return line is blocked there is no anti drain back valve in the presure regulator.vapor lock?I don't think so.with those pressures the fuel line would have to be mounted on or inside the the exaust...check spark...got it ...check fuel pressure...got 40 to 60 psi...good now crank the car with your foot on the floor wide open throttle...does it start....you need plugs..if no start and you have spark and fuel your spark is wrong and you need a module these cars had very few no start problems...ie fuel pumps,ing module,coils and yes oil pressure sensors but if you have fuel pressure while cranking it's not an oil pressure problem good luck

Sounds like the fuel pump or fuel solenoid is wearing out. As they get to the end of their life they will get hot during operation and will not work immediately after being shut off. After a cool down period it takes less energy to actuate or energize them and they will work again. Because it takes less energy to keep them active they usually will work fine once energized. But it is just a matter of time before they fail completely, possibly while driving down the road. Hope this helps.

The fuel pump was replaced not long ago. Where is the solenoid, and what is it's purpose? I think my son said it would start immediately after being shut off hot, but not after 10 minutes. He's not here now, so I can't verify that.

I had this EXACT same problem with a 1989 Buick century, V6 engine. The problem turned out to be the injector solenoids. The next time this happens, unplug ONE of the electrical connections to an injector. The car should start , and get you home.

Apparently the solenoids electrical resistance drops over time to the point they will not work when warm. You can buy new injectors at $50 @, or visit a wrecking yard as I did, and check the ohms at the connector, select injectors with highest resistance, as I recall it will be in the 12 to 15 ohm range. The injectors are simple to replace, and with 6 new/used injectors, the problem has not repeated.

This is a common problem with these engines. The fuel pressure regulator, which is located on the fuel rail toward the front of the car is bad. You can confirm this by pulling the vacumm hose off the regulator, if you smell gas, the regulator is bad.

I think U guys are on the right track with the fuel injectors. there is a simple test that requires no special tools to do. After the car has been brought up to temp ,and the problem occurs and wont start, carefully remove the spark plugs (they are allm. heads removing to fast can cause stripped threads) if any are wet or smell like fuel u found the bad injector. this must be done when the problem occurs wait to long and the plugs will dry. If no fuel found on plugs look for the fuel pressure regulator vacum hose remove it and check for fuel in side if fuel is present in the hose the regulator is leaking and needs to be replaced . the regulator is not likely the problem though.

StandardsGuy:

been following your sons car problem for several days (as "guest") cause I forgot to sign in--when it was noted by someone, I did sign in as "donzi".

That being said--did you or son ever nail down the problem (ignition or fuel) ???

I look several times a day to see if you've found the problem !

donzi

Thanks everybody for your replies. I'll have a lot of things to try when my son gets back. Looks like some real good suggestions to nail it down.

S

hey standards guy....good luck if you need any wiring diagrams e mail me at mr.wrenches@yahoo.com.....by the way the fuel pump relay is located either behind the right front head light it is the first one closest to the radiator the signal wire is green with a white stripe check the fuse right next to it good luck

I'm experiencing the same issues with my father in laws Car, which is now my daughters. Standardsguy, what was the repair that worked for your sons car?