1990 3.1 Lumina, no start/hesitate/throttle problems

[bobotech]

I am posting on behalf of my friends. They got a car from their grandpa, its a 1990 3.1L Chevy Lumina with only 68k miles on it. Runs decent enough and is in clean condition.

 

However they have been having some problems with it this past week. They have had the car for 3 weeks now.

 

A week ago, they took it for a long drive (2 hours each way) and had no real issues other than they noticed rotten egg smell (cat) once in a while.

 

This past Sat, they were going to go on a 1/2 hour drive and they made it halfway when their car started surging/dying and they got off the freeway. Pulled into a gas station and tried starting it. Apparently it started once so they shut it off and tried to start it again, no start.

 

I got there and checked for spark, spark seemed fine and strong (blue white). I checked for fuel pressure by opening the schrader valve and poking something into it and got a big ole spray of fuel coming out, seemed okay. Tried starting it again, nothing.

 

They had it towed to the house. While at the house, noticed that the schrader valve was leaking fuel while trying to start it. Also the car did start up at that point (several hours after it was dropped off by the tow company). She tried to drive it and it died.

 

We then replaced the schrader valve with a core tool and a new core, no more leakage. Also replaced the fuel filter. Checked the fuel pressure with my pressure tester. With the key turned to RUN (not Start), it jumps to about 38. While starting it, it varies. If it ran, it would hover between 38-45 depending on RPM.

 

She then took it for a small test drive. As soon as she was hitting the gas pedel, it would die.

 

We coaxed it back home by leaving the car in idle and putting ti into drive and "coasting" back to their drive way. (she was a block away). If I opened the throttle plate VERY slowly, I could get it to start to rev up but then it would die again.

 

The Next Day:

The would not even start at this ponit. It would attempt to and die immediately.

 

I wondered if it was the TPS sensor. As a quickie test, we bought a new sensor. I just unplugged the old one and plugged the harness into the new one and had her turn the car on. Even though the new sensor wasn't hooked up to the throttle body, at idle, it still should operate within specs to allow it to idle at least. No go, same symptoms. Would barely start and die right away.

 

The owner then wanted to replace the computer since she read that others have had simliar problems. We bought a new computer. When I opened the plastic panel to remove the old computer, I coudl tell that someone had been in there before. None of the clips that held the computer in place were present, the computer was just laying there. The clips were all broken. The cover on the back side that covered the prom was missing. The computer did say "Delco GM" on it though, didn't appear to be aftermarket. We then swapped proms into the new computer and putt it back in place.

 

Started the car and it started up beautifully and we took it for a test drive. The owner mentioned that the car surged a couiple of times but otherwise seemed fine.

 

She took it to work today. On the way home from work, the car stalled and she could not get it started back up again, just like on Saturday. So at this point, I am really at my wits end and am not sure where to go with this one.

 

Any suggestions?

[94 olds vert]

This sounds like the same problem that I'm having on my Grand prix. 3.1l. I'm pretty sure I have a problem with one of my injectors(probably more than just one). You should check those.

[Grand Moff Joseph]

Welcome to the board! You picked the right place to get some help.

 

I'd also look at the coils and the ICM. A dying ICM can play havoc with the consistency of the coils and overall spark timing. If you feel like lopping off the Upper Intake, you can resistance test the injectors (and replace the EGR valve while you're in there).

 

Hope that helps!

[bobotech]

Where is the ICM? Its easy enough to change the gaskets. I used to have a 89 Chevy Caviler Z24 that I replaced the 2.8 engine with the same 3.1 engine and had to do the gasket swap. That was many years ago.

 

So you guys are thinking its timing/spark issue at this point?

 

I'm going to see if there are any codes in the system tonight when I get home using the paper clip trick.

[bobotech]

Should I replace the CPS since thats pretty easy and easy to get at?

[Grand Moff Joseph]

Where is the ICM? Its easy enough to change the gaskets. I used to have a 89 Chevy Caviler Z24 that I replaced the 2.8 engine with the same 3.1 engine and had to do the gasket swap. That was many years ago.

 

So you guys are thinking its timing/spark issue at this point?

 

I'm going to see if there are any codes in the system tonight when I get home using the paper clip trick.

 

The ICM sits directly underneath the coil packs on a 3.1. To access the coils, you'll need to move the upper dogbones and the coolant overflow tank. Basically, the coils sit on top of the ICM, and they form one assembly together.

[bobotech]

The ICM sits directly underneath the coil packs on a 3.1. To access the coils, you'll need to move the upper dogbones and the coolant overflow tank. Basically, the coils sit on top of the ICM, and they form one assembly together.

 

Ugh, that is a pain in the ass to change. I remember having to change my coil pack out on my old Z24 years ago.

[Grand Moff Joseph]

Ugh, that is a pain in the ass to change. I remember having to change my coil pack out on my old Z24 years ago.

 

Yep, that it is. One thing you can do to make similar repairs easier in the future is to move the coolant tank. 1990s were the only year to get coolant tanks between the dogbones. 91-94 models have the coolant tank positioned along the passenger side wheel well, with screws attached through the plastic cladding and the diagonal brace on that side of the engine bay. Just grab a coolant bottle, hoses and drilled brace from any 91-94 Lumina, and relocation is a snap.

[90V6RedHotLuminaEuro]

Should I replace the CPS since thats pretty easy and easy to get at?

 

I would... that's my guess... and it's cheap... you may want to do the knock sensor while you're down there as well... be careful with the connectors and wires... they get brittle down there after 21 years.

[bobotech]

Still no change. At this point, I am at my wits end. What COULD be wrong with this low mileage "cream puff"? It only has 68k miles on it.

 

Sensors replaced: CPS, Throttle. All coil packs and ICM (under coil packs) replaced. New plugs/wires. New computer/ecm. Air cleaner clean. Fuel filter replaced. No engine codes.

 

The problem seems to occur when it warms up. At first the car starts up with no problem. You can drive it fine too but then very soon after it starts warming up, the engine starts cutting out until it just dies and then you have no start condition.

 

Fuel pressure when cranking the engine jumps to 45 at the scrader valve with my fuel pressure tester.

 

When the engine is cranking during the no-start condition, you get spark (hooked up my timing light to confirm this).

 

Is it the injectors aren't just firing off when they get hot? If so, what in the world could cause all of them to quit firing at once. The engine isn't missing or runningn roughly as it gets hot, it just revs up and flat out dies. If it runs, it idles like glass or it just dies.

 

We are at a loss now. I'm realy not sure where to go with this. I don't feel like replacing the fuel pump but if we have to, then that is what we do next, but why would the pressure tests show good strong pressure even durign the no-start conditions?

[90V6RedHotLuminaEuro]

How 'bout the CPS wiring to/from... and/or all other wiring? Sounds like something is going "open" when it gets hot.

 

I had a '64 Caddy that wouldn't start at certain temperatures... turned out to be a bad ground from battery to block. I had a Ford Escort that wouldn't start at certain temperatures... turned out to be the fuel shutoff device in the trunk... drove me nuts for years... then one day, while looking at schematics, and seeing the sun beating down on the drivers side rear end of the car... ahaaa... This computer I'm working on... Acer Aspire Netbook... when the power shuts off and the battery dies, like after a storm, I have to keep hitting the power button on and off and aim a hot blow dryer at the keyboard till it lights up again.

 

I had a 91 Sunbird V6 3.1 with similar problems... a friend told me a fusible link could be "almost bad" and go open under certain conditions, temperature changes, and or load, like the heater blower fan... and then go back to normal. Sure enough, I replaced one down by the starter that didn't look so good... and that was it. Later I found that the wire going to the heater blower fan was also bad. It had some bad insulation that would rub against the strut tower brace just enough to wreak havoc and then go back to normal. The HVAC shared a fuse with the alternator "turn on" input... once the fan blew the fuse and I lost the alternator. I thought the Alternator went bad... didn't check the fuse... bought a new alternator... who knew the alternator shared a fuse with the HVAC? ...live, learn, etc...

 

A can of "Freeze" spray from Radio Shack or a Heat Gun may help you troubleshoot the exact point of the problem... but most often I've been able to find my crappy wiring after cleaning things up and following it along inch by inch... devices are another story.... sometimes you just have to swap and hope.

 

My 90 Lumina was built 11/89... almost 22 years ago... I recently got it... I replaced the Power Steering pump and the water pump. While replacing the PS pump, I found a great bundle of wires crushed under the reservoir against the engine. Many were melded together with their insulation and some were missing there insulation. I had to do some repairs. I used electrical contact cleaner, carb cleaner, brake parts cleaner, 90 proof rubbing alcohol... whatever... and a brush to clean up the wiring real good and then fix the individual wires as needed... mostly I use Liquid Electrical Tape to repair the insulation... it's easy... sometimes tape... sometimes fusible tape... which is like rubber... sometimes I have to cut and solder and shrink wrap... and then I always replace the black flexible wiring harness coverings... it's cheap and it finishes the job nicely.

 

The old rotten wiring in these old cars can cause problems that can make troubleshooting a threat to your sanity. My compassion goes out to you and yours.

[bobotech]

It wouldn't be so bad if we could SEE the problem. But even during the no-start situations, there is still strong spark and there is 38-45 psi pressure at the fuel rail.

 

At this point, I'm going to have the owner warm up the car, get it to the no-start condition and then yank a plug and see if it is wet. If it isn't wet, then yup, some wiring is someplace acting up causing the injectors to not open or something most likely.

[Crazy K]

could be:

bad map sensor. test by seeing it the car runs better with it unplugged. if so, replace.

bad injector that shorts out when hot. With a multimeter check the resistance of your injectors. they should read somewhere between 11.5 and 12.5 ohms. If you find any that are like 9 or 8 ohms the car will run but may have driveability issues, and if you see any that are like 3-5 ohms, those will short out the computer and cause a no run condition.

[joecutlass]

I had the exact same issue with my cutlass. When i say exact, i mean exactly as you described your problem. It is the fuel injectors. Could be one or more. I had three bad injectors when it started to do it to me, and after replacing those with used injectors, two more went bad, so i went and got 6 new, not remanufactured, injectors. Ohm test the injectors. Im 100% sure this is your problem.

[bobotech]

Here is the catch, how do we find an injector that is almost a dead short only when its hot? If we get the car running and get it to the point where it no longer runs, and then take the time to remove the upper plenum, by the time you are done accessing the injectors, the engine will have cooled off and might give a false reading.

[joecutlass]

I dont believe heat will make a difference in ohm testing the injectors. My cutlass (same motor) did the exact same thing. Started cold sometimes, and when it got hot, it wouldnt start at all. I made the mistake of throwing parts at it. Test the injectors.

[spiderw31]

Here is the catch, how do we find an injector that is almost a dead short only when its hot? If we get the car running and get it to the point where it no longer runs, and then take the time to remove the upper plenum, by the time you are done accessing the injectors, the engine will have cooled off and might give a false reading.

 

The injectors are wired in parallel, IIRC they are in two batches. So 3, 12 Ohm injectors in parallel should equal 4 Ohms. If one or more are dead shorted, you'll get a reading of 0 Ohms, or pretty close. Even if just part of the coil in the injector is shorted, your 4 Ohm reading will lower substantially. Get anything substantially higher than 4 Ohms, and one of the injectors has gone open.

 

You should be able to get at the points to measure from in the wiring harness without removing much or anything at all.

[bobotech]

Good lord, I HATE this car. So we went ahead and pulled the intake manifold plenum. Not a bad job, just tedious but the engine was clean so we didn't even get that dirty.

 

Checked all 6 of the injectors. 4 of them were roughly 12 ohms or so. 1 was 9 (bad) and 1 was 5 ohms (really bad, i guess this one was the problem child causing the computer to shut down when it warms up).

 

So we replaced the, no problem there. Used new seals/fuel o-rings so there would be no leaks. put the engine back together.

 

Started it up and there is soemthing rattling inside the engine now. Sounds like a ball bearing banging around inside the combustion chamber. F***!!! So now to tear it all down and hopefully use a magnet to pull out what it iinside there and get rid of the rattle. And on top of that, the engine was running rough when we first started it up.

 

This car is awful!! I know, don't blame the car, just a really odd to diagnose problem and then our fault for letting something fall into the intake ports or the fuel injector ports but still..

[rohrmann@cox.net]

Good lord, I HATE this car. So we went ahead and pulled the intake manifold plenum. Not a bad job, just tedious but the engine was clean so we didn't even get that dirty.

 

Checked all 6 of the injectors. 4 of them were roughly 12 ohms or so. 1 was 9 (bad) and 1 was 5 ohms (really bad, i guess this one was the problem child causing the computer to shut down when it warms up).

 

So we replaced the, no problem there. Used new seals/fuel o-rings so there would be no leaks. put the engine back together.

 

Started it up and there is soemthing rattling inside the engine now. Sounds like a ball bearing banging around inside the combustion chamber. F***!!! So now to tear it all down and hopefully use a magnet to pull out what it iinside there and get rid of the rattle. And on top of that, the engine was running rough when we first started it up.

 

This car is awful!! I know, don't blame the car, just a really odd to diagnose problem and then our fault for letting something fall into the intake ports or the fuel injector ports but still..

 

"So what did you find rattling around inside the motor?"

[R Crusoe]

Sounds like my experience with 1989 Grand Prix SE with 2.8 L and 5 speed manual. Engine would start ok, then when accellerator was pressed, the engine would bog down and then die. This happened on a trip to Florida from Chicago and about 10 PM on a dark and lonely off ramp from I-10. Had car towed to mechanic in Chattahooche, Florida and he spent three days investigating problem and by accident found one of the injectors was shorting out. He replaced only 1 injector and I was on my way. Since then I've had other instances of the same problem and have finally solved it. Replaced the crankshaft position sensor and all 6 injectors. Have learned that original equipment injectors for 2.8 and 3.1 engines tended to short out and when one goes, the way it's wired, causes the engine to shut down. Replaced all original injectors with Bosch DRI injectors obtained from Linder Fuel Services in Speedway, Indiana. The engine never sounded better after job was done. Takes about an hour to remove plenum, fuel rail, and injectors and reassemble. I think I could do it blindfolded now for all the times I've had that plenum off.

[pappy001]

hello everyone--glad to have found you...much the same issue here---91 lumina euro 3.1.idle surge and uneven---when warmed up misses badly then shuts down and will not re-fire.so far-injectors test good ..fuel pressure excellant and holding pressure after shutdown..so far have changed crank sensor ,plugs ,plug wires ,ignition module,new ecm , years back had a fried wire in harness beneath the alternator in channel there, have trouble shot area again and no problem there.can the o2 sensor or the map sensor cause this problem ? i see the map referred to above,but never had a map sensor go bad on anything before(lucky i guess) .i am at a loss and about to send an otherwise

good running non-oil burner down the road despite always loving this car all these years.i am now at the point of tossing money out the door and guessing.

[90V6RedHotLuminaEuro]

Quick Guesses: Idle Air Control Valve (IAC)? Throttle Position Sensor? ...when the engine is running, Check your vacuum, should be 17 to 21hg's, steady, at idle which is i believe normally about 750 rpm... I think you can borrow a Mityvac from Autozone if you need a vac guage... while you're at it, check/clean or replace your PCV...

[pappy001]

i will get the vacuum re-checked this week --weather permitting---thanks --by the way--i have the book --but just in case--exactly where is the best place to do the vacuum check at ?

Edited June 10, 2013 by pappy001