1997 Chevy Lumina No start condition

Tiny
AMANAMAN1
  • MEMBER
  • 1997 CHEVROLET LUMINA
Engine Mechanical problem
1997 Chevy Lumina 6 cyl Front Wheel Drive Automatic 155K miles

3.1 engine cranks but won't start. Fuel circuit is working and stays pressurized. Seems to have a weak spark coming from all 3 coils. It's pretty cold outside (10F) and I wanted to know if it is possible that all three ignition coils could be weakened to the point where when cold, they could all produce weak spark at the same time? Vehicle has always run fine, no misses or failure to starts, except when it's very cold. Have to crank it a couple extra times sometimes. Battery is new and it cranks strong rpms.

I pulled wires from all three coils (plug end) and checked spark to ground with a tester and all three made a weak spark that won't jump the full length to ground on my tester (adjustable tester where you turn the screw to set the length of the air gap for the spark to jump, if you are familiar with this kind of tester). The sae gap on this tester is supposed to be set at 36-40 but my spark won't jump above 25-30 and it's a real thin blue line spark at that, not that flat snappy big blue one.

Since I am getting at least a weak spark that tells me the crank sensors and everything else is working or it wouldn't even spark at all I would assume? Could a bad ignition module cause the coils to produce a weak spark or is it an all or nothing thing there? Wanted some input before I spend 100 bucks on coils as it seems odd that all three could be bad in the same way at the same time. They are the original coils. Primary coils resistance measures.3 -.5 ohms. Secondary coils resistance measures right at 5K on all three at around 10F to 15F degrees outside. My hands are numb!

Oh, when I was done for the day messing with this, I also inadvertently broke (more like shattered in the cold and now don't know where the other end is supposed to go) the plastic vacuum line attached to the fuel pressure regulator. Will the vehicle still start and run (assuming the ignition problem is fixed) with that line off or do I need to have it connected? It should still deliver fuel I think as that is on the return line but please advise also. Again, that happened well after the no start problem.

Thanks
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Friday, January 29th, 2010 AT 7:04 PM

12 Replies

Tiny
RACEFAN966
  • EXPERT
Well I looked up the coil resistance and it is good so I would suspect the module at this point. As for the plastic line to the regulator I would use a piece of rubber vacuum line to go over the plastic line and call it fixed. It will start with it broken but the fuel pressure will about 10 psi higher so don't run long that way ok. Let me know what you find.
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Saturday, January 30th, 2010 AT 8:54 AM
Tiny
AMANAMAN1
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Thanks.

Just went ahead and replaced the ign. Module and coils. Spark looks better and seems to be hot enough with a different spark tester but still no start.

Checked the crank sensor.850 ohms and.4 -.5 vac when cranking so it seems within specs.

Double checked fuel pressure at the rail @43psi and it holds.

What next? Injectors not firing? Seems like they are as I can smell gas after I try to start. Need to pull the plugs and see if they're flooded I guess but ran out of daylight and my fingers are frozen as it's still quite cold outside (15F). Also did the hold the pedal to the floor thing while cranking to clear the cylinders but didn't help.

Is it possible something in the fuel rail and the injectors could just be frozen since it's so cold? Never had this happen before though and the car has always sat outside.

What's the best way to test the injectors to see if they're firing and delivering fuel? Does fuel in the cylinders indicate enough? I see a 10 pin connector on the wiring diagram for the injector circuits but don't know what voltage I'm looking for.

Any ideas?
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Saturday, January 30th, 2010 AT 9:46 AM
Tiny
RACEFAN966
  • EXPERT
Ok I would like you to do two things ok. First spray some THROTTLE body cleaner in the intake and see if it starts? Then if you would unplug the mass air flow meter and see if it will start and idle. Let me know what you find here and we will go from there ok.
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Monday, February 1st, 2010 AT 12:03 PM
Tiny
AMANAMAN1
  • MEMBER
Alrighty. Went ahead and replaced the spark plugs and wires first as they look like they needed it anyway. She's definitely sparking good now on all cylinders but still no start.

I unhooked the rubber intake boot from the engine side of the MAF sensor and sprayed starting fluid into the intake. No go. Not even a sputter. That was with the fuel injector fuse pulled as I didn't want to flood the cylinders. Waited a few minutes. Tried more starting fluid. Nothing. Put the injector fuse back in and tried to start, then she sputtered a few times and backfired one or twice but no start.

Unplugged the MAF sensor and no change. Tried it unplugged with and without the injectors and with and without starting fluid. No start. Pulled the front plugs and they have fuel. Tried to start again and just a few sputters and a backfire.

I can see the rocker arms moving through the valve cover oil hole when cranking so the cam is turning, but I'm wondering if she slipped the timing chain? Is there a way to test or just a process of elimination? 156K miles and it's never been replaced.

Whatcha think at this point?
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Monday, February 1st, 2010 AT 3:41 PM
Tiny
RACEFAN966
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I would like to check the camshaft position sensor and then the cranksensor. As soon as I have mitchell back I will get the procedure needed. Let me know if you are comfortable enough doing some ohm tests and you do have a digital multi meter?
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Tuesday, February 2nd, 2010 AT 8:44 AM
Tiny
AMANAMAN1
  • MEMBER
I already checked the crank sensor and it checks within specs (see previous post). Not sure where to test the cam sensor, as far as what harness the wires are in and yes I'm good with a meter. Thanks
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Tuesday, February 2nd, 2010 AT 8:56 AM
Tiny
AMANAMAN1
  • MEMBER
Well, I did a compression test today and here's what I found:

2= 160
4= 165
6= 175
1= 175
3= 105
5= 170

Did each one twice to be sure. Obviously the #3 has an issue but I don't know what is a "good" compression pressure for this engine anyway to determine if the timing has jumped. Please advise what you think. Thanks!
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Tuesday, February 2nd, 2010 AT 5:36 PM
Tiny
RACEFAN966
  • EXPERT
Ok compression don't look like it would keep it from running. I would like to go back to the crank sensor. Ohms on it are good but I would like you to check the voltage to it with key on engine off. Let me know what voltage you find. After checking the crankshaft sensor I would like you to unplug the map sensor and try to start it let me know if it starts and runs ok. If it don't start then I would like you to check spark plug wire resistance. Then unplug the coolant temp sensor and ohm it get back to me with the ohms and the temp at the time (do this when the engine is cold) Let me know what you find here too.
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Wednesday, February 3rd, 2010 AT 8:43 AM
Tiny
AMANAMAN1
  • MEMBER
Well. Even though the crank pos sensor checked the same as before (850 ohms and.5 volts when cranking) I went ahead and replaced it just to ease my mind and the damn thing started right up.

By the way, what a friggen pain that was to change a $20 part. How is it normally done? With the ignition module removed I laid across the engine like a playboy centerfold and reached down and around the exhaust by feel. Of course it was stuck in the block and took an hour and a half to get out but did it all by feel but crap there's got to be an easier way.

Anyway the spark I am getting now is way hotter and brighter than what I had before when it wouldn't start. I honestly thought there was enough spark there but I guess not. If the crank sensor was bad (which it obviously was), why was I still getting a spark? I didn't think the ignition module would fire the coils if it didn't see the crank voltage? Maybe I'm wrong.

Hey listen, I really appreciate your help. Thanks for helping me.
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Wednesday, February 3rd, 2010 AT 8:21 PM
Tiny
RACEFAN966
  • EXPERT
Well first off glad to hear it is running again. Now just to answer you questions first it is normally done on a rack from underneather. The other question it was seeing voltage just not at the proper time or the right length of time so there. See the sensor sends either a 7x signal or 24x signal depending on which one you have and the module converts this signal to 3x and fires the coil if this isn't proper then it will have a weak or no spark.
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Thursday, February 4th, 2010 AT 9:05 AM
Tiny
AMANAMAN1
  • MEMBER
Got it. Obviously can be tricky to diagnose for the layman like me. So I have both a 7x and a 24x sensor plus the cam sensor so I assume all 3 could cause the same problem with weak, out of time, or no spark? Anyway. Thanks again I appreciate the help.
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Friday, February 5th, 2010 AT 9:54 AM
Tiny
RACEFAN966
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You got it great. Great job fixing it too feels good to fix it yourself. Anyway if there is any other problems just ask. Thanks again and have a great day.
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Friday, February 5th, 2010 AT 10:15 AM

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