97 aurora wont start

[chad millett]

Ok....A friend of mine got this car cheap because it stalled at stops. It also ran rough. The fuel guage would go from empty to full. Yesterday the car stalled out and wouldnt restart for an hour or so and even then it started hard. I drove it home for her but it barley made it. I changed the fuel pump because the dealer that sold it thought that might be it. It started and ran rough like before after installing the new fuel pump.... Then it stalled and wont start. It fires but it still wont start. If I step on the accelerator it backfires a little but still no start. I checked for spark at the plugs in the front and they all have spark but its hard to tell if its a regular pattern or not. So its getting fuel to the fuel rail and at least some spark but it wont start.
Any ideas would be greatly appreciated.
Thank you

[mentel]

Have you tried swapping out the coil packs yet? I have had similar problems on the GM 3400 and I replaced the coil packs and it ran great.

[chad millett]

I have not. I was thinking that if I had spark it wouldnt be the coil packs. Did you replace the ignition module with coils or just the coils?

[mentel]

I'm going to read up on your motor here. With the v6's there are 3 coil packs and you can take them all off seperately. May or may not be similar with the v8 you have.

[ghutchin]

Have you scanned for codes? Sounds like the symptoms of failing crank position sensors.

[chad millett]

Yes it has 4 seperate coils. They are all producing some spark.

I have not scanned for codes because I dont have a scanner and I cant get the car to Advance with it not running. I think I am going to buy the cheap $70 scanner. I always need it anyway.
If it was the crank sensors would it show a code for that? Could it be possible to have some spark even if these parts are bad?

[ghutchin]

If they are producing consistent spark then the crank sensors are probably okay. First I would get a scanner and check for codes. Next I would get a fuel pressure gauge and check fuel pressure. Even though you replaced the fuel pump, it is very common on these cars for the wiring harness to the fuel pump to overheat and melt. Assuming no codes and good fuel pressure (40-45 psi) then I would do a compression check.

[chad millett]

Im having a hard time getting a scanner. I cant read the codes yet.
The last time I did when the car still ran it said multiple cylinder misfire and multiple cylinder misfire pending. The engine light would flash the whole time.

It has great fuel pressure but when I checked the front spark plugs only one was very, very soaked in fuel. The other three were dry.

I took the vaccuum hose off the fuel pressure regulator to see if it had gas in it but it didnt. I believe this is how you check to see if it is bad.

If we have to take the trial and error route (which I hate throwing parts at a vehicle just hoping one will fix it) what should I start with......?

I was thinking....
the whole coil pack including the ignition module.......$85 shipped used
crankshaft and camshaft sensors
fuel pressure regulator
computer

I just cant believe this damn car wont even start now.

[ghutchin]

Which plug is wet? I would check the other plug that fires off of that coil and see if that is also wet. That may be your problem.

Another issue could be a leaky injector. Did you say that you have a fuel pressure gauge? What is the reading? does the pressure bleed off when you turn off the car.

I do not recommend throwing money at this (Ive been down that road too many times), I also would not recommend wasting money on a used coil pack set unless you determine that you have a bad coil. But, in that case I would get a new coil. $35 from Rockauto.com

Its sounding to me like you have a bad coil. First check the other plug. Then check the primary and secondary resistance of the coil pack. The primary should be around .5 ohms and the secondary should be around 9k ohms.

[unioncreek]

I get my coils from the junk yard for free, beats paying $35 for them. Have you changed the fuel filter yet? If not that's the first thing I would do. What kind of pressure are you seeing at the test port? Have you checked the fpr yet?

Bob

[chad millett]

Originally Posted by unioncreek

I get my coils from the junk yard for free, beats paying $35 for them. Have you changed the fuel filter yet? If not that's the first thing I would do. What kind of pressure are you seeing at the test port? Have you checked the fpr yet?

Bob

I just put a brand new fuel pump and filter on.
It has plenty of spray coming from the valve on the fuel rail when I push it. I dont have a fuel pressure guage. The plugs are all soaked when I checked them today. I put new ones and and still no fire. When I check for spark there is some but now im thinking that its irregular and sometimes weak....like yellow and small and sometimes it makes a good snap with blue spark.

[ghutchin]

There is a ground wire that is connected to the corner of the ignition control module. Is that connected?

I have a suggestion to rule out the coils:

1. Unplug your injectors.
2. Pull both spark plug wires from one of the coils. Now crank the engine. You should see spark arcing to ground and between the terminals. It should be pretty obvious.
3. Repeat this for each of the coils.

If all of the coils look okay, then it is most likely your wires.

The weird thing is that it is now sounding like a problem that is common to all cylinders and not just a few. This would indicate to me a single component, possibly the ignition control module. If all of the coils fail the previous test then the problem may be the ICM. You should be able to have that tested at an autoparts store.

[chad millett]

I found a guy that has a bunch of aurora parts. He sold me coil pack including the ignition module for $50. The best part is he said if that isnt it I can bring it back and try the next part. Its a good way to "trial and error" my way through this without having to buy each part.
I will put that on this morning then post the results.

I cant find anyone who has a code scanner and advance auto wont rent one out for some reason. They have a cheep actron scanner for $70 but I dont have that money right now. Im still eager to find out what she has for stored codes.

[chad millett]

so........... I changed the whole coil pack and ignition module and still no start. I pulled a couple of the front plugs to check for fuel and......now.....the plugs seemed dry. So..I squirt some fuel into the spark plug holes and turn it over and it fires a few times. Im thinking at this point that maybe its the fuel pressure is bad so I changed that.....still nothing. Im soooo confused and im starting to get frustrated !!!!!!!!

[ghutchin]

There are three things that are required for a car to run. Fuel, Compression and Spark.

Spark:
Take all 4 front plugs out and make sure that they are grounded. Now, have someone turn the car over and observe to make sure that there is consistent spark.

Fuel:
As I mentioned earlier, just because you changed the fuel pump does not guarantee that you are getting proper fuel pressure. You need to get a fuel pressure guage connected and measure the fuel pressure. After that if you still suspect a fuel problem then you need to check to make sure the injectors are firing.

Compression:
If you pass the other tests, then you should get a compression tester and check cylinder compression. All cylinders should be within 10% and should be around 165-190 psi for that car.