97 aurora wont start

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

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.

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?

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.

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

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?

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.

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.

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.

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 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.

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.

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.

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 :banghead: !!!!!!!!

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.

ok.... I bought a OBD2 reader and got a code p0107 MAP sensor and p0107 pending.....
Where is the map sensor located on a 97 aurora?
Could this cause a no start issue?

MAP can definitely cause the problem. The sensor is located on top of the intake directly past the throttle plate. It is rectangular is plugs into the intake. Very easy to remove. The only thing is that your car, I think has a Mass air flow as well, so I would think it could depend on that as well if the MAP was acting up.

Before replacing it, use the scanner to clear your codes. then try to start the car and scan for codes again to make sure that it comes up again.

ok I changed the map sensor and still no start. The codes are cleared and they did not return.
I have narrowed the problem down to the injectors not firing now.....
I pulled off the air intake before the mass air flow sensor....had an assistant crank the engine while I sprayed starting fluid into the intake and it runs. It stalls as soon as it burns off the fuel. It seemed to run good also. There is 12 volts going to one wire of the injectors and something on the other side but it doesnt change while cranking the engine.
What can cause the injectors to not squirt? I checked the fuse and that is good. :shakehead

ok it started. While I was trying to check for fuel I found some water in it. I drained all the gas out and put in some 91 octane with water remover also. It started! It runs rough just like it did before the no start issue......so I had a couple of problems and I have fixed one. Now I need to see why its runs so poorly..... the only codes are for random multiple cylinder misfire.
I want to check the fuel pressure first because it doesnt seem to have much when I press the release valve. Im going to have to buy a guage because I cant find one to borrow.:headshake

You can get them cheaply at Harbour Freight <$30 I think. Autozone and Advance auto should also have them for $40.

what is the correct fuel pressure for the 97 aurora 4.0?
I bought a guage. I will check the pressure tomorrow.

First turn the key forward for a few seconds, but do not start the car. Turn the key to off. This will prime the fuel pump. Do this twice and the fuel pressure should hit a maximum which should be at least 40 psi. Now look at the gauge and watch it for a few minutes and see if it holds pressure. If the pressure starts bleeding off you either have a leaky injector or the check valve in the fuel pump is failing. Since you already replaced the fuel pump this would suggest that you have a leaky injector.

Next, start the car. At idle it should be around 39-41 psi. At idle, if you pull the vacuum line to the FPR the pressure should increase by at least 5 psi to ~45 psi.

Finally its all fixed! Its much easier to diagnose a car that runs.
So it had two issues.....First it had a lot of water in the gas because the lock ring for the fuel pump was rusted so bad the fuel pump was popping out of the tank. The day the car died altogether it was raining and it kept getting worse because of all the water entering the fuel. When I was checking for fuel volume/flow I discovered the water. So that got it running. It wasnt firing on all cylinders. I pulled one plug wire at a time and put a spark plug in the end and grounded it out....then started the car. The number six cylinder was only sparking once and a while. So I changed that coil and it runs great!:grinyes: Im sure the cylinder that shared the same coil was misfiring too but I didnt check first.
Im so glad!
Now I think its time to get rid of this car before it has any more issues!
Its a blast to drive but too expensive to work on!
Thanks for all the guidance along the way!
Chad

Good to hear.

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.
It sounds like the timing is off, Might need timingbelt:confused:

...