Yeah yeah, it's not a Vette...but I DO have a Vette so you have to help me anyway! :D I posted this over at camaroz28.com, but this place is usually quite a bit bussier so I post here also.

It ran fine the day before yesterday, but I went to start it today and it won't start.
I turn the key and the starter works but the engine doesn't fire. I put some gas in it cause it was VERY low, but still the same problem. Tried some starting fluid and still no go. Held the gas to the floor and held the ignition for a few seconds and it TRIED to fire, but did not come to life. (don't know if it was igniting fuel or starting fluid though)
What could be the problem? When I turn the key to accessory I can hear the fuel pump. I also have the VATS bypass on the car, though I don't think this is a VATS related problem because if I remember correctly, VATS shuts off the starter (as well as the injectors and ignition).

Could there maybe be air in the fuel lines from trying to start the car with very little gas in it? I remember I had a problem with my '87 Vette about a year or so ago and I had to take it to a shop cause I couldn't figure it out. Turns out it was a bad "ignition module." Where is the ignition module located on my IROC?

I need to get this car running before it rains! (I do not want to ride in the rain!)

 

Need to figure out if its a fuel or spark problem. If its fuel tho it woulda probably fired up on the start fluid.

 

Does your tach move up while cranking? If not I am betting there is no spark there. I had a similar prob recently. What year are we working on?

If no spark ignition module or ECM fuse would be my starting place. The module should be in the distributor if it is the big distributor and who knows if it isn't. You should be able to change the module with simple hand tools.

Just a guess,

v


[Modified by Hugh Jass, 6:18 PM 6/10/2002]


[Modified by 90_roadster, 6:19 PM 6/10/2002]

 

What's up with that?

 

Is there spark? Use your timing light or a spare spark plug connected to one of your plug wires. Are the injectors being pulsed? Use a voltmeter or a small 12v light bulb across on of the unplugged injector harness plug. Check your injector fuses. If the tach doesn't read when cranking, then the ignition module is probably defective. Some auto parts places will test them. Is there 12v on the batt wire on the distributor? If the ignition module checks ok and the tach isn't working, then I would change the pickup coil. Good luck.

 

Ok, first off it's a 1990 IROC...oops. :o

Well we got it to start. We jumped the battery to another car and kept trying to start it and it finally tried to sputter so I got on the gas double quick. Then it started. Once it's running it runs fine. I turned it off and turned it on again and it started up ok. We went to start it this morning and it did start though it was reluctant.

When it wasnt starting, we did use a timing light to confirm spark. If it won't start again, I'll try that valve on the fuel rail. What do you think could be making it not want to start? Could this still be the ignition module?

Very confusing stuff :confused:

 

Did you check the spark plug gap? I had a car go from running fine to running really badly when my plug gap got too wide. I could not believe out quickly it went from good to bad in about 1 week. I thought there was something seriously wrong. The gaps were really wide.

Check for spark going to the plugs also. If starter fluid does not help it is most likely electrial.

 

Since you were able to jump it, sounds like the battery has a weak or dead cell. And since it runs ok once started, the alternator is probably ok. Have the battery load tested. Also, hook up an DVM in series with the battery and check for any drains with the engine off.

 

DOH! It was running fine, but now it's doing this again!! :mad:

only codes are 32 and 46 (EGR and VATS) Hmmm, could it still be a VATS problem even though the fuel pump is working?

I've disconnected the battery to clear the codes in the ECU. I'm going out right now to test for fuel pressure, spark, and injector pulse.

 

Going to test injectors again (on the old volt meter, they're only showing 1/2 volt ac [don't ask. I wasn't working the meter...] I'm going to try it with my new meter). But as it stands right now, we have spark and fuel. I do not understand. There seems to be no reason why it shouldn't start :confused: I also tried to check codes after all of this and it was clear...not sure if it would have even been able to set any codes yet...

Man, this is getting real old. Any ideas anyone??

 

Ok, I'm getting ~1v DC on the injectors. I'm getting spark and the fuel rail is pressurizing. It ran just fine the day before yesterday and started with no problem.

Is that the correct voltage to the injectors?
How MUCH gas should come out of the rail when I test it, should it dribble out or should it be a high pressure spray that comes out??
Could this be a problem with the fuel pressure regulator?
Is there any way that this could be a problem with the VATS? (I already know it can't be because all of the things that VATS controls are working...but thought I'd ask just incase)


[Modified by A, 2:21 PM 6/15/2002]

 

The modual can do wierd things,Its temp.sensitive. Id change it just to eleminate the possibilty. :chevy

 

VATS will not allow the starter to crank or the injectors to pulse. 1 volt on the injectors is inadequite, but a voltmeter cannot respond to the short duration pulse on the injector coils and will read the average which is very low. Put a small 12v light bulb on one of the injector plugs and see if it is pulsing. Check your injector fuses. If the fuses are good and the pulse non existant but the engine cranks, then I would suspect a defective ECM.

 

I'm going to put a gauge on the fuel rail as soon as I can get my hands on one. It does not seem like very high pressure that the fuel is coming out of that valve... perhaps this would indicate a failing fuel pump? If the rail was not pressurized enough then would that keep the injectors from firing?

Also, I re-confirmed that I DO have spark by attaching a spare spark plug to one of the wires and watching it spark against the exhaust manifold. Which really makes me wonder why it won't start on starting fluid :confused: Maybe it's just not getting down in there through all the TPI ducting or something... perhaps the ignition module is going bad and it is not sparking at the correct time? I hear that that ignition module controlls the tach, well my tach is WOEFULLY inacurate; the needle is pegged when the engine is actually only turning maybe 2500 RPM's...but the needle does move when I attempt to start the engine... don't know if that is useful info or not...

 

:eek: :eek: :confused: :confused: :confused: good question!

 

Put your timing light on it and determine if the spark is occurring at the right time. Your fuel pressure gauge will also tell you if the fuel pump is supplying fuel. Starter fluid may not work because the spark timing is incorrect. Another cheap way to tell if your injectors are working is to smell your exhaust while someone cranks the engine. You should smell raw fuel.

 

Ok, here's the progress:

I borrowed a fuel pressure gauge and an ignition module from Romeo. Went out and worked on the car this morning and checked the fuel pressure and it was perfect...so that eliminated alot of possibilities, next task was to change the ignition module. Well I got the cap off and it and the rotor were VERY worn!! I decided to go buy a new cap & rotor before I did anything else. I put on the new cap & rotor and she started right up beautifully... BUT now she won't stay running and runs like crap. I'm showing a code 33 which is the MAP sensor, correct??

I just disconnected the battery to clear the computer in hopes that maybe that'll fix the problem... not likely though. Never showed a code 33 before though.

Any new ideas fellas? She STARTS great now, just won't run worth a damn and stalls :)