I need help! totally confused. - Third Generation F-Body Message Boards

a1990camarors · 10-12-2009, 05:00 PM

ok i have a 1990 camaro rs sitting in the driveway. the car will start..then it dies within two seconds. I have spark and fuel its like the fuel injectors arent getting pulse after the cars been started. what will cause this? btw ive replaced TPS, EGR, ignition module, distributor, coil, plugs and wires, fuel injectors are good, connections are good, no security light so its not VATS, fuel pump is new, fuel filter is new. what could cause this im stumped

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HankL69 · 10-12-2009, 05:12 PM

Lack of oil pressure or a disconnected wire at the oil pressure sending unit could cause this to happen.

a1990camarors · 10-12-2009, 05:46 PM

so it could be a bad oil pump to then? the wires are good at the sending unit so unless the unit is bad itself that wont be it. Is there anyway to test the unit?

RBob · 10-12-2009, 05:55 PM

Quote:

Originally Posted by a1990camarors

so it could be a bad oil pump to then? the wires are good at the sending unit so unless the unit is bad itself that wont be it. Is there anyway to test the unit?

Don't worry about the oil pressure switch or oil pressure. It won't cause the engine to start then stall.

Since you have replaced the ignition system with no change, I'd rule that out. Unless of course it started the stalling after the ignition system was changed.

I would first check the fuel pressure. When low the car can start but won't stay running. There is a fitting on the fuel log at the rear. Easy to connect a gauge and test it.

Not sure what you have done to check the injectors. But they will cause this issue.

VATs won't do it as it won't start to begin with.

Another item to check is the 2-wire pigtail between the coil and ignition module. Sometimes the wire breaks right were it exits the coil connector. The insulation will hold it together which makes it hard to see that the wire is broken.

RBob.

Street Lethal · 10-12-2009, 06:09 PM

Quote:

Originally Posted by a1990camarors

the car will start. then it dies within two seconds. I have spark and fuel its like the fuel injectors arent getting pulse after the cars been started....

Check the connection behind the alternator (if it's loose, the engine will start, then stall immediately after). If everything is okay, then check the connections over by your coil. If good, then check for a vacuum leak between the plenum orifice and the throttle body. If everything checks out, and you already replaced the TPS, it might be your ECM....

a1990camarors · 10-12-2009, 06:23 PM

oil pressure wont do this? i thought the ecm would kill the fuel if the car dint have oil pressure?

Street Lethal · 10-12-2009, 06:28 PM

Quote:

Originally Posted by a1990camarors

oil pressure wont do this? i thought the ecm would kill the fuel if the car dint have oil pressure?

Fuel is activated when a certain RPM is realized, not oil pressure....

a1990camarors · 10-12-2009, 06:31 PM

oil pressure wont do this? i thought the ecm would kill the fuel if the car dint have oil pressure? fuel pressure is good im positive fuel injectors are good bc there new as of yesterday. all wires look to be in good shape . ecm sounds like a maybe but wouldnt it show other symptoms of bieng bad? does anyone know for sure if the oil pressure would cause this?

Maverick H1L · 10-12-2009, 09:17 PM

The oil pressure unit is for the dash and a secondary switch for the fuel pump, period. The ECM on these old cars doesn't get a signal from the OPS, so it doesn't know what the oil pressure is, nor does it care.

Everyone is forgetting the obvious possibility here... A large vacuum leak can easily cause this. He needs a noid light (or a test light between the ECM ground terminal of one injector connector and power) to actually test for an injector pulse.

a1990camarors · 10-12-2009, 10:42 PM

i dont know if its a vaccum leak. i mean some of the hoses arent in the newest condition but there isnt any holes. and i just had the intake pleum off a few days ago and all gaskets looked good. I did notice one thing thou on the same electric harness by the fuel rail i have a solid green wire with a flat yellow connector on it that isnt hooked to anything and i see so where for it to go. what is it? im starting to go crazy about this.

RBob · 10-13-2009, 09:55 AM

Quote:

Originally Posted by a1990camarors

i dont know if its a vaccum leak. i mean some of the hoses arent in the newest condition but there isnt any holes. and i just had the intake pleum off a few days ago and all gaskets looked good. I did notice one thing thou on the same electric harness by the fuel rail i have a solid green wire with a flat yellow connector on it that isnt hooked to anything and i see so where for it to go. what is it? im starting to go crazy about this.

The single green with the flat connector. Sounds like the coolant temperature sensor for the dash gauge. Check the front drivers corner of the cylinder head. IIRC, that is where the dash coolant sensor is.

For the start/stall, need to troubleshoot, IOW, check and try stuff. If you spray starter fluid in the TB during cranking does it catch and continue to run as the fluid is being added? As Maverick mentioned, a noid light on an injector will tell you a lot. Fuel pressure gauge will tell a lot.

How about spark? Is it stopping or does it continue until the engine fully stops at the stall.

When was the last time the engine ran OK? Was any work done shortly prior to it stalling? If so check that work.

RBob.

a1990camarors · 10-13-2009, 10:34 AM

i cant add starter fluid and crank only one guy lol. the car has been down for almost 5 months now. it went down because of this problem it intitally started to have a bad idle too starting and dieng right away. i thought it was a spark issue at first so i replaced distributor all the way to the plugs with new parts no luck. so then i thought fuel so i replaced the fuel pump and injectors and i have good fuel pressure right where it should be. thats why im convinced its something telling the ecm to cut fuel right after starting but i dont know what.

Street Lethal · 10-13-2009, 10:42 AM

Quote:

Originally Posted by a1990camarors

.... the car has been down for almost 5 months now. it went down because of this problem it intitally started to have a bad idle too starting and dieng right away. i thought it was a spark issue at first so i replaced distributor all the way to the plugs with new parts no luck. so then i thought fuel so i replaced the fuel pump and injectors and i have good fuel pressure right where it should be. thats why im convinced its something telling the ecm to cut fuel right after starting but i dont know what.

Crack the throttle body slightly open with the stop screw (you might need to remove the little block off plate), start the engine, and see if she holds an idle. If it does, then you have a bad IAC valve. If it doesn't, check you injector bank harness' and grounds....

a1990camarors · 10-13-2009, 11:02 AM

ill try that today i havent done the IAC yet grounds are good ive already wired brushed and checked them all lol.

a1990camarors · 10-13-2009, 11:36 AM

not the iac....ugh. im about to strap some c4 to this engine and see if i can get it to run then lol. im pretty much down to the map sensor, ecm, or broken wires

Street Lethal · 10-13-2009, 11:48 AM

It doesn't sound like fuel cutoff, it sounds like bad spark, but to be sure, you should check the injectors with a noid light while you crank the engine over. You could also pull the spark plugs out and see if they are saturated with fuel after cranking. Also, I know you replaced some items, but did you run a spark test? If not, pull the coil wire off from the distributor, stick a flat head screw driver in it nice and snug (make sure it's touching the terminal in the boot), lay it down on top of the plenum so it doesn't move, then crank the engine. You should hear a consistent spark while you crank....

a1990camarors · 10-26-2009, 07:50 PM

so finally fixed. it was a fuel issue i had 3! bad injectors that where less then 2 months old talk about annoying

Maverick H1L · 10-26-2009, 10:25 PM

Did you take it to a shop for both of the fixes? If so, I'm willing to bet they screwed you by pulling one of the fuses or something. Although, mine ran a couple weeks ago on only the driver's side bank of injectors (rewired something wrong and then fixed it), but it ran like crap. Unless, of course, they were Accel injectors...

a1990camarors · 10-27-2009, 11:35 AM

family friend who owns hes own shop did it. he dint even charge me just parts so i doubt he screwed me lol. but ya its running fine now.

entrig00 · 10-27-2009, 10:55 PM

how do you check injectors on your own? I think I'm having the same problem...