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NO START? got fuel and spark?

10K views 21 replies 4 participants last post by  FREIGHTLINER00 
#1 ·
i purchased a 94' ss that has been sitiing for about 4 years, i got the car not running and with a bad fuel pump well, i dropped tank and changed out the pump and put new fuel in it as tank was completely empty i added 10 gallons of 93 octane with a guage on the rail i hear the pump come on and i have correct fuel pressure.

so i goto crank and it just turns over and wont turn on?

i pulled number 1 spark plug wire off to check for spark at the plug and i have spark and good spark at that. but it seems to be that the INJECTORS ARE NOT FIRING?

i checked the under hood fuse box and both fuel injection fuses are good as well as the EMI fuse what gives?


so i went to the auto parts store and bought a can of starting fluid to see if she will fire with help and sure enough she turn right on and quickly so i am stuck at the injectors not opening and firing fuel? how can i get around this problem and get her fixed has anyone else encountered this problem any help would be great i would love to get her fired up and stsrt driving it.

any help would be greatly appreciated.
 
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#2 ·
and i am getting a redish orange type of spark either way the car turns over with the spark it has an the either so it should do the same thing with the fuel thats being sprayed with the same faint spark.


i dont have a way right now to check injector pulse but will try tomorrow.

why wont this thing start.
 
#3 ·
Prone failure point for the injectors is the harness, sometimes the feed to them breaks with in the harness, have you checked for voltage at one of the injectors with a meter? This would be a way to tell for sure if you have power. Pick up a node light at autozone they are cheap and see if it is firing after that.
 
#5 ·
so should i check the voltage with a multi meter? or should i buy the noid lite just to see if it flashes? will it serve the same pupose?

if it is the wire issue what would i do in order to go around it power up the injectors with a new wire from the under hood fuse box? where is it that they are prone to breaking the wire?by what part of the harness in the rear of the pass head? or driver head? do all the injectors get powered by the same wire and then just get a signal from pcm thru other wire to spray, i am almost certaint the injectors arent spraying fuel? why else would it start with starting fluid and not the same gas in the system and it has correct fuel pressure.
 
#7 ·
so if the spark is orange/red and is starting off of starting fluid then how do you explain that?

the same spark that is igniting with the starting fluid should start with the fuel or gas in the system unless the injectors arent spraying in order for the fuel to reach the cylinder and combust with the same reddish/orange spark.

i dont know if you get were i am coming from?

Even if the spark is not optimal, it does fire with starting fluid, don't worry about right now, get it running on it's own then deal with that.

With a multimeter you can check the voltage, the noid light is going to tell you it is firing, obivously, as the meter isn't fast enough to read it.

Power is fed to all the injectors pretty much off the same wire, in some areas it is known to get brittle and can break down, the PCM provides the ground to fire each injector individually.

If you have power and the noid light doesn't flash that would indicate the PCM isn't saying to fire, I am pretty sure that the spark and injectors are off of the same resolution in the opti, but can't remember, could be a crappy opti or connection as well.
 
#6 ·
so if the spark is orange/red and is starting off of starting fluid then how do you explain that?

the same spark that is igniting with the starting fluid should start with the fuel or gas in the system unless the injectors arent spraying in order for the fuel to reach the cylinder and combust with the same reddish/orange spark.

i dont know if you get were i am coming from?
 
#8 ·
are you for real so this could still be an opti problem aw man? but when i keep it on with the starting fluid the car will stay running as long as i spray.

which wire is supposed to be the one to check voltage to as there are 2 wires going to each injector? also how much voltage should be going to each injetor?
 
#11 ·
Use a test light and unplug an injector. figure out which terminal has ignition hot. Then take the test light and put the ground lug on the battery hot terminal. probe the other pin in the injector connector while someone cranks. if the test light blinks the pcm is switching the injector on and off. If it doesn't blink, then there's a troubleshooting guide for just that. Let me find the link. BRB.

EDIT: In the stickies, follow the link and scroll down till you get to the point your at which is no fuel pulse diagnostics. Just read through till you find it.
http://www.mainstreamtopics.com/forums/topic/78-lt1-no-start-diagnostic/
Chris
do As Chris stated above, he maybe able to tell you for sure or not, but for some reason I thought that the injector firing worked of a different resolution signal from the opti. I could be all wet though.
 
#10 · (Edited)
Use a test light and unplug an injector. figure out which terminal has ignition hot. Then take the test light and put the ground lug on the battery hot terminal. probe the other pin in the injector connector while someone cranks. if the test light blinks the pcm is switching the injector on and off. If it doesn't blink, then there's a troubleshooting guide for just that. Let me find the link. BRB.

EDIT: In the stickies, follow the link and scroll down till you get to the point your at which is no fuel pulse diagnostics. Just read through till you find it.
http://www.mainstreamtopics.com/forums/topic/78-lt1-no-start-diagnostic/
Chris
 
#12 ·
well i am getting no injector pulse, i put a test light to the pink wire with ignition on and it has power all of the time even when turning over the engine, the other wire i powered the test light and used the tip as if i was checking for ground and trying to turn over the engine or with the ignition on it doesnt turn on no flicker at all.

does the optical sensor in the opti control the injector pulse?
 
#13 ·
well i started poulling apart the front of the engine to get to the opti and noticed it will need a new water pump as the one that was on there appears to have a large stain around the weep hole is ig it was dripping from there and the opti cap is stained as well, i took the opti off and opened it up i noticed the tip of the rotor looks as if its about to break off not the outside part of the rotor but the middle part of it where it makes contact with the brush button on the inside center of the cap. i also noted that were that contact ball is supposed to be in the cap in the center it is MISSING? could this be why it has a reddish orange spark and not a blue colored spark?

everything else inside seems to be intact i am trying to get a known good working opti to try to see if i could troubleshoot.

any info on this would be great so does the optical sensor contro linjector pulse?
 
#14 · (Edited)
Yes it does. the high resolution controls the spark IIRC and the low res i responsible for determining engine position for fuel. There is a test to determine if the opti is "reporting" while cranking on both circuits since 12 volts is reference, depending on the reporting of the sensor, ac current is generated. I have the info. let me find it. A related note is you might want to verify output of the vats system if it hasn't been bypassed yet. It might be a worthwhile "troubleshooting" step. BRB

Edit. Its in the same section in the link i posted under opti t/s.

Chris.
 
#15 ·
allrite went outside checked everything i am getting 6V at the opti plug, and i am getting the hot wire as well as the ground wire?

so i threw another back opti plate i have here from a known working car that i was running a delteq on but i modified the cap and shaved the plug wire nubs off it as well as the coil wire nub the rotor is still inside but has both ends cutoff so the rotor piece that is in there right now is just to hold the center disk down well this was working on my car with the delteq as it was only providing the signal from the optical sensor for reference so why wont this thin give me injector pulse?
 
#18 · (Edited)
The injectors are cycled by the pcm. The 11.9 your getting is a drop across the ground that is open because the injector driver is not grounding the circuit.
The AC scale i was referring to was on the opti connector itself,between its pins while cranking, not on the injector connector.

http://shbox.com/1/95_ign_system_schematic.jpg


Chris
 

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#20 ·
welli got her to turn on finally i had to pull up on the injectors to see physically if they were spraying 2 of them werent i pulled them off cleaned them now they all spray i presented the injector rail down onto the manifold and turned over car it ran and reved perfect. now i have to assemble the fronbt of the engine.
 
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