What point do injectors not pulse?
07-12-2013, 06:06 AM
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What point do injectors not pulse? On my 98 LS1;
The noid lights are telling me I have no injector pulse. I have power from harnesses and OHMs are correct on injectors. Fuel pressure gauge only shows 55lbs. Am I a couple lbs short after recent pump change or do I have another issue?
The noid lights are telling me I have no injector pulse. I have power from harnesses and OHMs are correct on injectors. Fuel pressure gauge only shows 55lbs. Am I a couple lbs short after recent pump change or do I have another issue?
07-12-2013, 06:42 AM
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That is normal. The combustion cycle is so fast that the injectors stay open all the time.
At what point this happens, I would imagine it would depend on fuel pressure and injector size.
At what point this happens, I would imagine it would depend on fuel pressure and injector size.
07-12-2013, 04:38 PM
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Ollie's statement makes no sense whatsoever.
07-13-2013, 08:23 AM
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That's what I was thinking.
I pulled my car out of storage and had no fuel pressure causing a no start. I changed the pump and filter, and drained the gas. Fresh gas, new battery, still no start. Wore the starter out, replaced it, new plugs, still nothing. Live data scan said no TPS voltage, replaced TPS and CPS, still no starts. The only measurable red flag I'm seeing is the fact that the fuel pressure is a little on the low end. I didn't wanna tear the engine apart if I don't have to. I'm wondering if the TC jumped or I have a bad cam sensor.
Does anyone have any ideas for me. I'm at a loss and have already replaced more parts than I can afford.
I pulled my car out of storage and had no fuel pressure causing a no start. I changed the pump and filter, and drained the gas. Fresh gas, new battery, still no start. Wore the starter out, replaced it, new plugs, still nothing. Live data scan said no TPS voltage, replaced TPS and CPS, still no starts. The only measurable red flag I'm seeing is the fact that the fuel pressure is a little on the low end. I didn't wanna tear the engine apart if I don't have to. I'm wondering if the TC jumped or I have a bad cam sensor.
Does anyone have any ideas for me. I'm at a loss and have already replaced more parts than I can afford.
07-13-2013, 09:35 AM
#6
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The only red flag ??
Take a look at this sensibly, changing parts like that is just mental. And cranking the engine until you destroy the starter almost defies belief.
Does the fuel pump prime when you key on ? Does the pump turn when you are cranking the engine over ( if you have a fuel pressure gauge, you will see this )
If not, then you're wasting your time doing anything more. Find out if the pump is getting power under the circumstances I described, and if not, why not.
Other easy checks, are you even getting a spark when cranking ? If not, do the coils have 12v when cranking ?
And does one side of the injector plug have 12v ? ( ecu trigger will supply a ground to trigger the injector, although this too might register as 12v when tested with a meter against ground )
You say you have access to live data....so the ecu is actually powering up ? Are you getting an rpm reading when cranking ?
Take a look at this sensibly, changing parts like that is just mental. And cranking the engine until you destroy the starter almost defies belief.
Does the fuel pump prime when you key on ? Does the pump turn when you are cranking the engine over ( if you have a fuel pressure gauge, you will see this )
If not, then you're wasting your time doing anything more. Find out if the pump is getting power under the circumstances I described, and if not, why not.
Other easy checks, are you even getting a spark when cranking ? If not, do the coils have 12v when cranking ?
And does one side of the injector plug have 12v ? ( ecu trigger will supply a ground to trigger the injector, although this too might register as 12v when tested with a meter against ground )
You say you have access to live data....so the ecu is actually powering up ? Are you getting an rpm reading when cranking ?
07-13-2013, 01:11 PM
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The only red flag ??
Take a look at this sensibly, changing parts like that is just mental. And cranking the engine until you destroy the starter almost defies belief.
Does the fuel pump prime when you key on ? Does the pump turn when you are cranking the engine over ( if you have a fuel pressure gauge, you will see this )
If not, then you're wasting your time doing anything more. Find out if the pump is getting power under the circumstances I described, and if not, why not.
Other easy checks, are you even getting a spark when cranking ? If not, do the coils have 12v when cranking ?
And does one side of the injector plug have 12v ? ( ecu trigger will supply a ground to trigger the injector, although this too might register as 12v when tested with a meter against ground )
You say you have access to live data....so the ecu is actually powering up ? Are you getting an rpm reading when cranking ?
Take a look at this sensibly, changing parts like that is just mental. And cranking the engine until you destroy the starter almost defies belief.
Does the fuel pump prime when you key on ? Does the pump turn when you are cranking the engine over ( if you have a fuel pressure gauge, you will see this )
If not, then you're wasting your time doing anything more. Find out if the pump is getting power under the circumstances I described, and if not, why not.
Other easy checks, are you even getting a spark when cranking ? If not, do the coils have 12v when cranking ?
And does one side of the injector plug have 12v ? ( ecu trigger will supply a ground to trigger the injector, although this too might register as 12v when tested with a meter against ground )
You say you have access to live data....so the ecu is actually powering up ? Are you getting an rpm reading when cranking ?
The pump primes and runs. Spark is good. Coils and injector plugs have voltage. I checked all this before I bought anything. ECU is good, and yes there is RPM reading.
Like I said, everything that I know of that can be externally measured seems fine. Was just wondering if the 55lbs was too low to pulse the injectors.
Also that starter had 60-80k on it and had been sitting in storage for 2 years. It didn't take much for it to die.
I think I've done everything in a pretty respectable order. I just don't want to open the motor looking for the problem unless I have to. I was kinda hoping someone would tell me I needed a few more lbs of fuel pressure.
Also, the car would start on starting fluid before I changed the fuel pump. After I changed the pump it no longer would. It back fired out of the air box a couple times, now it just cranks but won't even attempt to start.
Last edited by 1998Z28LOADED; 07-13-2013 at 01:16 PM.
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07-13-2013, 02:02 PM
#8
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55psi fuel pressure is more than enough to run the engine.
If you have confirmed a good strong spark at all 8 plugs when cranking., then that would imply that crank/cam signal is good.
However, it's hard to imagine how you would have that spark, and no trigger to the injectors. Although I would say that noid lights are always 100% reliable.
If you had a multimeter with duty cycle, pulse width or maybe frequency, it might do no harm to stick it across the injector wires and see if it sees any signal when cranking.
Are the spark plugs wet or dry ?
Whilst a pain, can you remove the fuel rail/injectors and actually visually check for fuel being injected ? Or even unbolt the intake and lift it up a few inches to carry out a visual.
Really though, if it has spark, and is getting some fuel, you should see some sort of sign of attempting to fire.
If you have confirmed a good strong spark at all 8 plugs when cranking., then that would imply that crank/cam signal is good.
However, it's hard to imagine how you would have that spark, and no trigger to the injectors. Although I would say that noid lights are always 100% reliable.
If you had a multimeter with duty cycle, pulse width or maybe frequency, it might do no harm to stick it across the injector wires and see if it sees any signal when cranking.
Are the spark plugs wet or dry ?
Whilst a pain, can you remove the fuel rail/injectors and actually visually check for fuel being injected ? Or even unbolt the intake and lift it up a few inches to carry out a visual.
Really though, if it has spark, and is getting some fuel, you should see some sort of sign of attempting to fire.
07-13-2013, 07:17 PM
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Fuel gets to the plugs. I changed them after I had washed them down pretty good with fuel and starting fluid. Ill try checking the injector wires while cranking and see what I have. I'm completely confused why its not starting. I suppose the next step is popping off the front cover and seeing if I am still dot to dot?
I don't see what could have went wrong between pulling it out of storage and it fired instantly on starting fluid and towing it home and installing the pump.
I don't see what could have went wrong between pulling it out of storage and it fired instantly on starting fluid and towing it home and installing the pump.
07-14-2013, 04:04 AM
#10
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If the plugs are soaked, then replace them, but you seem to have done that already.
I would find it impossible to believe the chain has jumped, and would also think the ecu would report some sort of crank/cam sync issue if it did.
If you have good spark at all 8 cylinders, and firing at the correct time, you have fuel being injected and the engine has air, then there is no reason for it not to make some sort of attempt to start.
Again, I'm not saying injector signal or wires here. I have seen cases where cars have sat for a long time and the injectors have simply stopped working. It is bizarre, but has happened. It's a mechanical problem, not electrical, hence asking for a visual confirmation that fuel is spraying.
I guess a compression test would also do no harm, but the problem is very unlikely to be with the engine itself.
I would be interrogating the ecu to ensure all signals it is supposed to be receiving are sensible
I would find it impossible to believe the chain has jumped, and would also think the ecu would report some sort of crank/cam sync issue if it did.
If you have good spark at all 8 cylinders, and firing at the correct time, you have fuel being injected and the engine has air, then there is no reason for it not to make some sort of attempt to start.
Again, I'm not saying injector signal or wires here. I have seen cases where cars have sat for a long time and the injectors have simply stopped working. It is bizarre, but has happened. It's a mechanical problem, not electrical, hence asking for a visual confirmation that fuel is spraying.
I guess a compression test would also do no harm, but the problem is very unlikely to be with the engine itself.
I would be interrogating the ecu to ensure all signals it is supposed to be receiving are sensible
