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1990 cranks but won't start

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Old 07-06-2018, 12:30 AM
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Maldini
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Default 1990 cranks but won't start

Need a little help, as I am not sure what to do next. My 1990 will crank, but has no signs of catching and/or running. The car recently returned from a 20-year visit in Italy, and from what I know, the car hasn't been started in 6 or so years (ran beautifully before that). I'll list what I've done to this point - some might seem irrelevant or un-necessary, but i'll list it all of so you have the full run down. Car has 17,000 miles, and is a 6-speed.

1. Removed all spark plugs. Checked for wear - all looked good and gaps were within spec.
2. While plugs were out, I shot some fogging oil to prep the cylinders for their first run.
3. Removed the sending unit, did a physical inspection - all looked good.
4. Pulled all the old fuel, and blew out the line between the sending unit and the fuel filter with very minimal psi. Also cleaned the tank, and pumped in fresh 91 octane.
5. Installed a brand new AC Delco fuel filter (with the flow arrow pointing towards the front of the car).
6. Installed a new air pump, belt tensioner, and serpentine belt.

As I mentioned, the engine will crank and sounds strong, but has no sign of starting. My troubleshooting to this point has been:
1. Inspected #1 spark plug after multiple attempts to crank. No gas odor, and was not wet.
2. Tested spark on #1 - looked good and strong.
3. I can hear the fuel pump prime, and I get ~40ish psi at the fuel rail with the key in the on position.
4. While attempting to crank, the needle will jump to ~45ish psi (maybe a bit more)

Other points to mention;
1. "Security" light on the dash will blink, and then go off when the key is inserted
2. Car has an aftermarket Alpine alarm system. I haven't armed or disarmed the car since I got it, or messed around with it at all (key fob batteries are dead)...
3. I've noticed my oil pressure jump/climb as I attempt to start
4. I don't believe the RPM needle moves at all while attempting to start.

I'm sure you're at the same conclusion I am by now, and are leaning towards the injectors, and whether or not they're firing. I'll need some help in this area, as I haven't dug this deep before. I've read threads on a bad ICM can causeto this, bad injectors, but I would like your thoughts.

Thanks so much.
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Old 07-06-2018, 08:02 AM
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JimLentz
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Use a noid light to check that the injectors are being pulsed.
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Old 07-06-2018, 12:39 PM
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Thanks. Iíll grab a kit on my way home and test tonight. I was reading some older posts, and suggestions were made to test ohms on each injector, so Iíll do this as well.
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Old 07-06-2018, 01:21 PM
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Originally Posted by Maldini View Post
Thanks. Iíll grab a kit on my way home and test tonight. I was reading some older posts, and suggestions were made to test ohms on each injector, so Iíll do this as well.
https://www.autozone.com/test-scan-a...set/948078_0_0
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Old 07-06-2018, 01:28 PM
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Sounds like fuel is not getting to the injectors, could be the vats, but you said the security light flashes and then goes off when you put the key in, that's the way my 92 works, I think that is how they are supposed to work, there are some codes you can look at, if there are any, one of the ways is , with the key on, hold the up and down arrows at the same time, when the screen goes to double zeros press the center fan button and the code will show, there is another way jumping the diagnostics plug under the dash, google c4 engine codes and both these videos will show up I think.
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Old 07-06-2018, 01:38 PM
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Originally Posted by gemsvette View Post
Sounds like fuel is not getting to the injectors, could be the vats, but you said the security light flashes and then goes off when you put the key in, that's the way my 92 works, I think that is how they are supposed to work, there are some codes you can look at, if there are any, one of the ways is , with the key on, hold the up and down arrows at the same time, when the screen goes to double zeros press the center fan button and the code will show, there is another way jumping the diagnostics plug under the dash, google c4 engine codes and both these videos will show up I think.
I doubt it. To many, when a problem occurs, VATS is blamed and removed. If it was a VATS problem, I don't think it will crank even. Try this. Tape up the VATS chip and try to crank it. After that, remove the tape and try cranking. It probably won't let you crank for 2 or 3 minutes or so after a failed attempt,
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Old 07-06-2018, 01:48 PM
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Originally Posted by Maldini View Post
Need a little help, as I am not sure what to do next. My 1990 will crank, but has no signs of catching and/or running. The car recently returned from a 20-year visit in Italy, and from what I know, the car hasn't been started in 6 or so years (ran beautifully before that). I'll list what I've done to this point - some might seem irrelevant or un-necessary, but i'll list it all of so you have the full run down. Car has 17,000 miles, and is a 6-speed.

1. Removed all spark plugs. Checked for wear - all looked good and gaps were within spec.
2. While plugs were out, I shot some fogging oil to prep the cylinders for their first run.
3. Removed the sending unit, did a physical inspection - all looked good.
4. Pulled all the old fuel, and blew out the line between the sending unit and the fuel filter with very minimal psi. Also cleaned the tank, and pumped in fresh 91 octane.
5. Installed a brand new AC Delco fuel filter (with the flow arrow pointing towards the front of the car).
6. Installed a new air pump, belt tensioner, and serpentine belt.

As I mentioned, the engine will crank and sounds strong, but has no sign of starting. My troubleshooting to this point has been:
1. Inspected #1 spark plug after multiple attempts to crank. No gas odor, and was not wet.
2. Tested spark on #1 - looked good and strong.
3. I can hear the fuel pump prime, and I get ~40ish psi at the fuel rail with the key in the on position.
4. While attempting to crank, the needle will jump to ~45ish psi (maybe a bit more)

Other points to mention;
1. "Security" light on the dash will blink, and then go off when the key is inserted
2. Car has an aftermarket Alpine alarm system. I haven't armed or disarmed the car since I got it, or messed around with it at all (key fob batteries are dead)...
3. I've noticed my oil pressure jump/climb as I attempt to start
4. I don't believe the RPM needle moves at all while attempting to start.

I'm sure you're at the same conclusion I am by now, and are leaning towards the injectors, and whether or not they're firing. I'll need some help in this area, as I haven't dug this deep before. I've read threads on a bad ICM can causeto this, bad injectors, but I would like your thoughts.

Thanks so much.
If the tach doesn't "move" during crank I'd lean towards a bad crank sensor but since you said you HAVE spark that's not the problem (no crank signal equals no injector pulse or spark)...just spray some propane or Brakleen into the PCV or brake booster line while cranking and it seems like it wants to start or starts you have a fuel delivery issue...fuel pump or injectors...QUICK TEST !!

Last edited by rwobs777; 07-06-2018 at 01:50 PM.
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Old 07-06-2018, 01:50 PM
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Originally Posted by rwobs777 View Post
If the tach doesn't "move" during crank I'd lean towards a bad crank sensor but since you said you HAVE spark that's not the problem (no crank signal equals no injector pulse or spark)...just spray some propane or Brakleen into the PCV or brake booster line and it seems like it wants to start you have a fuel delivery issue...fuel pump or injectors !!
I don't believe the 90 has a crank sensor. I agree with the spraying of fuel in. Maybe starting fluid is also an option if you don't get carried away?
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Old 07-06-2018, 02:27 PM
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Originally Posted by aklim View Post
I don't believe the 90 has a crank sensor. I agree with the spraying of fuel in. Maybe starting fluid is also an option if you don't get carried away?
I'll grab a can of starter fluid as well on my way home. When you say to not get carried away, what do you mean? Don't spray too much in the intake?
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Old 07-06-2018, 02:31 PM
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Originally Posted by Maldini View Post
I'll grab a can of starter fluid as well on my way home. When you say to not get carried away, what do you mean? Don't spray too much in the intake?
Correct. Some is good, don't blast too much
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Old 07-06-2018, 03:23 PM
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Originally Posted by aklim View Post
I don't believe the 90 has a crank sensor. I agree with the spraying of fuel in. Maybe starting fluid is also an option if you don't get carried away?
I think you're right...I just looked at the wiring diagrams at BBBind.com for 1990...didn't see one....My Bad !!...OP, Sans the CKP...do the C4's have a hand crank in the front of the engine ??...LOL...only kidding !!
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Old 07-06-2018, 03:24 PM
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Originally Posted by Maldini View Post
I'll grab a can of starter fluid as well on my way home. When you say to not get carried away, what do you mean? Don't spray too much in the intake?
Just a couple of squits and crank 'er up...that stuff is pretty volatile...be careful !!
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Old 07-06-2018, 05:48 PM
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Ok so I checked resistance on all injectors, and all are between 16-16.2 ohms. Using a noid light on two separate injectors I get no light when the key is in the on position.

For what it's worth I checked every fuse, and all are ok. With the key in the on position I checked voltage between the two terminals for each of the two injector circuits (on the fuse box), and I get right around 12V for each.

Also pulled codes, and there are none to be had, and none in memory (though I've only had power to the car for the last week or so)

Used a couple shots of starter fluid and almost immediately the engine showed signs of starting. I didn't go any further since I heard what I was expecting.

So now the question becomes why I don't have power to the injectors. What should my next step be?
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Old 07-06-2018, 06:18 PM
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Originally Posted by Maldini View Post
Ok so I checked resistance on all injectors, and all are between 16-16.2 ohms. Using a noid light on two separate injectors I get no light when the key is in the on position.

For what it's worth I checked every fuse, and all are ok. With the key in the on position I checked voltage between the two terminals for each of the two injector circuits (on the fuse box), and I get right around 12V for each.

Also pulled codes, and there are none to be had, and none in memory (though I've only had power to the car for the last week or so)

Used a couple shots of starter fluid and almost immediately the engine showed signs of starting. I didn't go any further since I heard what I was expecting.

So now the question becomes why I don't have power to the injectors. What should my next step be?
I'm not sure on a 1990 if the injector control wire is ground side switched...I know my '01 is...can someone chime in if you know ??...if it is you'll have 12 volts on the feed side...you're good.....if the control wire is ground side switched (the PCM grounds the control wire to fire the injector when the key in ON) and you were to connect an INCANDESCENT test light or "computer safe light to battery POSITIVE by back probing the control wire with a t-pin and touch the tip to the control wire the light will light if the control wire is good to the PCM...if not you have an open somewhere..or PCM driver is bad....you normally use the noid light while the engine is running !!

You can watch this instead of me blabbering away...LOL !!!


Last edited by rwobs777; 07-06-2018 at 06:28 PM.
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Old 07-06-2018, 11:36 PM
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Originally Posted by Maldini View Post
Ok so I checked resistance on all injectors, and all are between 16-16.2 ohms. Using a noid light on two separate injectors I get no light when the key is in the on position. For what it's worth I checked every fuse, and all are ok. With the key in the on position I checked voltage between the two terminals for each of the two injector circuits (on the fuse box), and I get right around 12V for each.

Also pulled codes, and there are none to be had, and none in memory (though I've only had power to the car for the last week or so)

Used a couple shots of starter fluid and almost immediately the engine showed signs of starting. I didn't go any further since I heard what I was expecting.

So now the question becomes why I don't have power to the injectors. What should my next step be?
Did you crank it when you were having the noid light hooked up to the injector harness? IIRC, it is hot and the ECM grounds it when it wants to fire. When the pulse is about 1-2 milliseconds, the only easy way is to use the noid light. Sounds like it isn't grounding when it should, assuming you were having the noid light attached when cranking.

The ECM is pretty crude so codes don't always tell the story.

Did it start and keep running?


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Old 07-07-2018, 01:07 AM
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I did not attempt to crank when I had the noid light connected. I can try tomorrow though.

I only squirted a couple shots of starter fluid, and so it didnít ďrunĒ for very long. The engine sounded similar to the last few seconds before you would ran out of gas... if that makes sense.
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Old 07-07-2018, 10:16 AM
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Originally Posted by Maldini View Post
I did not attempt to crank when I had the noid light connected. I can try tomorrow though.

I only squirted a couple shots of starter fluid, and so it didnít ďrunĒ for very long. The engine sounded similar to the last few seconds before you would ran out of gas... if that makes sense.
.

From South Main Auto on a no start 1989 Corvette...heís using noid light and brake clean..check it out !!
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Old 07-07-2018, 10:24 AM
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Originally Posted by Maldini View Post
I did not attempt to crank when I had the noid light connected. I can try tomorrow though.

I only squirted a couple shots of starter fluid, and so it didnít ďrunĒ for very long. The engine sounded similar to the last few seconds before you would ran out of gas... if that makes sense.
That is about the way the noid light works. You crank and you see injector pulses or not.

Yes, that means that something isn't getting fuel there and the "fuel" you put in has run out.
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Old 07-07-2018, 10:44 AM
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I misunderstood then, I thought I read somewhere there is always power to the injectors when the key is on.

Anyway i I didnít have time just now to test all 8, so I put the noid light on the #1 injector and it was pulsing as the engine was cranking.
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Old 07-07-2018, 10:56 AM
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Originally Posted by Maldini View Post
I misunderstood then, I thought I read somewhere there is always power to the injectors when the key is on.

Anyway i I didnít have time just now to test all 8, so I put the noid light on the #1 injector and it was pulsing as the engine was cranking.
I'd do #2 just to make sure BOTH banks are firing. If so, you have injector pulse. Sounds like the signal is being sent to fire the injectors. Do you have fuel pressure?
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