No spark help
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No spark help 85 corvette
I have a 1985 TPI. Here is what happened. I was sitting in a parking lot and the car just turned off. It may restart once in a wile for about 15 seconds but will not restart after that for about a day.
I tested the fuel pressure and its about 33 psi.
I have changed the ignition module and coil about 6 months ago along with plugs and wires and rotor.
I am thinking electric spark control. Is there a way to test it ?
Any other thoughts?
Thank you
I tested the fuel pressure and its about 33 psi.
I have changed the ignition module and coil about 6 months ago along with plugs and wires and rotor.
I am thinking electric spark control. Is there a way to test it ?
Any other thoughts?
Thank you
Last edited by paintball2000; Jan 13, 2015 at 09:13 PM. Reason: more discriptive title
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use ur phone snd video it as its so short.
rule out a fuel issue first.
if fuel psi doesnt change then id probably turn all lights off in pitch black and have somebody start it with two sets of eyes looking at the plugs wires area and see if u have an arcing short.
also you say it wont start for about a day...does it crank? or dead?
could be vats. does 85 have vats? my 85 has no vats chip on the key.
im by no means an expert at all.
Last edited by VikingTrad3r; Jan 11, 2015 at 11:01 AM.
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I think no matter how much fuel it gets I need spark to ignite it. I am pretty sure I need to fix the spark problem since I have fuel pressure. I don't think I have VATS cause my key doesn't have the chip in it and VATS is on 1986-1996 Corvette (C4). My corvette is a 1985.
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Can someone tell me if this is the correct pressure for a 1985.
Fuel Rail Pressurization:
When you first turn the key to the “on” position, the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Shraeder valve on the passenger side fuel rail near the rear of the engine and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running.test by attaching a fuel pressure gauge to the fuel rail at the shrader valve, on TPI and LT1 engines its located on the pass side fuel rail
- See more at: http://www.corvetteactioncenter.com/....DNo5Ka16.dpuf
Fuel Rail Pressurization:
When you first turn the key to the “on” position, the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Shraeder valve on the passenger side fuel rail near the rear of the engine and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running.test by attaching a fuel pressure gauge to the fuel rail at the shrader valve, on TPI and LT1 engines its located on the pass side fuel rail
- See more at: http://www.corvetteactioncenter.com/....DNo5Ka16.dpuf
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edit, I see you have just posted about gathering fuel pressure data....from your previous post I had the impression that you didnt want to bother...I apologize for misunderstanding you. Good Luck, VT.
you are ofcourse correct.
you never verified the pressure over the course of the run/stall cycle (or you have not told us if you have.
once you know you have fuel during key on, cranking, running, and during the stall....only then will u know u do not have a fuel problem.
These gauges cost 15$
Once you have this dialed in, then go for spark.
As i have stated i am no expert but i have read enough threads diagnosing these issues that i know you start with the basics, throughly documenting, the basics of fuel,spark, compression.
I hope you sort it out. From the information you have provided (i have 33psi fuel pressure)...you cannot rule out fuel as the source of your problem.
Regards,
VikingTrad3r
I think no matter how much fuel it gets I need spark to ignite it. I am pretty sure I need to fix the spark problem since I have fuel pressure. I don't think I have VATS cause my key doesn't have the chip in it and VATS is on 1986-1996 Corvette (C4). My corvette is a 1985.
you never verified the pressure over the course of the run/stall cycle (or you have not told us if you have.
once you know you have fuel during key on, cranking, running, and during the stall....only then will u know u do not have a fuel problem.
These gauges cost 15$
Once you have this dialed in, then go for spark.
As i have stated i am no expert but i have read enough threads diagnosing these issues that i know you start with the basics, throughly documenting, the basics of fuel,spark, compression.
I hope you sort it out. From the information you have provided (i have 33psi fuel pressure)...you cannot rule out fuel as the source of your problem.
Regards,
VikingTrad3r
Last edited by VikingTrad3r; Jan 11, 2015 at 04:04 PM.
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Can someone tell me if this is the correct pressure for a 1985.
Fuel Rail Pressurization:
When you first turn the key to the “on” position, the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Shraeder valve on the passenger side fuel rail near the rear of the engine and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running.test by attaching a fuel pressure gauge to the fuel rail at the shrader valve, on TPI and LT1 engines its located on the pass side fuel rail
- See more at: http://www.corvetteactioncenter.com/....DNo5Ka16.dpuf
Fuel Rail Pressurization:
When you first turn the key to the “on” position, the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Shraeder valve on the passenger side fuel rail near the rear of the engine and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running.test by attaching a fuel pressure gauge to the fuel rail at the shrader valve, on TPI and LT1 engines its located on the pass side fuel rail
- See more at: http://www.corvetteactioncenter.com/....DNo5Ka16.dpuf
You want to take pressure readings-
-when first turned on
- while cranking
- while idling
-when you stomp on it (not possible in your case as my understanding is that you cannot get it to stay running for longer than 15sec)
-DURING THE STALL
in other words, if your psi is within spec at all times, you are good to go and can move on to spark.
tip: lay the pressure gauge face in on the windshield and sit in the car. You can then read all data from sitting in the driver seat.
report back. cheers. VT
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you need to do some searching to see what the required specs are during the different phases as posted above. Specifically, during cranking as that is as far as you can get right now.
If it drops while cranking substantially (i will wait to see what the actual value is....like 10psi? 30psi? 32psi? 15psi?) Well that could be your problem right there.
I do not want to lead you down a wild goose chase as I am truly not experienced enough....but if you have very little pressure while cranking i would think thats an issue. I COULD BE WRONG.
Id suggest getting the actual cranking psi number and waiting for a more experienced senior member can chime in...like Cliff Harris or Aklim.
For whats its worth, I do not think this is going to be hard to figure out, these guys will steer you right as long as you are willing to do the tests the perscribe and report back with the answers which serve as the guidepost for the next step.
If you have access to a fsm you could go through the "engine wont start" trouble shoot.
VT.
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33psi fuel pressure is low. Should be up around 40psi. To see if you are getting spark, take the number one spark plug out and leave it plugged to the plug wire and crank the engine and see if you have a spark.
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you are not wrong, now you know you have a spark problem. you never said before that you did a spark test, if you had, i apologize for focusing in on the fuel. In ghe absence of knowing you have have no spark, we needed to rule out fuel psi. sounds like its low but probly not your root cause.
ill have a look at my 87 fsm and see if i can find a "no spark" flow chart.
meanwhile have you googled it? also somebody here will chime in.
as ive said i am no exprt but i like to follow aling because i know inevitably i will experience the dame issue.
ill have a look at my 87 fsm and see if i can find a "no spark" flow chart.
meanwhile have you googled it? also somebody here will chime in.
as ive said i am no exprt but i like to follow aling because i know inevitably i will experience the dame issue.
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i found chart c-4 in my fsm and it seems that, as long as you do have a service engine soon light with key in on position, and, as long as the ses light is not flashing, then if you have no spark, you should disconnect the est plug and then try for spark test again.
if you do have spark with the est disconnected, then you need to replace your coil.
but again....im new to this and it would be great if another experienced guy would chime in but based on what i am reading in my 87 shop manual, thats what i would do in your case.
note that if you don't have a ses light, or if it is flashing a 'code 12'. then we need to check the ecm which is a different chart and a different process.
problem is that i can't find a diagram showing you where the est wire to unplug is. i think it plugs into the distributor. like i said...im newb but trying to help you out.
other threads that may help:
https://www.corvetteforum.com/forums...-no-spark.html
https://www.corvetteforum.com/forums...-no-spark.html
from what i am reading, check for spark next with the est plug disconnected, see if you get a spark.
if you do have spark with the est disconnected, then you need to replace your coil.
but again....im new to this and it would be great if another experienced guy would chime in but based on what i am reading in my 87 shop manual, thats what i would do in your case.
note that if you don't have a ses light, or if it is flashing a 'code 12'. then we need to check the ecm which is a different chart and a different process.
problem is that i can't find a diagram showing you where the est wire to unplug is. i think it plugs into the distributor. like i said...im newb but trying to help you out.
other threads that may help:
https://www.corvetteforum.com/forums...-no-spark.html
https://www.corvetteforum.com/forums...-no-spark.html
from what i am reading, check for spark next with the est plug disconnected, see if you get a spark.
Last edited by VikingTrad3r; Jan 12, 2015 at 12:51 AM.
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The car started for about 5 seconds and died and the spark was gone anytime I cranked it after that.
I tried disconnecting the EST connector just to see what happens and still no spark.
The one thing I do notice is that when I stop cranking it, wait and then turn the key all the way back to off so I can tart it out of the ignition the motor turns just so slight, like its kicking back. I don't know if you ever tried to kick start a motorcycle and it kicks back on you. that's what it seams like.
I may go take a short video so you can see it.
I tried disconnecting the EST connector just to see what happens and still no spark.
The one thing I do notice is that when I stop cranking it, wait and then turn the key all the way back to off so I can tart it out of the ignition the motor turns just so slight, like its kicking back. I don't know if you ever tried to kick start a motorcycle and it kicks back on you. that's what it seams like.
I may go take a short video so you can see it.
Last edited by paintball2000; Jan 13, 2015 at 11:10 PM.
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From the video I would guess the starter solenoid is somehow staying engaged until you turn off the key.
The TDS (Theft Deterrent System) controls the starter solenoid through the starter enable relay, so you might have a problem in that area. I would try unplugging the starter enable relay while the ignition is on to see what happens. The relay is located next to the blue chime module behind the DIC (my system is different because I have VATS, but it's the relay with the yellow wires coming out of it - your wire color might be different):
The TDS (Theft Deterrent System) controls the starter solenoid through the starter enable relay, so you might have a problem in that area. I would try unplugging the starter enable relay while the ignition is on to see what happens. The relay is located next to the blue chime module behind the DIC (my system is different because I have VATS, but it's the relay with the yellow wires coming out of it - your wire color might be different):
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Hi paintball.
Found this thread, https://www.corvetteforum.com/forums...stump-you.html
op never verified what the issue was (make sure you always report back to let people know) but there are a few nuggets in it:
tds as it was called in 85's apparently didnt affect spark.
i get a few other nuggets:
- grab a timing light and check for spark signal this way. (i know you have seen with your eyes...but still.
- grab a noid light and check for injectors receiving pulses (ive never done this myself but this would be good to know)
- from what others have said on this thread i would suggest that you grab a multimeter and check for voltage going to the coil? and coming out of the coil? there is also a capacitor in the hei distributor that may cause issues as well.
- i would zero in on the coil and module, per one of the suggestions in this thread.
can anybody tell us how to use a multimeter and verify the voltage going to the coil?
Found this thread, https://www.corvetteforum.com/forums...stump-you.html
op never verified what the issue was (make sure you always report back to let people know) but there are a few nuggets in it:
tds as it was called in 85's apparently didnt affect spark.
i get a few other nuggets:
- grab a timing light and check for spark signal this way. (i know you have seen with your eyes...but still.
- grab a noid light and check for injectors receiving pulses (ive never done this myself but this would be good to know)
- from what others have said on this thread i would suggest that you grab a multimeter and check for voltage going to the coil? and coming out of the coil? there is also a capacitor in the hei distributor that may cause issues as well.
- i would zero in on the coil and module, per one of the suggestions in this thread.
can anybody tell us how to use a multimeter and verify the voltage going to the coil?
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another thread: http://www.corvetteactioncenter.com/...6599-no-spark-[1985-tpi-l98].html
key takeaways:
- check groundstrap under the cap
- are you getting 12v to the dist?
key takeaways:
- check groundstrap under the cap
- are you getting 12v to the dist?