Just Shuts Down
Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
Just Shuts Down
Recently bought 93 40th Anniversary convertible.
When it runs it runs great.
Drove it home and kicked around the neighborhood some. Some days later had it out and after maybe a mile it just died. Pushed it into parking area and on a whim loosened the gas cap. Heard big rush of air or pressure release. Topped off tank to verify gauge reading.
Gauge is accurate.
Today, drove 4 miles brief stop(10minutes?) On way home stalled. Gas cap not tight so no rush of air. Took several tries to restart and stay running.
Showed "check gauges" and some code, I think it was CNFL Reset(?).
Ran great rest of way home, 2 or 3 miles.
Can anyone help on this?
Thanks,
JP
When it runs it runs great.
Drove it home and kicked around the neighborhood some. Some days later had it out and after maybe a mile it just died. Pushed it into parking area and on a whim loosened the gas cap. Heard big rush of air or pressure release. Topped off tank to verify gauge reading.
Gauge is accurate.
Today, drove 4 miles brief stop(10minutes?) On way home stalled. Gas cap not tight so no rush of air. Took several tries to restart and stay running.
Showed "check gauges" and some code, I think it was CNFL Reset(?).
Ran great rest of way home, 2 or 3 miles.
Can anyone help on this?
Thanks,
JP
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
Check your codes using the paper clip method. I recommend jumpering AG. Then report back.
It sounds like you have stored codes which should tell you what’s going on.
If that is not fruitful then it’s checking for what is missing (fuel or spark) when it won’t run.
It sounds like you have stored codes which should tell you what’s going on.
If that is not fruitful then it’s checking for what is missing (fuel or spark) when it won’t run.
Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
Based on previous experience, however, this seems like fuel supply interruption.
Thanks for the reply, it may be a while figuring this out as there is much going on I have to deal with other than car. Wish I had quit old cars when I sold the Caballero.
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
Don’t fret, this is quite easy (reading codes). No special tool other than a paper clip and the car may tell you *exactly* what’s wrong.
pins AG are on the obd1 connector located on the driver kick panel under the dash. I believe AG is top right and bottom left pins. You use the paper clip (or small wire) to jumper those two pins and then turn the key to “run” but don’t “start”. The dash lcd Will the readout codes.
If you need more info please google paper clip codes c4 corvette to find more including diagrams.
pins AG are on the obd1 connector located on the driver kick panel under the dash. I believe AG is top right and bottom left pins. You use the paper clip (or small wire) to jumper those two pins and then turn the key to “run” but don’t “start”. The dash lcd Will the readout codes.
If you need more info please google paper clip codes c4 corvette to find more including diagrams.
Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
Well, I find the Service Engine Light does not come on at all. Also found a piece of wire hanging from someone's previous attempt to check codes.
Could it be Service Engine light was intentionally disabled? Where would I look to see?
Could it be Service Engine light was intentionally disabled? Where would I look to see?
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
First you don’t need the SES light to read codes. Just jumper AG and the LCD (where Speedo shows) will read out all 4 module codes for you. Note the module number and each code (H is history and C is current).
The SES light (along with all of the others in the DIC (driver information center) should come on when you turn key to “run” to test that it’s working.
If you stare at the DIC when you turn key to run and it doesn’t come in at all, either the bulb blew or someone pulled it. You’d have to pull the DIC and replace the bulb.
The SES light (along with all of the others in the DIC (driver information center) should come on when you turn key to “run” to test that it’s working.
If you stare at the DIC when you turn key to run and it doesn’t come in at all, either the bulb blew or someone pulled it. You’d have to pull the DIC and replace the bulb.
Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
First you don’t need the SES light to read codes. Just jumper AG and the LCD (where Speedo shows) will read out all 4 module codes for you. Note the module number and each code (H is history and C is current).
The SES light (along with all of the others in the DIC (driver information center) should come on when you turn key to “run” to test that it’s working.
If you stare at the DIC when you turn key to run and it doesn’t come in at all, either the bulb blew or someone pulled it. You’d have to pull the DIC and replace the bulb.
The SES light (along with all of the others in the DIC (driver information center) should come on when you turn key to “run” to test that it’s working.
If you stare at the DIC when you turn key to run and it doesn’t come in at all, either the bulb blew or someone pulled it. You’d have to pull the DIC and replace the bulb.
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
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Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
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I am using the OBD1 plug in tool which I assume is the same as using paper clip. I am too old and can not see under there well enough to use a paper clip.If any thing shows it goes by so fast it can`t be read. There is a quick pass of a screen and then it just shows a little square and and something about L=100Km or something.
I just looked again and the quick screen just talks about fuel range and reserve. Very quickly changes.
I read several instructions on codes and they all say ai need to count flashes on the SES.
Could this be unplugged somewhere or is the only way to disable would be pulling bulb?
I just looked again and the quick screen just talks about fuel range and reserve. Very quickly changes.
I read several instructions on codes and they all say ai need to count flashes on the SES.
Could this be unplugged somewhere or is the only way to disable would be pulling bulb?
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
Where are you located? Maybe someone can help?
If you get the paper clip in there in the right spots it will literally read out on that LCD dash very slowly. No blinking. Blinking SES light only gives you ECM codes and potentially misses information, and since yours doesn’t work at all is useless.
You get the codes from ECM and more with jumpering AG and having it read out on the speedo/gas lcd.
Is there anyone that could come by and help get the Paper clip in the right pins?
If you get the paper clip in there in the right spots it will literally read out on that LCD dash very slowly. No blinking. Blinking SES light only gives you ECM codes and potentially misses information, and since yours doesn’t work at all is useless.
You get the codes from ECM and more with jumpering AG and having it read out on the speedo/gas lcd.
Is there anyone that could come by and help get the Paper clip in the right pins?
Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
I have not had time recently to deal with it, and it`s too hot here. I will probably not get back to it for another week. As far as someone helping me, I really don`t have anyone. How hard would it be to get the thing loose to be more accessible?
Safety Car
Joined: Jun 2010
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Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
Using an inline ignition tester I found that when it quits and won`t restart there is no spark.
At idle it will run until the fan kicks on once or twice and then quits. Cranking it shows no spark. I takes about 15 minutes of idle until it fails.
Now that I have narrowed it to spark I will do a new effort on code reading.
After cool down it will fire right up again and run for 15 or so minutes!
Last edited by JP936749!; Aug 18, 2023 at 04:23 PM.
Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
Update on 40th just quits
I have figured out that the missing component when it quits is spark. Fuel system is up to spec testing with gauge at fuel rail.
Using an inline ignition tester I found that when it quits and won`t restart there is no spark.
At idle it will run until the fan kicks on once or twice and then quits. Cranking it shows no spark. I takes about 15 minutes of idle until it fails.
Now that I have narrowed it to spark I will do a new effort on code reading.
After cool down it will fire right up again and run for 15 or so minutes!
Using an inline ignition tester I found that when it quits and won`t restart there is no spark.
At idle it will run until the fan kicks on once or twice and then quits. Cranking it shows no spark. I takes about 15 minutes of idle until it fails.
Now that I have narrowed it to spark I will do a new effort on code reading.
After cool down it will fire right up again and run for 15 or so minutes!
Changed out distributor and it seems to have cured it. Thanks for your interest.
JP
Melting Slicks
Joined: May 2005
Posts: 3,134
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From: At the St. Louis Playboy club.
Thread Starter
Cruising
Joined: Jul 2023
Posts: 12
Likes: 1
Haven`t worked on codes, troubleshot it old fashioned way. Fuel pressure gage cleared the fuel system as being guilty so went with spark tester and found that it lost spark at temperature. All my research pointed to Opti Spark. Oddly, the unit we removed showed no signs of deterioration but replacing it fixed the issue.
Now that it is cooler I may work on the SES light. Used climate-controlled garage of family member to do the distributor. He, by the way, recently took Museum delivery of new C8.
My understanding is the state of Texas does not require inspection after 25 years. They just did away with inspections except emissions in certain metro areas. My 83 Caballero was exempt but it had antique plates. I`ll probably go antique next time around on this car also.
Now that it is cooler I may work on the SES light. Used climate-controlled garage of family member to do the distributor. He, by the way, recently took Museum delivery of new C8.
My understanding is the state of Texas does not require inspection after 25 years. They just did away with inspections except emissions in certain metro areas. My 83 Caballero was exempt but it had antique plates. I`ll probably go antique next time around on this car also.