hello i am new to LT1s , last week i purchased a 1995 camaro z28 with 95k miles automatic transmission . it fired up multiple times and i even drove it home , a 30 min trip. let it sit in my yard for 3 days and after that it didnt want to start. i cleaned maf,iac,tb, and fuel filter. i got a psi readings of old pump (magicaly started)while at idle it was at 30 psi. so i easily thought okay then the FP is the culprit. today in the morning i changed out the old fp with a new one. i primed it 4-5 times and it fired back up at first rip. after 3-5 mins idling it shut off and only cranks again. i sprayed some starter fluid and no difference it pops and farts but does not fire up ....im completely lost at this point

 

Have you scanned for codes?

Did you recheck the fuel pressure?

Have you checked for spark at the plugs?

 

yeah i scanned codes and i only got P0420 which is regarding the bank 1 o2 sensor or cat. i will re check the fuel pressure tomorrow morning and post a video of results. and no i have not checked for spark at the plugs...the best way to check is to unplug the wire from the spark plug and crank and look for a spark right ?

 

P0420 is an OBD-2 code for low cat converter efficiency, bank 1. That requires an after-cat O2 sensor. A 1995 F-Body LT1 has an OBD-1 PCM, and no after-cat O2 sensor. The 95 does have a 16-pin OBD-2 style DLC, but requires an OBD-1 scanner, and an adapter, or jumper wires:

from Shoebox:

http://shbox.com/1/xraycable.jpg

 

oh dam so the code i got was incorrect? i scanned it with the autozone scanner. where would i get an adapter and those wires ?
and thanks for your response!

edit: i will get my hands on the voltage meter tool it comes when u rent the fuel
pressure gauge from autozone . is there anything i test that can be a possible cause ?

 

Are you sure the car is a 1995, and not a 1996, which is OBD-2?

The OBD-1 scanner manufacturer may offer an adapter for their cable, or they may offer a cable specifically for the GM cars that used the 16-pin connector with an OBD-1 PCM. If you have access to an OBD-1 scanner, but do not have an adapter or the correct cable, you make the two jumper wires yourself.

There are also scanners available that can scan both OBD-1 and OBD-2, but a couple of the most popular ones have a faulty database for the LT1 engine, and will show seven incorrect codes. Equus is one of them, Innova is the other. Actron is reliable.

Start with the basics - fuel and spark. While the engine is cranking, hold the plug end of the wire near the plug or a ground, to see if it sparks. Don't hold the wire with your hand or anything metallic, or you may experience a 20,000 volt jolt. You can also get a “spark tester” that inserts between the wire and the plug, and makes the spark visible inside a transparent tube.

if it becomes necessary to go beyond fuel and spark, download free Scan9495 software, purchase the correct cable to connect a laptop, and you can view 50 different sensor readings and PCM parameters, along with codes.

https://www.camaroz28.com/forums/com...95-lt1-874306/

 

yeah im sure its a 1995 it says so on the pink slip and carfax verified. and thanks for the link i will go ahead and look for those wires n adaptor... i will begin with the basics like u mentioned and go deeper from there

 

ok heres the results , i took my battery to oreilys and was told it was good just needs a charging, 45 mins later i was told the battery is bad after charging ...

i tested the new pump and on first prime it jumped to 40 psi and after second prime it jumped to 42 then back to 40, and it actually turned on today 🤔 :
a few seconds into it starting the check engine light came on , and here is the dash gauges, battery voltage reads halfway and oil guage jumps a lil and ses light is on :
a few seconds while it idled it then proceeds to shut off :
this is the second attempt of firing it up , only turned on after giving some gas , and then again it shuts off after a few seconds of idling , as u can see the psi readings go up n down :
i just realized there is a pattern , after disconnecting the battery for at least 2-3 hrs the computer forgets about the SES light and it fires up on first try , and then shuts off after 2-5 mins of idle , it wont fire up again after the SES light has turned again. after the light has been on it wont start again , i have to disconnect the battery again for a few hours and its the same process again.....im almost sure that SES light is telling me what part is bad and needs immediate replacement for it to start again....and i wont be able to get codes till i figure out how to check the codes for the darn obd1 computer with the obd2 connector. i will have to find the adapter and wires to get the code...but from this does anyone know what can be the issue ??

 

here is the readings with the old pump , and like i mentioned earlier this was prior to having the battery disconnected for a day resulting in the computer forgetting it had a SES light on :
here is the second attempt where it actually fired up with the old pump during the same test , it shut off again shortly:

 

Old pump was defective. New pump is fine. I assume the fuel pressure at idle for the new pump was done with the vacuum compensation line attached to the fuel pressure regulator. ~35 PSI is OK for that condition. If you had removed the vacuum line while it was idling, the pressure would have risen to about 43 PSI, which is right where it belongs.

Battery gauge (volts) is right where it's supposed to be. At startup, the voltage regulator bumps the voltage up a bit to replace the battery power that was used to start the engine. As the power in the battery is replaced, the voltage will drop gradually. Within the range of 13-13.5 volts is fine.

It's completely normal for the oil pressure to move with RPM variations. Pressure actually looks good for a cold start.

When you remove battery power to the PCM, it clears the stored trouble codes. Also clears the stored long term fuel trims (LTFT), which is good because the low pressure of the old pump was causing A/F ratio problems, and the PCM adjusts the LTFT's to correct the problem.

You need to scan to find out what code is turning in the SES light. There's nothing obvious in the videos to indicate what is causing it to stall.