2000 Gp GTP starts but dies 2 secons later

[99GPGTP]

my co worker has a 2000 grand prix gtp 2door that will spin over and fire up but dies 2 seconds later, no codes stored. sometimes when i hook up scanner i get no comunication, all fuses are good in car. the DIC doesnt work at times but im pretty sure thats not the cause. i think its a symptom. sometimes the car will fire up and run just fine. couple months ago it had a security code but not any more. the security light goes after a couple seconds of putting in the key and turning ignition on.
if anyone has any info that might help is please let me know. i work as a mechanic but this has us all stumped. we do know the fuel pump still runs and has fuel pressure. the injector noid goes away and car dies.

[99GPGTP]

also. it still fires when it dies, new cam and crank sensor

[Scottydoggs]

try this.

[99GPGTP]

car has great fuel pressure. do u think that will fix this?

[willie14]

Is this bypass a way to just get more out of stock fuel pump & injectors? Curious it seems to be a similar resolve like the voltage rewire kit...

[Scottydoggs]

no. its to bypass the high speed resistor when it fails. read the words on the pic.

[Scottydoggs]

car has great fuel pressure. do u think that will fix this?

its worth a shot. start and stall is related to that pic and the resistor, bending that tab puts the pump in hi speed mode full time.

[99GPGTP]

tried bending the tab, it didnt help. car still dies after 2-3 seconds
forgot to mention. fuel gauge stopped working and this problem started. Installed new fuel pump last month. problem still there. used a delphi stocl replacement pump. new fuel pump relay also

[Scottydoggs]

the security light on? maybe try another key?

[Fivefingerdeathpunch]

Security relearn is the next step to me or try another key.

[99GPGTP]

tried another key, security light goes off. i think its the pass lock

could the icm cause this.

[99GPGTP]

just found the problem, had a loose ground on the battery cable to the body

[Scottydoggs]

nice find.