ok as the title says my truck wont start. i have a 92 chevy 1500 ext. cab 5.7 v8 with about 210,000 miles it has a few problems but this one concerns me the most. the odd thing is my truck starts when its cooled down or cold weather but it wont start when it has been running for a while, like if i drove it more then 40 minutes. and when it wont start i don't hear nothing other than the fuel pump priming so i have to jump start and it will run fine. i did get engine light and it was code 54 fuel pump relay low voltage or something like that. i remembered i switched out the relay one time and today i changed it back to its original one luckily i still had it and started it up and i didn't see the code anymore. so is there anything i need to check? thanks in advance