1990 5.7. Was hot in CA last week (110F) and I sat idling with A/C blasting for 30 minutes which I don’t often do. Short trip home and I had to go out again 20 min later. Crank no start. Sprayed some carb cleaner down the intake and she fired. Had to be a fuel issue.
The pump would prime upon KO but it sounded more muted than normal. That’s about all the diagnosing I did as I Had to skeedattle and grabbed another vehicle for my errand. When I came back she fired no problem. Been running normally since.
Did some research on if vapor lock is even possible on a TBI and saw mixed opinions. Digging into the troubleshooting manual, there is actually a hot fuel module that is specifically intended to prevent vapor lock on TBi 454 and R body 5.7s by energizing the fuel pump for 20s on KO instead of the standard 2s. This leads me to believe that vapor lock is possible for a TBI.
Now, I live in the desert, so driving in heat is the norm. It took a long time of what I would consider extreme environmental operation to cause this symptom so I’m not too worried about it. Will keep it in the back of my mind for future reference. Perhaps I’ll make up a jumper so I can manually engage the fuel pump from the ALDL if I don’t have time to wait for a cool down.
The pump would prime upon KO but it sounded more muted than normal. That’s about all the diagnosing I did as I Had to skeedattle and grabbed another vehicle for my errand. When I came back she fired no problem. Been running normally since.
Did some research on if vapor lock is even possible on a TBI and saw mixed opinions. Digging into the troubleshooting manual, there is actually a hot fuel module that is specifically intended to prevent vapor lock on TBi 454 and R body 5.7s by energizing the fuel pump for 20s on KO instead of the standard 2s. This leads me to believe that vapor lock is possible for a TBI.
Now, I live in the desert, so driving in heat is the norm. It took a long time of what I would consider extreme environmental operation to cause this symptom so I’m not too worried about it. Will keep it in the back of my mind for future reference. Perhaps I’ll make up a jumper so I can manually engage the fuel pump from the ALDL if I don’t have time to wait for a cool down.