Hello everyone.I've got one of those mysterious fuel related problems on my 1989 Formula 350.I thought this was a fuel starvation problem at first,probably meaning the fuel pump or fuel filter.After a few weeks I've noticed that: A) leaving it in the hot sun brings on this stumble/leaving it in the hot sun with the hood raised does not. B) Slow stop-and-go driving conditions bring on the problem. C) Parking it overnight or raising the hood for a good long while(when problem is occuring) seems to clear things up. After searching through the forums I've come up with; fuel pump,fuel filter,oxygen sensor,iac valve,egr valve,maf,fuel injectors,vapor purge cannister and fuel pump relay.I also wonder about the fuel burn-off relay.The car isn't throwing any codes,so this week I will start with the simpler issues before moving to the dreaded fuel pump.Just was hoping someone here recognized the strange hood raised/hood shut variable(which could be coincidence or in my head,but after 3 weeks probably not).Thanks for reading.

 

I HATE pulling the gas tank! Pain in the aZZ . i had a problem like that ? but having the hood open never fixed it . a new fuel pump was what i needed >

 

let me know what the problem is when you find it. i have the exact same problem with my sunfire.... (my dd since i am working on all three of my camaros)

 

Opening the hood seems like it would release trapped heat.I wonder if the heat could affect the electronics such as relays,or have something to do with leaking injectors or other sealed components.I am going to do some more searching on the vapor cannister this evening as well.

 

After reading more about the vapor cannister and the other vent line coming from the tank,I'm also wondering if one or both of them being blocked could somehow cause this stumble.Possible?