I've thrown this out here before but no one has had this happen to them, or at least back then so I'm going to throw this out here again. My problem is this: when it gets Hot out, as in 90-100 degree summer days, the engine will sometimes sputter like it has no power and won't get very high rpms if I floor it. Then it will eventually shut off. Its like it can't breathe or its not getting enough gas feeling. This will also happen if I'm driving down the highway and all of sudden I can't accelerate and start dropping in speed until the car slowly comes to a stop. In both cases, I stop the engine and I can wait 5-10 minutes, start up the engine and it will be fine. When I shut it down or it shuts itself down and if I try to start it up in under a minute it will never start or it will have hardly enough power to move the car. Sometimes it will sputter for a little while and come out of it. The engine temp doesn't have to be that hot for this to happen. I run 89 or 90 octane gas always. It doesn't matter if I take the air filter off. I have replaced the fuel filter probably twice now and just replaced it last summer. Fuel pressure is good but I've never been able to check it when this weird stuff happens. This seems to only happen every other summer but last summer it happened probably 5 times. If I pull over and take off the gas cap it will hiss out air for like 30 seconds(or a really long time). 1992 3.1 V6. You guys have any suggestions before I start throwing parts out it to avoid headaches this summer? I'm leaning towards injectors getting too hot and I doubt they have been replaced ever.

sounds more like the engine is overheating...

No it never overheats, I could let the car not run all day and then start it. In under 30 seconds this could happen and has happened before in under a minute after starting the car.

I had a similar issue with the ignition module. Perhaps clean the thermal grease off of it and reapply liberally?

Think I figured out what caused this in my v6. Whenever I take off the gas cap now in higher temperatures there is a huge whoosh sound that lasts a while. There is a gas tank vent valve that connects to the fuel pump sending unit, that thing that hangs by the tank and above the rear. I think it failed causing pressures to build up so high that the high-mileage fuel pump couldn't function. The fuel pump failed last winter and I need to replace this vent valve thing. I had a similar episode happen to my LT1 car that had no vent causing a bad walbro fuel pump in under 200 miles.

pressure relief valve in your gas cap may be stuck that was the cause in my daughters vw jetta .

Dead post, there, dude.

Either way, that pressure relief only goes one way (out, not in). The tank vapor pressure relief valve the OP is referring to maintains the tank pressure, letting air in under vacuum, and releasing fuel vapor under pressure. If the tank stays under vacuum, the fuel may not be able to be taken up by the sending unit so the engine starves for gas.

I was going to say vapor lock, I learned that a long time ago!
Was with a friend in his vet, driving up a winding road to a high mountain and his started doing the same thing. I said pull over and unscrew the gas cap, but don't take it off > gas sometimes spews out if you do. He did and the pressure was crazy.
Once he did that it was fine. I would just like to know whats the fix for the built up gas pressure?

It's not fuel pressure, it's the vacuum that develops in the tank that causes the issues. Only way I can think to fix it is to replace the pressure relief valve located on a bracket behind the driver's rear wheel, and I'm not sure they can be bought at the dealer or not. May need to make some sort of bracket and shield and put a breather filter on there or something.

I have a 1991 RS 5.0 TBI all stock except flowmaster, and I live in Phoenix, the car never liked hot weather to begin with but Friday I was in stop and go and it was 114* out so she was gettin real hot but not in any red danger zone and then she started to sputter so I chucked it in neutral to try and keep it running and it sputtered for 10 sec. then died, It fired back up and let me drive a little more then did it again, so I made it to a parking lot, let her cool then I got on the freeway and she took me 30 miles all the way home without dying, it's gotten hot before but never did this, this is a first, I just put new plugs in her and a new cat and a new EGR a few weeks ago because of a failed emmission, turns out it was the EGR, but she was due for plugs anyway and all was fine until she got hot now she is running with a high idle now and seems to drag a little bit like a low battery on a cold start. Any intelligent suggestions anyone?

87 Trans Am, 5.7l and auto tranny: Ive been fighting this same problem. I've replaced the Fuel pump, Filter, rubber lines and the fuel tank vent valve and STILL have this problem. In the heat of the late afternoon and evening, it will stutter, sputter, stall and die. You can floor it and sometimes it will take off only to do it again but sometimes it just dies. Help?

The same **** for me too, and then it will run fine the next day unless I run it in late afternnon traffic when its like a boiling pot of pasta outside, you can literly cook an egg on the asphalt!!!! Only does this when its over 102-112* outside, under that see has not bucked at all