LT1 Stalls When Hot? Smell Fuel? Pump Making Noise? Look here
10-11-2012, 09:26 PM
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LT1 Stalls When Hot? Smell Fuel? Pump Making Noise? Look here Hello fellow LS1 Tech members. I'm making a post to try to help anyone who is experiencing problems with vapor lock, fuel pump noises, and excessive pressure in the fuel tank.
I have had an issue with my 97 Trans Am since I got it where when it gets warm outside, the fuel pump would start running very loud and the car would start running horrible and stall out. This was because my EVAP system was not working correctly and was allowing to much fuel vapor to build up in the tank. I had a SES light on, indicating that the evap system was not getting flow. I took a look at the Purge Solenoid which is located by the passenger side valve cover, un hooked the hoses and discovered pieces of charcoal in the system. When you have bits of charcoal anywhere in the system it means that the charcoal canister which is located behind the driver side rear wheel splash shield has broken apart. You must replace the canister to fix this issue.
So now I replaced the canister. No SES light, but I'm still having the same problem as before. Lots of pressure and a smell of raw fuel from the area of the canister. I then moved to the next possible thing that can be causing the problem, The Pressure Control Valve. This valve is what allows fuel vapor to leave the fuel tank and go into the charcoal canister. If this valve is not working right, it will not allow the tank to vent to the canister causing too much vapor to stay in the tank and vapor lock the engine. I replaced the valve, along with the hoses which were old and falling apart and have not had the issue come back.
Now lets move on to Fuel pump noise. These cars have a weird design when it comes to the fuel tank. If you are low on gas with these cars, you will hear the pump running. Its completely normal. If you are hearing really loud noise and experiencing driveablitly issues, then the problem is to much fuel vapor in the tank which means the EVAP system is not working correctly. You are more prone to noticing an issue like this when it is hot outside. More fuel vapors are present as the outside temp gets hotter. Some people also report that when they take the cap off, alot of pressure comes out. Even with my evap system working fine, I still get a good amount of pressure that comes out. Not as strong where its going to throw the cap out of my hand though.
If anyone has any suggestions or additions to add to this please reply and add your info. I wanted to write about this to try and help others because it seems to be a pretty common problem.
1. A bad pressure control valve on these cars will NOT set a check engine light.
2. This system is not suppose to have a vented gas cap.
3. Can you bypass the charcoal canister? Of course. Simply remove the canister and plug the vacuum line with a bolt. This will not set a SES light however the rear of your car will smell like raw fuel all the time.
4. These cars do suffer from Fuel Starvation. If you are low on gas and make a sharp turn or brake very hard, the engine could stall due to the shape of the tank.
5. The evap system in these cars consists of the Purge Solenoid, Vacuum Switch, and the pressure control valve.
I have had an issue with my 97 Trans Am since I got it where when it gets warm outside, the fuel pump would start running very loud and the car would start running horrible and stall out. This was because my EVAP system was not working correctly and was allowing to much fuel vapor to build up in the tank. I had a SES light on, indicating that the evap system was not getting flow. I took a look at the Purge Solenoid which is located by the passenger side valve cover, un hooked the hoses and discovered pieces of charcoal in the system. When you have bits of charcoal anywhere in the system it means that the charcoal canister which is located behind the driver side rear wheel splash shield has broken apart. You must replace the canister to fix this issue.
So now I replaced the canister. No SES light, but I'm still having the same problem as before. Lots of pressure and a smell of raw fuel from the area of the canister. I then moved to the next possible thing that can be causing the problem, The Pressure Control Valve. This valve is what allows fuel vapor to leave the fuel tank and go into the charcoal canister. If this valve is not working right, it will not allow the tank to vent to the canister causing too much vapor to stay in the tank and vapor lock the engine. I replaced the valve, along with the hoses which were old and falling apart and have not had the issue come back.
Now lets move on to Fuel pump noise. These cars have a weird design when it comes to the fuel tank. If you are low on gas with these cars, you will hear the pump running. Its completely normal. If you are hearing really loud noise and experiencing driveablitly issues, then the problem is to much fuel vapor in the tank which means the EVAP system is not working correctly. You are more prone to noticing an issue like this when it is hot outside. More fuel vapors are present as the outside temp gets hotter. Some people also report that when they take the cap off, alot of pressure comes out. Even with my evap system working fine, I still get a good amount of pressure that comes out. Not as strong where its going to throw the cap out of my hand though.
If anyone has any suggestions or additions to add to this please reply and add your info. I wanted to write about this to try and help others because it seems to be a pretty common problem.
1. A bad pressure control valve on these cars will NOT set a check engine light.
2. This system is not suppose to have a vented gas cap.
3. Can you bypass the charcoal canister? Of course. Simply remove the canister and plug the vacuum line with a bolt. This will not set a SES light however the rear of your car will smell like raw fuel all the time.
4. These cars do suffer from Fuel Starvation. If you are low on gas and make a sharp turn or brake very hard, the engine could stall due to the shape of the tank.
5. The evap system in these cars consists of the Purge Solenoid, Vacuum Switch, and the pressure control valve.
Last edited by Phil424; 10-11-2012 at 09:35 PM.
