I think what the scan tool is illustrating is fuel tank vent valves; one or both are malfunctioning. If you have G.M. model car this is a common problem and most models they are easily accessed.
some type of gas tank vent stuff
remedy for those nagging check engine soon lights but nothing wrong. Put a piece of black tape over it so it's not so bright
. Some states and city metropolitan areas require this to be repaired during a vehicle inspection before you can get your license plates
My story is a little embarrassing because of being a car/light truck technician for 40 years. (Mostly Chevrolet and a little Ford).
A few years back a retired couple bought a new Silverado at a Chevrolet dealer I was working at and management asked me to do a pre delivery inspection in front of the customer. This was not very common pulling a line technician off the job to satisfy a customer, so I asked why. The explanation was the customers previous truck started having issues that couldn’t be repair and they wanted to be sure their new truck was ok before they took it and do whatever it takes to satisfy the customer to get the truck out the door. My thinking was at the price they paid for their new truck it was justifiable.
When I was performing the inspection the new owner and I had a long conversation about his new truck and also the issues of his old truck. His old truck was a “top of the line Dodge” that developed an intermittent engine miss at 80,000 miles only when the transmission shifted into second gear under light acceleration for about four to five seconds. He also told me he only took it to Chrysler dealers for service and he personally spent a lot of money with no remedy of the engine miss. Chrysler engineers got involved because the engine miss-fire was emission related and they thought maybe there was a PCM (Computer) programming problem but, they couldn’t find the problem either.
The retired couple traveled a lot and pulled a RV and they thought it was time to get something different. The customer was very honest and told the dealer about the issue of their vehicle because mostly they didn’t want a new owner to go through what they did. Little did they know the dealer could care less and the truck was headed to the wholesale area or to an auto auction.
At the time I was looking for a truck for my then high school son that had small business that required a pick-up truck that could pull a trailer. After work that day I checked the Dodge out and it was a nice looking truck so I got permission to test drive it. When I drove it, I didn’t feel an engine miss-fire and decided to negotiate with the dealer to buy the truck. About a week later we came to a deal.
After a period of time the truck started to do exactly what the PO said it was doing to them. The funny part was; when you accelerated hard and when pulling a trailer up a hill the engine would not miss-fire only under light acceleration from first to second gear change. After about one year of my diagnosis plus technicians that I knew that could fix anything we gave up. From time to time I would try different things but no fix was obtained.
After a while the truck was passed down through all my sons. My youngest son who had the truck force on him cut and sold wood in the winter and ran a truck farm in the summer to help pay for college. The truck pulled a trailer most of the time and he was after me to do something with the engine miss. I than tried everything again with the same outcome.
After a period of time my son told me he did a Google search with the problem we had with our Dodge and he said a person posted they had the same problem with their Dodge and after two years of their truck in and out shops they decided to drive it until the problem became more prominent. They stated in the Google post about a year after trying to fix their truck one day it started missing more and stopped running completely. They had it towed to a repair shop and found a fuel pump failure. After the fuel pump was replaced the trucks engine miss-fire was gone. The repair shop took the fuel pump apart and found a badly worn armature at the brush contract.
I couldn’t believe what I was reading. One of the tests I did during my diagnosis was a fuel pressure check. In fact I taped the head of the fuel pump test gauge to the windshied of the truck while I was driving to confirm the fuel pressure specs while the engine miss-fired. The fuel pressure was two pounds above specs!!!
After some arm twisting from my son we found a fuel pump on E-bay for a reasonable price. The fuel pump was replaced and the engine miss-fire was gone. We took the pump apart and found a badly worn armature at the brush contract.
During a conversation with an aviation hydraulic technician at a college my son attends and telling her about our dilemma she said "on fluid pumps not only pressure is important but flow is more important”.
Obviously the fuel pump was the problem for the engine miss-fire. I didn’t have the equipment to check the fuel flow for the fuel system and I guess the previous techs during their diagnosis didn’t either. It still bewilders me how the engine can run good under pressure and run bad under light pressure with a fuel flow problem.
We still own the truck and after 226,000 miles it still running good.
Links of the truck earning its way…http://img.photobucket.com/albums/v688/Jackf/Making%20a%20Living%20the%20Old%20hard%20Way/Wood.jpghttp://img.photobucket.com/albums/v688/Jackf/Making%20a%20Living%20the%20Old%20hard%20Way/Deer.jpg