QuestionQUESTION: Recently the vehicle will turn over but not start. Pump comes on, when we spray the starting fluid under the hood (not sure what it was that it was sprayed into) but anyway, it eventually started up. Runs real smooth when started, when I shut it off it will restart fine. After sitting for a while though it will either have a rough start or not start at all. Im down to a fuel tank pressure sensor. Any other thoughts? Thanks
ANSWER: It is most likely the fuel injection unit inside the manifold. They are notoriously unreliable. A failure can cause lean or rich running, depending on the failure mode. The coolant temp sensor can also cause a starting problem. If the sensor fails, the computer may assume that the engine is warm when it is cold. Then, it gives too lean a mixture to get it started cold (cold engines require a richer mixture, which is what the choke was for in the old days). A coolant temp sensor is very cheap and worth trying before you dig into the fuel injection.
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QUESTION: We haven't heard to check that but I did want to mention mainly I forgot to in the first question. We put a code reader on and found one code which was P0452. It did not find anything else, the check engine light is not on either. Thanks
ANSWER: That's an evap emissions code. if there's a leak in the evap system, it would act just like a vacuum leak and create a too lean running condition, making it hard to start. Leaks in these systems are a little hard to find, an experienced Chevy guy should be able to run it down, though
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QUESTION: Hello, We had a problem with this and the vehicle wouldn't start for a week. We changed the MAP sensor and the vehicle started right away, then we did change the Vapor Pressure Sensor on the tank. Now it doesn't want to start again. could i have received a defective map sensor or do you think maybe something else is causing this? Thanks for any opinion.
Answer I'm still inclined to think that you have a problem with the fuel injectors 'cause everyone does. I'd do a very thorough search for vacuum leaks first, and then pull the manifold apart to look at the injectors. The part that fails is a hard plastic, and it gets brittle over time, then leaks fuel. So, it won't maintain pressure between starts and it doesn't deliver properly atomized fuel when running.
