If I drive my car for a while, especially if the weather is hot, it sporadically gets fuel pressure issues. It starts to hesitate and stumble. If I let it sit for an hour or so, then it runs fine again. The dash shows no check engine light on. I found that the pressure is fluctuating when the issue happens and when it fails and I turn the key, there would be no pressure at all. I had CPS, CAS and EGI main relay replaced, along with the fuel pump. The other day when it was a bit warmer, I drove it and it ran great, but after about half an hour of sitting, it couldn't be started. What could be the issue here? Thank you.
An erratic fuel pump may be one of a few different problems. You need to check to see if the fuel pump is getting power when the problem is happening. If it is, then the ground in the right rear wheel well needs to be checked. If both are okay, then you have a bad pump.
You said you replaced the pump before, but the pump may be bad again. When you have the pump changed, the fuel tank should be checked for small metal particles in the bottom. These particles will overheat a pump and stop it, and the car will not start again until it cools down and passes the particles until it gets warm again. Make sure the tank is cleaned out very well and I also recommend changing the filter again.
If you need to have this done, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose your car’s hesitation issue and perform any repairs that are necessary.