No start

1999 SW2 was running fine-got full tank of gas on Sunday night, and didn't use the car until Tuesday night. Went to start the car, and the engine just cranked. I noticed that the fuel tank gauge was not moving. Later in the evening, I checked the 10 amp fuse (lowest amp should blow first) and it was ok. I tried starting the car again, and it started to catch. I pulled out the fuel pump relay but you can't tell anything by just looking at it and reinserted it. When I tried starting the car again, it cranked right up. The fuel gauge took a couple of seconds but it also worked. I noticed that when I shut the engine down and turned the ignition back on right away, the fuel gauge responded instantly. But if I left the ignition off for a minute or so, when I turned the key to Acc, it took the fuel gauge about 3 or 4 seconds to respond. I don't know if any of this is pertinent, but with electronics all tied together I wanted to tell all.

Now the car is starting fine, but the 'check engine light' is on. I am bringing it over to get the code read, but would like to get any imput as to what could be wrong.

I am not comfortable letting my wife and kids use the car until I know what happened.

Thanks for the help