Car question

[glatt]

I have another car question. Yay!

This one is about a 2001 Toyota Camry.

We bought this car used about a year ago, and so don't know its history or what "normal" is for it. No idea if all proper maintenance had been performed because maintenance records are incomplete, but the car has fairly low miles (65k) still and it appears to be in pretty good shape.

Sometimes when driving on a highway at steady speed, I would notice a very very slight fluctuation in engine power. Kind of like a stuttering. But so minor, that I thought it might perhaps be my imagination. Except I was sure it was actually there. This has been going on for the past 3-4 months very intermittently. We buy brand name gas. This stuttering was not a big deal, because is was barely noticeable, and others in the car didn't even notice it.

Last weekend, after driving on highways for about 2 hours on our way to the beach, we got to a surface street and had to stop for a light. When it was time to go again, the car wouldn't move. And the check engine light was on! After a moment of panic, I realized the car had stalled, but I hadn't heard the engine stop because the radio was so loud. The check engine and a couple other lights were on, but went off when I restarted the car. It started fine. We continued on our way.

We had about 15 more miles to travel to our hotel, and the car was sputtering intermittently the entire way. It stalled two more times, in spite of my efforts shifting into neutral and giving it some gas as we stopped at lights. The last time it stalled, it started back up again and behaved perfectly normally for the last mile or so to the hotel.

Driving it the next few days at the beach, it behaved perfectly normally.

On the 3 hour drive back home, it behaved perfectly normally.

I tinkered with it in the driveway at home and it behaved perfectly normally the entire time.

the clues:
-There is no check engine light on, and no diagnostic codes. I assume this means the spark plugs are firing, because I think the computer would report no spark.

-It behaved a lot like a lawn mower running out of gas. Except the tank was 3/4 full when it stalled.

-The repair manual says that when you turn the ignition key to the "on" position, you should hear the fuel pump whirring for about two seconds, and then it will turn off. When I turn the key to the "on" position, the fuel pump does not run. The fuel pump doesn't begin running until I turn it to "start."

-I checked the fuses and relays that the manual said I should check, and they appear to be fine. One relay check was only a partial check though, but I swapped it with an identical relay for the horn and the horn still worked and the pump still didn't.

-I pulled out the back seat and checked the voltage at the connector to the gas pump when the key was turned to "on." It had battery voltage at one conductor and 5 volts at another. The manual didn't say what it should have.

-I saw a creepy little spider crawling around on top of the gas tank when I opened the hatch under the back seat to look at the fuel pump connector. How long had that guy been there?


So do I just go ahead and replace the fuel pump? They cost like $200 for the part, and there's also some whirlygig contraption next to them that controls them and I don't know what they cost, but they look expensive and complicated.

I also noticed that there is no little metal flap on the gas tank opening on this car. Every other car I've had has one of those little flaps under the gas cap. Could that flap have fallen into the tank and blocked something? Or didn't this car have one?