Ticking Every 2 Seconds From The Fuel Tank?

[deepcdiver]

My 1990 LS400 with 196k miles has a loud ticking (or soft tapping) I just noticed yesterday, coming from the right rear of the car. Could it be the fuel pump? Are there two pumps? It is a steady tap. every two seconds....

The car has been running rough for quite awhile now, (but will sometimes run for days just fine) but the ticking noise is definitely new. I just tonight started searching for the answer to the rough running, including the trunk hinge wiring harnes, MAF, and...I see the fuel pump could be the culprit (along with coils, plug wires and the other usual electrical culprits).

I did a search on the tapping and did not come up with anything.

Thanks!

[nc211]

a little more info needed. do you hear the tick with the car just sitting at idle? If so, get out and put your ear to the gas cap. Make sure it isn't a loose cap that is hissing/ticking off the pressure. Also, how much fuel do you have in the tank? how much do you usually have in there? run it close to empty a lot? I ask because the fuel acts as a coolant to the pump that's inside the tank. If you run the tank on E a lot, you're actually letting the fuel pump heat up. Also, it works harder too when on E to capsure the fuel sloshing around in there.