Ruining An In Tank Electric Fuel Pump?

My truck has a fuel temp. sensor.

ScottG wrote:

Dutch_12078 wrote:
Are you all overlooking the role the fuel return line plays in cooling the pump?

I don't know about a gas engine but in a diesel, it actually causes the fuel in the tank to be warmer, not cooler.

Warmer than the fuel pump?

Dutch_12078 wrote:
Are you all overlooking the role the fuel return line plays in cooling the pump?

I don't know about a gas engine but in a diesel, it actually causes the fuel in the tank to be warmer, not cooler.

Well something is getting missed here. When a tank pump no longer has fuel two things happen. A-the amps drop (the fuel provides resistance) and the pump can double the rpm's that it normally runs. Do you think MEX that it could cause heating issues?
Have a good one MEX

Are you all overlooking the role the fuel return line plays in cooling the pump?

My daughter sent me a pic last summer of her dashboard when it said 105 degrees. I texted her back and said I thought I told you not to run so low on fuel. She responded that it struck her as soon as she had sent the pic that I was going to see her fuel gauge and say that. That's ok, I'm no longer on the hook, now it's her fiance. :)

I've worked on several different kinds of pumps, albeit larger than fuel pumps, and most of them would overheat/fail if not supplied with the material they were designed to pump. The pumped material probably acted more as a lubricant than coolant. With nothing to pump there is no "lubricant" so if the pump is slightly worn, there is nothing to keep metal/plastic/rubber/graphite parts from rubbing together in ways they were not designed to do.

A brand new out-of-the-box pump should not have parts touching normally so it shouldn't be a problem.

MEXICOWANDERER wrote:
Pickup is several inches BELOW the lowest point of the motor.

Internally/externally mounted fuel pumps for fuel injected gasoline engines are typically referred to as roller cell pumps. (very different from older electric pumps for carburetted engines) They are cooled by running the fuel through the pump assembly including the pump motor. (Bosch style pumps) Yes, the DC brushed motor is internally bathed in gasoline during operation. If the pump is mounted inside the fuel tank it receives additional cooling because it is immersed in fuel when sufficient fuel is in the tank to cover it. These pumps can be noisy so submersing it in fuel does tend to dampen the whine but it can cause servicing to be difficult if there is no access plate provided in the upper portion of the tank. When/if the vehicle runs out of fuel, cooling is generally not a problem because the engine quickly stops. Usually fuel injected engines have a fuel pump relay that automatically stops the pump if it doesn't see an ignition signal. (engine isn't running) They also have an inertial switch that stops the pump in the event of an accident.

Newer style fuel pumps use a turbine wheel in place of a roller cell but generally work the same way.

Chum lee

The pump usually sits in a well of sorts. So even when the tank is on "empty", the tank is still submerged. However, on a long drive that remaining fuel will get warmer than if the tank had more fuel in it.

Have been told by a trusted professional to never run one dry for more than a few seconds. Dry as in on the workbench. That has more to do with ruining the pump section than overheating the motor. Just talked to him and he said he has never heard of a pump overheating because the motor was not submerged.