What is the normal duty cycle for the fuel pump ?

[oragex]

Can someone read on Vida the normal duty pump cycle ? I read online either 40% or 50% ?

[Rvolvos]

Can someone read on Vida the normal duty pump cycle ? I read online either 40% or 50% ?

Hi Oragex,
While idling our 2006 xc70 194k duty cycle of the fuel pump is around 40%

[oragex]

Thanks. So it seems a 50% duty is too high. I guess I damaged the pump by keeping the tank low for too long. The pump sits inside a cup filled with gasoline at all times, but it seems this cup does not provide enough cooling for the pump if the tank is always low. Lesson learned. My pump relay would heat up too much in summer time and the pump would shut down while driving.

[gnalan]

My pump relay would heat up too much in summer time and the pump would shut down while driving.

How did you keep from wrecking?

I hope you fixed it so you'll be safe. I've heard about some bad wrecks from fuel pumps shutting off and causing wrecks. My dad was driving years back when his fuel pump died. He lost all control when the power steering and power brakes didn't work anymore, and he slammed into a telephone pole less than a mile from home. He walked home, and was ok, but the car didn't survive the wreck.

[csh]

My rule of thumb is to not go below a quarter tank under most circumstances. One of the reasons is to keep enough fuel in the tank to help keep the fuel pump cool and the other reason is to ensure that any time I get in the car I have at least a quarter tank of range.

We had a car in the past where there was a known issue with fuel pump cavitation. When the cavitation would occur it was usually a combination of two of three factors that would lead to cavitation. Winter fuel (higher volatility formulation), summer heat, and/or elevation would combine to create the conditions where cavitation would occur. Waiting a few minutes to let the fuel pump cool would allow the car to be driven again until the next engine stall caused by cavitation. This could be the reason for the stall. I'd be surprised if the fuel pump relay had thermal protection in it.

gnalan, One of the things meant to do for my kids when I was teaching my kids how to drive is what happens when the engine stalls. You can still steer the car, but it takes more effort. And you have one or two presses of the brake pedal before you run out of vacuum in the brake booster. In my younger days when I did a lot of dumb stuff I ran out of gas while driving down hill. I knew there was a gas station at the bottom of the hill and managed to get the car to coast .5 -1 mi down the hill and into the station near a pump where I could refuel. Dumb and lucky I guess.

[abscate]

For us, 1/8 tank in summer, 1/4 in winter.

[vtl]

VIDA says 35% +/- a bit for a new pump. By 65% they almost certainly die. My pump is at ~50%, the car has 265k on the odo.

[gnalan]

VIDA says 35% +/- a bit for a new pump. By 65% they almost certainly die. My pump is at ~50%, the car has 265k on the odo.

I replaced my fuel pump right after I bought my car this summer. I'll check what my duty cycle is tomorrow, if I get a chance, and post what it shows.

[abscate]

VIDA says 35% +/- a bit for a new pump. By 65% they almost certainly die. My pump is at ~50%, the car has 265k on the odo.

That’s great info if VIDA can be used to determine the state of the fuel pump age.

[vtl]

VIDA says 35% +/- a bit for a new pump. By 65% they almost certainly die. My pump is at ~50%, the car has 265k on the odo.

That’s great info if VIDA can be used to determine the state of the fuel pump age.

Only for those model years having the PEM (fuel pump module). Older or European cars don't have it.