Fuel pump cooling
05-24-2024, 11:03 AM
#2
05-24-2024, 11:23 AM
#3
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PFL205.064 with M276.823 (Oil pump solenoid defeated)
05-24-2024, 12:14 PM
#4
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The pump is always being cooled by the fuel; the problem is that at very low fuel levels (below 1/4th of a tank) the decreasing volume of fuel available to dissipate the heat produced by the return fuel is less and less, meaning the fuel temp in the tank increases.
After a certain temp pre-determined by the ECU and detected by the fuel temp sensor, the ECU begins to retard timing which results in decreased power. At the same time, the fuel pump itself is getting hotter. I think you'd run out of fuel before anything catastrophic happens to the pump, but I think over time damage is caused by all of the hot/cold cycling. Hopefully it's the LPFP that croaks first since that's cheaper and easier to replace than the HPFP.
My advice is don't needlessly drive around with 1/4th of a tank of fuel or less; make it a habit to fill up before then. This is even more important for diesels and in winter, as it helps prevent running out of fuel at the worst time and aids in preventing fuel gelling.
After a certain temp pre-determined by the ECU and detected by the fuel temp sensor, the ECU begins to retard timing which results in decreased power. At the same time, the fuel pump itself is getting hotter. I think you'd run out of fuel before anything catastrophic happens to the pump, but I think over time damage is caused by all of the hot/cold cycling. Hopefully it's the LPFP that croaks first since that's cheaper and easier to replace than the HPFP.
My advice is don't needlessly drive around with 1/4th of a tank of fuel or less; make it a habit to fill up before then. This is even more important for diesels and in winter, as it helps prevent running out of fuel at the worst time and aids in preventing fuel gelling.
05-24-2024, 03:59 PM
#7
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PFL205.064 with M276.823 (Oil pump solenoid defeated)
The pump is always being cooled by the fuel; the problem is that at very low fuel levels (below 1/4th of a tank) the decreasing volume of fuel available to dissipate the heat produced by the return fuel is less and less, meaning the fuel temp in the tank increases.
After a certain temp pre-determined by the ECU and detected by the fuel temp sensor, the ECU begins to retard timing which results in decreased power. At the same time, the fuel pump itself is getting hotter. I think you'd run out of fuel before anything catastrophic happens to the pump, but I think over time damage is caused by all of the hot/cold cycling. Hopefully it's the LPFP that croaks first since that's cheaper and easier to replace than the HPFP.
My advice is don't needlessly drive around with 1/4th of a tank of fuel or less; make it a habit to fill up before then. This is even more important for diesels and in winter, as it helps prevent running out of fuel at the worst time and aids in preventing fuel gelling.
After a certain temp pre-determined by the ECU and detected by the fuel temp sensor, the ECU begins to retard timing which results in decreased power. At the same time, the fuel pump itself is getting hotter. I think you'd run out of fuel before anything catastrophic happens to the pump, but I think over time damage is caused by all of the hot/cold cycling. Hopefully it's the LPFP that croaks first since that's cheaper and easier to replace than the HPFP.
My advice is don't needlessly drive around with 1/4th of a tank of fuel or less; make it a habit to fill up before then. This is even more important for diesels and in winter, as it helps prevent running out of fuel at the worst time and aids in preventing fuel gelling.
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05-25-2024, 01:55 AM
#8
Naturally, it's more desirable to have a less expensive part fail (LPFP) but the HPFP is not really part of the equation, in regard to the low fuel level in the fuel tank scenario, as it's not electrically-driven and is not cooled by being surrounded by fuel.
