Fuel pump PSI

[Mobiletec]

Will a Tech 2 scanner tell me my fuel pump pressure.

[Blue Bowtie]

No. There is no fuel pressure sensor, so the PCM has no idea of the pressure, therefore, it cannot report it. You'll need to connect a mechanical gauge.

[CD Smalley]

Now that his question is answered, that does beg another. Why not? Why isn't the fuel pressure reported to the ECM?

Oil pressure is reported. Air pressure in the tires are reported to quite a few new cars.

Why isn't the fuel pressure reported?

Just wondering...

[Leeann94astro]

No sensor, no PCM input from said missing sensor.

Not to mention, the fuel pressure changes so much - KOEO is one spec, leakdown another, running fluctuates madly depending on what you're doing.

[CD Smalley]

OK so the question is then "Why isn't there a sensor to report the fuel pressure?"

Oil pressure fluctuates as well. It would just be a matter of having a slower sensor or taking readings less often from the sensor and then reporting them to a gauge at a rate appropriate for humans to read.

[Blue Bowtie]

Perhaps the better question would be "Why?" The PCM couldn't do anything with the fuel pressure input anyway. It can't change the pressure, since that is a function of the pump and FPR. It already monitors four oxygen sensors, the crankshaft reluctor, cam position, throttle position, temperatures, and intake air rate and changes injector pulse width thousands of times per second to manage fuel mixture, rate, and sequence.

95% of drivers wouldn't have a clue anyway. It would only be useful as a diagnostic tool, just like a mechanical fuel pressure gauge.

[CD Smalley]

I was thinking about it from a purely diagnostic point of view too. It can't do anything with the oil pressure either... But it would be nice to hook up a scan tool as suggested and see what was reported and to get a trouble code if it saw too low of FP...

[Blue Bowtie]

Well that's just lazy...

It would be nice, though. There is already a pressure transducer in the transmission, and a high percentage of cars have a transducer for oil pressure just to operate a gauge. Connecting that to the PCM probably wouldn't be that difficult as a diagnostic tool. Installing a pressure sensor in the fuel line wouldn't be difficult, but would be another $100-200 per vehicle for something mostly unnecessary. Then again, On-Star, MP3 players, heated seats, automatic wipers, and all the other unnecessary things installed on cars and trucks likely cost a lot more, and are arguably even less useful.

[CD Smalley]

I admit to being lazy at times. But imagine the $$$ saved in not having to train a technician to read a manual, get a special tool out to check the FP. They could just plug in the scan tool they all have now and there it is. All the diagnostic work done for them.

[Earlyboomer]

This is kind of interesting in a way. Leeann and Bowtie have some good points. Since I just tried 3 fuel pressue gages to compare them and have seen some of the things you mention, maybe with these in tank fuel pumps, a pressure gage on the dashboard so you could keep an eye on how the pump is doing might not be a bad idea for us car nuts, like we keep an eye on the oil pressure. For the average driver it would no doubt be worthless just the like the oil pressure gage is to them. Factories would never install them. Lets see how much instrumentation factories start putting in electrics and hybrids. The voltage in these can be anywhere from 200 volts to over 600 volts, enough to easily electrocute, so would the average driver pay attention to a voltmeter gage? (I have a lot of electrical experience, so I don't want nothing to do with them.)