Chevrolet Cruze ECO "returnless" variable pressure fuel pump

[user removed]

Another advantage is the fuel can absorb engine heat which improves atomization. In the return systems a lot of that heat was returned to the tank and over some time would warm it up measurably and, as previously mentioned, increase evap emissions, which are generally offset by reduced fuel delivery from the injectors.

regards
Mech

[Blue Angel]

Originally Posted by Old Mechanic

In the return systems a lot of that heat was returned to the tank...

Thanks for adding that! I realized I didn't put that in there after posting and was too lazy to add it.

[pete c]

The voltage to the FP on my '90 Toyota pickup (motorhome) varies. I assume that means it has the ability to vary pump power output. I think there is a return line, but, I'm not sure. Maybe Toyota was already doing this 23 years ago?

[WesternStarSCR]

Originally Posted by Blue Angel

Found this old thread and wanted to add some info.

The newer systems like the one in the Cruze use an intelligent driver to manipulate the fuel pump RPM to vary fuel pressure and flow as required. As far as I know, no pressure regulator is used so every bit of gas pumped by the fuel pump is required by the engine. It wouldn't surprise me if lots of vehicles are using this system by now.

I don't know how prevalent they are yet, but ther are coming soon.

An Electronics supplier showed me today, as an example about the power of Matlab software, a PWM ECM controlled variable speed fuel pump with feedback loop to maintain the exact pressure at all times.

On a sample Mini Cooper run through Matlab Simulink, baseline fuel pump was 95 watts constant. Variable speed was averaging in the 55 watt range. And a brushless variable speed was in the 30 watt range.

To convert to theoretical FE changes, more Matlab analysis indicated a 0.5% to 1.5% FE increase due to reduction in alternator load. They considered this low hanging fruit, even though it was small, but measurable, FE improvement.

[gone-ot]

Yep, every 746 Watts of electric "load" is another horsepower you're feeding gasoline to.

[britttolbert]

Originally Posted by gone-ot

...they're also touting their Regulated Voltage Control (RVC) system that is effectively an "on-demand only" field regulator system that holds battery voltage at ~ 12.3VDC instead of 14.7VDC all the time.

...instead, it only pumps the voltage up to 14.7VDC right after a heavy load (starting) then backs off to ~12.3VDC while cruising; but, goes back UP in alternator output voltage (if needed) during decelerations and breakings.

...good news for lamps and light bulbs, but not so good on batterys themselves.

After 8 years of owning a cruze with this system it has been so so on the bubs, it eats about 1-2 headlights per year but no other bulbs. Insofar as the battery, the OEM battery lasted 6 years. I too feared that the alternator would be hard on batteries but 6 years out of a battery these days isn't bad.

[samwichse]

Holy necro posting, batman!

[roosterk0031]

If you are buying you headlights at Walmart, stop they are only rated 150 hours. Go to rockauto or similar and get some Long Life bulbs for $6 each went with Hella's for the cobalts and Impala.. I finally started tracking when I replaced them and 150 hours is about it on the last one.

The impala also drops to low 12's a lot, asked when it was in for something else and they said it was normal.