New fuel pump fixed it

[LaGrasta]

My aftermarket pump is only 25k old. The van starts and runs great, until it doesn't. After we take a quick run or two, stop shortly; it won't start until we wait 10-15 minutes. I suspected a few items, but it turned out, it was the fuel pump. I spent $300 and bought an ACDelco this time, hoping to never swap another pump ever again.
Posting this in hopes of helping another. Roll on!

[Herbie]

Good confirmation.

Conventional wisdom seems to be to stick to the ACDelco pumps, and there's mounting evidence that this is valid. I haven't swapped mine yet, but I've got an ACD sitting in the box waiting for the moment.

[Astrophysics]

Hi,

My 2003 Astro AWD has 136,000 miles on original fuel pump.
Last week it did the start and die immediately routine a few times. Then it would crank but not start.

Check all fuses and FP relay. Cleaned Ground bolt and ring terminal at radiator support, and at G302 on frame new fuel tank.
While I had the G302 ground ring disconnected, and fuel pump relay removed, I measure resistance of wiring and pump windings to be about 1,150 ohms on my Fluke77 DMM. G302 ring to pin 30 of FP relay .

Since typical GM fuel pump draws about 7.5 amps to run, using ohms law, R= V/I = 12 v/ 7.% amps = abot 2 ohms.

I will open wire bundle to look for bad wire. Or I suppose pump motor brushes finally got lots of carbon and raised resistance.
But I have never run out of gas and usually fill up with 17 gallons which means a few gallons still in tank to cool the FP.

Merry Christmas

AP

[MountainManJoe]

A meter can tell you if a winding is broken.
But I don't think you can use Ohm's law to calculate power consumption on inductive loads such as motors.

[Astrophysics]

Hi,

This is a DC brushed type motor used in fuel pump. The fuse value of 20 amps for FP circuit means the expected current is in the neighborhood of 10 amps which gives some margin on fuse value.

Yes, the winding resistance would be used to estimate expected current draw.

With such a high resistance in the wiring, it could be a corroded contact . Copper wire of 14 AWG or metric equivalent 2 square millimeters cross sectional area has maybe 10 millohm per foot or copper loss. Allow 20 feet of total wire from relay in engine compartment to pump in gas tank. Wire resistance should be low.

I did try connecting a 10 amp DC amp meter in series with the 12 V feed to the pump but no appreciable current flow due to high R in circuit.

AP

[MountainManJoe]

Yes, the winding resistance would be used to estimate expected current draw.

Resistance would just tell you the stall current (which would eventually burn the motor out), Expected operating current is much lower.