Fuel Pump Question

[RAMurphy]

Wow, I'm so far gone and asleep at midnight. I'm more likely to start this job at 0600. I'm hoping this job will go smoothly.

 

[iamdub]

The sump area that you are referring to is only so tall and if you look at the fuel pump placement in the module you will see that a tank(sump) can be ran low enough to still have well less than a gallon of fuel in the tank (sump) but not totally cover up the fuel pump. The fump does not lay horizontally in the bottom of the sump. You are right in that it is unlikely to suck up much "trash" because of the sock filter but even the sock filter will only stop a certain size of particles. Granted they screen on the sock is very fine.

You could be also referring to that odd looking black cozy that wraps around the pump itself? Ive never seen one of those that actually hold anything other than the pump and I believe those are just for getting rid of vibration so its a dampener.

I still maintain that the pump is fine in 1/16 tank level and even less.

The pump is cooled by the fuel it is sucking up and passing through it. It is always pulling fuel through it regardless of the tank level because it pulls from the bottom of a relatively small bucket (sump). It pulls considerably more volume than it needs to pressurize the system even with the injectors at a high duty cycle. The excess fuel volume (not that returned by the system pressure regulator) keeps the bucket filled. The pump is about as low as it could possibly be in that bucket. The tank would need maybe about an inch of depth of fuel in it before the pump couldn't suck any up to pressurize the system and fill the bucket. It'd probably run on less than an inch if it were sitting still. Accelerating with such low volume would cause fuel starvation when the fuel sloches to the rear of the tank. Yes, that isolator (the black Koozie thing) is for sound and vibration dampening cuz the pump motors are LOUD.

 

[RAMurphy]

Well, I just completed my fuel pump change. What a major PITA. First one strap bolt was so rusted, it took so much PP blaster and an overnight soaking before I eventually broke it loose - literally. Dropped the tank, and that SOB fuel pump hold down ring was so rusted and would not budge. Another several soakings of PP Blaster and setting overnight, a pneumatic air needle/flat chisel to break the rust and finally a good number of very hard hits with a hammer and she broke free. Tank pins still in very good shape. Believe it or not the install was just as hard. The new ring and gasket just wouldn't seat. Finally got it to seat, went to plug in the four prong electrical connector and it would not seat. Ended up taking the pump out to do some troubleshooting. My fault, I should have checked before I installed it but I found one pin slightly, but just enough, out of alignment. Not sure how that happened, but a painful lesson learned. Put it all back together and she started right up. I will tackle the evap charcoal cannister another weekend.

 

[2006Tahoe2WD]

Well, I just completed my fuel pump change. What a major PITA. First one strap bolt was so rusted, it took so much PP blaster and an overnight soaking before I eventually broke it loose - literally. Dropped the tank, and that SOB fuel pump hold down ring was so rusted and would not budge. Another several soakings of PP Blaster and setting overnight, a pneumatic air needle/flat chisel to break the rust and finally a good number of very hard hits with a hammer and she broke free. Tank pins still in very good shape. Believe it or not the install was just as hard. The new ring and gasket just wouldn't seat. Finally got it to seat, went to plug in the four prong electrical connector and it would not seat. Ended up taking the pump out to do some troubleshooting. My fault, I should have checked before I installed it but I found one pin slightly, but just enough, out of alignment. Not sure how that happened, but a painful lesson learned. Put it all back together and she started right up. I will tackle the evap charcoal cannister another weekend.

Good work. Now you are the expert for the rest of us.

 

[iamdub]

Lol @ "PP Blaster". Sounds like something a 6 year-old would say

 

[RAMurphy]

Well, I'm 60+ years old so thank you for the compliment. PP or PB - call it old timers or some timers or quite frankly fat fingers. But I can tell there were a few (ok more than a few, I did spend a career in the Navy) choice words during this entire R and R.

 

[iamdub]

Well, I'm 60+ years old so thank you for the compliment. PP or PB - call it old timers or some timers or quite frankly fat fingers. But I can tell there were a few (ok more than a few, I did spend a career in the Navy) choice words during this entire R and R.

Don't get offended, sir. Anything with "PP" in it is funny.

 

[RAMurphy]

Not offended in anyway. You actually cracked me up.

 

[RAMurphy]

Well the beast is still running strong. Put 500 miles on this new pump, I think I'm good. Hope to tackle the evap cannister this weekend.