Learned something new yesterday about fuel pumps

[gm280]

Long story as short as I can make it. My fuel pump stopped working on my '98 Blazer. Oh yes it is in the tank and could have gone out a week ago before I filled the tank, but not so lucky. After doing some creative siphons into empty gas cans and such (being how I filled my Ranger truck tank and gas can and everything up the day before) I finally got the tank out. And removing the cartridge type fuel pump assembly, I discovered the sender unit for the gas gauge was submerged in gas all the time with open contacts and wiper. That amazed me thinking how a voltage could/IS going through the circuit and a wiper too without any fear of spark or setting the tank ablaze (explosion). I would have never thought it was setup that way in all my life. Learned something new, but not an easy thing to discard... ray2: :nevreness:

Interestingly enough that sender unit uses the same ohmage sweep as most boat senders and guage units do....Hummm... :decision:

 

[Scott Danforth]

Re: Learned something new yesterday about fuel pumps

yep, GM gauge specs. think about it, where does your boat motor come from?

 

[gm280]

Re: Learned something new yesterday about fuel pumps

Scott, actually my OB came from Johnson, but since the ohmage swipe is the same, I can use it in my top side tank to my in dash gauge really easy. The part I was amazed at was the fact that an open circuit assembly was actually in the gas with live voltage flowing through it all the times. And the wiper arm swipes trough its range without and spark... Kind of scary if you think about it. I know the actual current is minimal, but still any voltage can spark as the contracts get closer together before actual contact. That was my learned lesson for yesterday. Scary as it my be, it is a learned lesson all the same...

 

[Scott Danforth]

Re: Learned something new yesterday about fuel pumps

regarding gauges, there are generally 6 resistance values in the world, most are moving to the "Standard Aftermarket"


0-30 Ohms (GM Type '64 and earlier)
0-90 Ohms (GM Type '66 and later)
75-10 Ohms (Ford Type '86 and earlier)
16-158 Ohms (Ford Type '87 and later)
90-0 Ohms (Toyota and Nissan '85 and later)
240-33 Ohms (Standard Aftermarket)


since the atmosphere in the tank is way too rich for combustion, the wiper arm has been that way since the beginning of electric fuel gauges.

now, if you were to pump in some oxygen, then we could have issues.

you realize you focused on the fuel sender and didnt even blink at the thought of the high current DC pump that is submerged in fuel with crappy crimp connectors at the top of the fuel sender? bet your look is now like

 

[gm280]

Re: Learned something new yesterday about fuel pumps

regarding gauges, there are generally 6 resistance values in the world, most are moving to the "Standard Aftermarket"


0-30 Ohms (GM Type '64 and earlier)
0-90 Ohms (GM Type '66 and later)
75-10 Ohms (Ford Type '86 and earlier)
16-158 Ohms (Ford Type '87 and later)
90-0 Ohms (Toyota and Nissan '85 and later)
240-33 Ohms (Standard Aftermarket)


since the atmosphere in the tank is way too rich for combustion, the wiper arm has been that way since the beginning of electric fuel gauges.

now, if you were to pump in some oxygen, then we could have issues.

you realize you focused on the fuel sender and didnt even blink at the thought of the high current DC pump that is submerged in fuel with crappy crimp connectors at the top of the fuel sender? bet your look is now like

Actually I was really surprised about how the entire pump assembly was assembled, a few plug in connectors and open wires. And I did contemplate the pump itself. I have taken everything apart, why? Because I can! And I love seeing how everything works, on in this case doesn't work. I have a new one coming in and those puppies are not cheap either. I was also amazed how really clean the inside of the tank is too. I was figuring lots of crap and junk in there. But it was near spotless. Also interesting is that little pump capable of over 100 PSI at 55 GPH rating.

 

[Scott Danforth]

Re: Learned something new yesterday about fuel pumps

you picked up the whole $300 module with the fuel pump, pickup, etc. correct? Just the pump alone is about $70 its the whole module that costs money. i normally attempt to unsnap just the pump and replace that if I can on my vehicles.

 

[Grub54891]

Re: Learned something new yesterday about fuel pumps

Ya, I took one apart also,the fuel on that one actually went through the electric moter. Think airplanes,same systym.......

 

[gm280]

Re: Learned something new yesterday about fuel pumps

you picked up the whole $300 module with the fuel pump, pickup, etc. correct? Just the pump alone is about $70 its the whole module that costs money. i normally attempt to unsnap just the pump and replace that if I can on my vehicles.

Yes I purchased the entire assembly thinking it is already 16 years old so everything gets replaced... First fuel pump in a tank that I ever replaced. I'm old school with the old mechanical fuel pumps running of the cam lode at the front of the engine and could be bought for a mere $19.95 at most any auto parts store...even some 7-11 places too. So this was a first for me. Not as bad as I originally figured either.
Just struck me as a bit scary to see the open wires and fuel level sensor/sender sitting in the gas itself... I guess it works perfectly safe being how we don't see vehicles disappearing daily from tank explosions...

 

[CharlieB]

Re: Learned something new yesterday about fuel pumps

you picked up the whole $300 module with the fuel pump, pickup, etc. correct? Just the pump alone is about $70 its the whole module that costs money. i normally attempt to unsnap just the pump and replace that if I can on my vehicles.

With two Blazers, two Astro's and my S-10 in the family I order just the pump from eBay for $23 and change them.

No need for the $$$ assembly if the fuel gauge is working fine.

I try to keep a spare pump on the shelf, they can go anytime after about 60K. Sooner if you're like my wife and hardly keep any fuel in at all. The pump runs much cooler, and longer when it is well submerged. She's killed 3 so far in her van. But that van doesn't use the same cartridge assy, that didn't come out til about 98. Her van is a 96AWD.

Don't you wish that women would LISTEN?

 

[CharlieB]

Re: Learned something new yesterday about fuel pumps

Oh, the last AC Delco pump I ordered for over $50 was 'Made in China' clear as day on the box. I was P.O.'d.

The exact same Chinese pumps I WAS ordering from eBay for $23

 

[bigdee]

Re: Learned something new yesterday about fuel pumps

since the atmosphere in the tank is way too rich for combustion, the wiper arm has been that way since the beginning of electric fuel gauges.

now, if you were to pump in some oxygen, then we could have issues.

you realize you focused on the fuel sender and didnt even blink at the thought of the high current DC pump that is submerged in fuel with crappy crimp connectors at the top of the fuel sender? bet your look is now like

Reminds me of when I was in the Army we stored gas in 55 gallons drums. We used to drop lighted matches through the bung hole and watch them go out as soon as they entered the drum....and bystanders would run like He!!