about fuel pumps...My fuel pump in my '99 jimmy, (4 door), apparently seems to be on its way out. After running it without so much as a sputter, it just plain refused to start. The pump wasnt priming, and there was no pressure at the fuel rail. (I ended up taking my car camping instead). So...the jimmy sat in the driveway all weekend, today i figured i would make a move to replace the pump, i picked up a new delphi pump...but just to make sure, i jumped up and down on the side rail to shake the gas tank. Lo and behold, when i put the key in, the pump primed and the vehicle started without so much as a hesitation, (it has now been idling in the driveway for more than a half hour without an issue).

I should add, that i had some fuel line cleaner in the tank as well, and had been running it for awhile like that, (i had added it to a full tank).

So my question is this: is it possible that perhaps there was a buildup inside the pump that caused it to seize, that may have disolved or dislodged when i shook the vehicle? and should i continue with my plan to replace the fuel pump? (my fuel pressures are all within the nominal range)

*and i am not getting any trouble codes, or even the CEL

 

i would say change it when they are dead there dead sometime hitting the bottom of the tank or letting them sit sometimes makes them work but put it in drive and try going around the black it will prob crap out again.

 

i did take it for a drive, after letting it idle for like 30 mins, drove fine, like nothing ever happened. Have restarted it a couple times too, every single time, the pump primes fine, (no exessive noise, proper fuel pressure)...

The only reason i ask these questions is because i could REALLY use the money back from the new pump, and the jimmy isnt currently my daily driver, (im just trying to resurrect it)

 

idk usually when they die there dead an that's it

 

Phil my 99 acts similar but it is getting worse. Im about to change my fuel pump as well. Sounds like you should be good for a little while. I use a little mmo to clean up the fuel system.

 

my 01 was doing same thing changed pump and guess what it did it again turned out to be bad regulator in plenum guess it was causing computer to shut down pump did the multiport conversion and its been great

 

From my experience. Most earlier model vehicles do not have Fuel Pump
related OBD I nor OBD II diagnostic's / codes built into the design of
the vehicle.

The intermittant Fuel Pump issue the OP posted could possibly be
Fuel Pump Relay related. I would double check the Fuel Pump Relay
voltages and/or purchase a spare relay just in case . . .
you may clean the Relay's contacts too as a safe measure.

Most vehicles similar to a Blazer will have a Fuel Pump bypass / test wire connection jumper point - most likely in the Engine Compartment.
The actual Fuel Pump Relay is most likely under or behind the
Glove Box along with other Relay's.

 

X2
Fuel Pump will sometimes show some signs of near Death (a few days only) before it Dies. When it Dies It Dies.

 

Thank you all for the replies, I will definitely check the relays, (i tried the pump prime jumper when it died, and i got no response from the pump), and will look into the multiport conversion...

In the meantime i will keep the pump near by, and patiently wait for the current one to fail

 

Check your grounds and connecting jacks. Take them apart and clean with contact cleaner. Also check your oil pressure sending unit as the pump runs by a series connection thru fuel pump relay-oil pressure sending.Good luck