99 Tahoe Fuel pump woes

[MO Viet Vet]

From another forum: Tahoe/Yukon Forum 99 Tahoe with fuel pump problems

"was driving on the long island expressway today at about 65 mph and my fuel pump quit (i think. but i will get to that) i pull off and go to check the fuel pressure. i don't have a gauge so i just poke the schrader valve by the firewall to see if fuel comes out. it just dribbles out with no pressure. so i tow the truck home ( with a Nissan altima. that was a white knuckle ride!) and drop the tank and swap out the pump. fast forward 3 hours later the truck drops dead again. same issue no pressure in the fuel line. it is extremely cold and im thinking this may be a factor? basically im wondering if their is any reason that this would happen again the same day. could it be the cold? some other problem? or do i just have the worst luck in the world."

Told him to get pressure readings and be aware of injector bleed off and maybe fuel relay problems.


"thanks for the wisdom im going to check the pressure and verify its good (or bad) and verify that i have proper ignition function. also another note when i did the schrader test it was with the pump on (key in the run positon) im not sure if that makes a difference"

Told him it did make a difference but still need pressure readings.

"Yep both times it died i tested it with the key in the run position. my assumpion was with the key on it should have hAd 60psi when i opened it up but both times it was almost nothing

---------- Post added at 12:11 AM ---------- Previous post was at 12:09 AM ----------

it wont even start so checking it when it stalls again isnt an option.

---------- Post added at 12:12 AM ---------- Previous post was at 12:11 AM ----------

im still going to get a pressure gauge on it but im positive the reading is going to be 0

---------- Post added at 12:14 AM ---------- Previous post was at 12:12 AM ----------

im thinking maybe i have crustys in my gas tank that is killing these pumps. when i did the first pump the sock had some nasty stuff wedged in it"

Then he installed another pump.

"the fuel pressure is 35 psi while cranking and when the key is first put in the on postion. its on the third fuel pump. every time a new one is installed it runs but shortly after it dies. i am at a loss."


That would have to be the worst inside tank problem I have ever seen. Any ideas?

 

[bladenbullet]

I have to believe crusties in the tank would be showing up on the screen if there was enough to kill the pump...a new pump isn't going succumb that quickly...it would be a visible problem if it did...the sock would look like a chia pet...I know he said the first sock was dirty but didn't mention it the second time...


bleeding injectors would more than likely lead to starting concerns and possible rough running when it is running....he isn't complaining about extended cranking or rough running....just quitting...

I would be looking for an electrical concern...we have a vehicle with some years on it and may have unwanted resistance in a fuel pump circuit that heats up and takes away enough voltage to kill the pump...

I am assuming he has replaced the filter and eliminated that as a concern...

careful examination of the electrical system and a voltage drop at the pump to determine that it is getting and using all 12 volts...if not hes got some detective work to do...the electrical integrity has to be there before moving on to any other concern...

I had a similar problem with a vehicle when I was with Saturn and ended up refunding a pile of money to a customer when we found a wiring problem the tech overlooked...they would have paid the bill willingly but right is right...

 

[MO Viet Vet]

Yea, I told him the injector bleed may only be related to the initial no pressure when he first checked the shrader valve but not bad enough for running or starting problems because he only complained of it dying and then no restart. I assumed since he didn't say each sock looked bad that they were not like the first one. I recommended checking the relay but also warned of typically when a fuel pump or circuit goes south they cough and gag instead of shut off like a light switch. I didn't copy and paste all of it for time sake. I did just ask him if it started ok on the first new pump and then died and asked if it ever started again with the third pump.

 

[bladenbullet]

fuel injected vehicles will die with immediacy if the fuel pump loses power....the pressure bleed off is very rapid and will happen with absolutely no warning...the volume of the system is so small that it has no residual pressure value....pop a fuel pump relay out sometime while an engine is running and youll find the stall immediate..even at idle there is not enough volume available to keep the pressure up for short term running...a pressure gauge will drop to zero very rapidly...the rerciprocal of this being how quickly pressure comes up when the pump is engaged at startup....

 

[lesterl]

New fuel pump modules for these normally come with a new wire harness connector, and for a good reason. Did he replace the whole module or just the pump motor? If so were the intank wires replaced?

Check frame ground for the fuel pump both at the fuel pump and perhaps the battery to frame connections...

 

[rockenthebowtie]

Lesterl. Whats happening ? Hope all is well ?. Its been a while ?

 

[MO Viet Vet]

see. friends that are sharp get to see each other again. I love it.

 

[lesterl]

Rocken, pretty much hang out in this forum as I only own a GMT400 style.......