nearly stalling after sitting for a couple days

[yup]

after my 99 tahoe sits for a couple of days it sputters for about 20ft then runs fine. The sputtering is relatively intense, kind of like a clogged fuel filter. restarting throughout the day is fine though so thats why i dont think it s the filter. everything is normal other than those few seconds at start up, you wouldn't even know there is a problem. No engine light either. could this be a fuel pump issue?

Thanks for the help.

 

[SunlitComet]

measure the pressure when this happens to see what is happening.

 

[pcbcadman]

My 2003 LT 5.3 Tahoe is doing the same thing, but it continues for a few minutes. My fuel pressure is 50 psi. The spec says that it should be 55 to 61 psi. Do you think this close to the spec would cause this? I have a mechanic friend that thinks it could be a check valve leaking, but wasn't sure this fuel pump has one. Can any speak to this? I assume this may be a sign that the pump is weakening or not? Mine acts like it is starving for gas... Thanks, Johnny

 

[laredo1307]

Check under your distributor cap. You might be getting some corrosion build-up.

 

[SunlitComet]

how much pressure do you read on the fuel rail after one minute of the pump turning off?

 

[pcbcadman]

About 43 lbs. of pressure after one minute of the pump turning off. About 40 lbs. after an hour. When switch is first turned on it is 50 lbs. As soon as you start the engine it goes to 45 lbs. I understand the spec for this Tahoe (2003 Flex fuel - 5.3) is suppose to be 55 to 61. Do you think this is enough out of spec. to cause this problem? It has 113K miles and the pump nor the regulator has ever been changed. Fuel filter was changed about 18 months ago or (15K miles). it only acts up first thing in the morning when you first crank it up. Acts like it's starving for gas, then after a couple of minutes it runs fine. I am just wondering if this is a precursor to the pump dying on me.

 

[SunlitComet]

well the pump seem to hold static pressure just fine. what happens to pressure if you crack to wot? also running gas or ethanol?

 

[pcbcadman]

What is "crack to wot"? I am running gas... This problem reminds me too of an old big block chevy that I had that vapor locked years ago.

 

[SunlitComet]

crack the throttle to wide open for a moment.

 

[pcbcadman]

Looks like it actually goes up to about 52 lbs. (crack to wot).

 

[SunlitComet]

that seems a bit low on wot. i would test your pressure regulator with a hand vacuum pump to see if it is the issue before replacing the pump.

---------- Post added at 11:53 AM ---------- Previous post was at 11:53 AM ----------

tho ironically those number seem right when running ethanol.

---------- Post added at 12:10 PM ---------- Previous post was at 11:53 AM ----------

you know what before going any further give me the vin character for your engine. either v, t, u or z and it will be the eighth digit from the beginning.

 

[ccapehartusarmyINF.(ret)]

its always the fuel pump, when i was checking to see if GM has a recall on my vehicle i found an old recall on GM fuel pumps just about 80 percent of this forum including me has had to change out the fuel pump

 

[SunlitComet]

tsb number please before we say every pump in the tahoe is a turd.

 

[yup]

I replaced the fuel filter and cleaned the MAF sensor and that seemed to fix it.

 

[SunlitComet]

what are your pressure reading now?

 

[pcbcadman]

I just replaced the fuel pressure regulator, but is still starves for gas when it's cold.

 

[SunlitComet]

if that included a filter recently then either injectors are acting up or the pump is not strong enough. do you have a test procedure for the entire fuel system? i might have one around here.