98lswonz28

this problem just blows my mind.

heres the scoop... The truck is a 99 and will run fine untill this problem occurs, usually 2-3 times a week after driving 10 min. When I slow to a stop the truck will bog(rpm gets low) like 300 or so rpms, and I have to give it gas to keep it alive, when I do that it stumbles as if its either got a missfire or loaded up with fuel. once I get the rpm up above 1200 or so its fine, but if I let off the throttle it will bogg back down. no I will drive like this for about 5 more minutes and the problem will go away... till the next time it does it. and in the 5 minute window where its messing up I only notice it when I slow to a stop.... another thing.. the fuel gauge will move down while this problem occurs and then back up... Ive put a new air filter in it, cleaned the maf and the throttle body and no change. Ive bought a fuel filter but havent put it on yet.



ALSO, NO CODE HAS BEEN THROWN

This problem just doesnt make sence to me. it only happens under 1k rpms.


any help with be awesome, I just got back from Iraq and will be driving from washington to texas in 7 days.

things I think it might be..... Fuel pump, wires, plugs, filter, tune. crank sensor, cam sensor..

SLP4CamaroSS

iTrader: (16)

vacum leak?????

STRIPSTAR

iTrader: (4)

yeah, vacuum leak is possible but since its so intermitent my guess is plug wire or trash in fuel filter. Change the fuel filter and plugs for good measure and then see if it acts up.

98lswonz28

no vacume leaks, filter will be replaced today although I am almost positive that that is not the problem. I just read also that many 1999-00 gm vehicles have problems with the irratic fuel gauge. I pulled the coil pack plug ins one by one and the truck stumbled on each one, so im thinking its not ignition.

98lswonz28

just read that the fuel pressure regulator was the culprit on many 1999 owners having the same problems.

ill keep yall posted

00_STANG_KILLER

Clean the throttle body out there is a TSB for this problem and i get them in the shop all the time for the same problem. Take ur intak boot off and spray carb cleaner in the throttle body real good and wipe it out with a clean rag.....

ArcticZ28

iTrader: (14)

Don't overlook the MAP sensor/hose. Same thing happened to me intermittently and it turned out that the hose to the MAP had dry rotted enough to cause this.

98lswonz28

The problem seems to have been fixed by cleaning the fuel pressure regulator out with carb cleaner, hasnt acted up in 3 days.

where is the map sensor located at on the 5.3. I know lt1s, just getting into ls motors


also the maf and throttle body were cleaned with carb cleaner.

GMTECH4

almost sounds like something electrical to me when u said that the gas gage drops. this might sound crazy but try banging on the gas tank with the truck running and see if the engine bogs also try shaking the wires/harness on the fuel pump. you may have resistance somewhere.

BerryWS6

iTrader: (9)

I have one for you, I kinda had the same problem and it turned out to be the coolant temp sensor. it was malfunctioning and telling the computer that the coolant was 80* instead of 210*(or so) and was running so rich it was flooding it till it would want to die. the truck ran fine in open loop then when it ran in closed loop it would start this.

jimmyblue

iTrader: (11)

I also had a bad ECT sensor connector on a '99 5.3 truck
that really flaked it out. Pull & reseat, all better.

98lswonz28

thanks for all the help guys, It did act up the day before I left. Ran fine the whole 2600 mile trip and hasnt acted up since the 19th of sept, now its dec 28th.