hello! i tried to search the forum for my problem with no luck so i am trying a new post...

i have an '89 burb, 4 wheel drive, auto trans, 5.7. in short, my problem is it will idle just fine, however, when in drive, or under a load, it acts as if it is not getting fuel. sputters, spurts, hesitates. i can force it to go, although slowly but i cannot get it up to speed. i'm stumped because it runs sweet at idle! it has had recent tune up. today swapped out o2 sensor and manifold intake gasket. still nothing. what would cause it to act so poorly when the fuel pedal is pressed? please help asap... i am running out of ideas! oh, it gives me codes 44 and 45... lean fuel and rich fuel. ugh!
thanks
heather

 

Welcome to the forum.

Check your fuel pressure.

 

Welcome to the forum.

I'm moving to the S-10 section.

 

tps sensor could have a fault in it which is why you get no action when you push the gas pedal.

 

I agree with RacerX, I would suspect the Throttle Position Sensor....

 

many thanks! i will try the tps next. and check the fuel pressure. do you need 2 people to check the pressure? i am usually here alone but could fetch the neighbor if needed. i forgot to mention this problem came on gradually, not suddenly. over a period of about a month or so, maybe 2? started out mild (like hesitating slightly at acceleration) and graduated to being undriveable (though it still starts and runs at idle just fine.) please no lectures on driving it with a problem... i absolutely must go to work! i have checked the vacume lines visually, but honestly, i can tell when they need to be changed and thats about it. i don't know what they all do or where they all go. i think i can hear a vacume leak when i'm in the cab that gets higher in pitch when i give it fuel. there is a black, round diaphram thing on the firewall behind the distributer... what does that do? it is suspect because i unplugged the lines from it to check the ends and the next time i started it it seemed to run a lot better for a few minutes.

i'm sorry this is long... i'm broke and running out of things to try and get my rig back on the road! i will post back if i have any luck! thank you
-heather

 

is the sensor one that can be cleaned or will it have to be replaced to find out if it is the problem? i know that sounds dumb but i have to be frugal!

 

sheesh, one more question... if the fuel pressure is low does that mean i need a new fuel pump? that would be terrible.