when i smash down the gas to the floor on my 1999 jimmy 4x4 it will kickdown and rev up to 3000 rpm then sputter. if i let off of it to 3/4 it will rev up and the shift. any one have any ideas on what could be causing this. i have replaced the fuel pump and filter and i use slick 50 fuel system treatment every third tank i am deff. open to sugestions!!:banghead:

Have you checked for an exhaust restriction?

it has a flowmaster exhaust and no cat

OK, ...but have you checked for a restriction?

i did but i couldn't find anything that was causing it to have excessive back pressure. could it be due to a lack of fuel, and if so what should i look for?

Check/replace fuel filter. Check fuel pressure: key on, engine off, pump running, pressure must be 60 to 66psi. After the pump shuts off, pressure must remain above 55psi for 3 to 5 minutes.

i will check that out, but the ? is if the pressure is too low what may be the cause? i just replaced the filter like two months ago.

It could be the fuel pump, fuel pressure regulator. I though, would be betting on the pump.

the fuel pump was replaced about 10 months ago.

the fuel pump was replaced about 10 months ago.


Just because it's new, is no guarantee that it's good. Check the pressure and leakdown rate to make sure it's within specs.

Hi,
I'm just curious if you found your problem??? Mine has been doing the same thing off and on for a few months. It's like it's clogging up, but after it runs through it's problem for a few minutes then it's fine for a few more days???

hey I read about your problem i was having the same problem you are everytime i tried to floor my '96 blazer. my blazer would hesitate and sputter as if it wanted to die out.as i fooled around i came across my intake hose, behind the mass air intake sensor. i noticed it had a crack under the bottom of it. The crack was seamingly unnoticeable and out of sight.Not thinking it was the cause i simply tapped it up and placed it back on,,afterwards i started my truck put it in drive and what do you know,,, it burnt rubber lol such a little problem quite possibly this may be your same problem