have a '98 Blazer with about 180k on it. While I suspect a fuel problem, not sure it's a pressure issue. I replaced the filter.

when driving down the highway about 60-70mph just in the throttle to keep it at speed it runs great, when you tip in to the throttle approaching 1/2 throttle and beyond it will lay over act like it aint getting fuel. Whne you back off the throttle to obtain the 60-70mph speed it will run fine.

i put a gauge on it and when cranking the vehicle it goes to 50psi. when you rev it up it goes to 60ish.
i let it sit over night and it would not start, i cycled the key 6-8 times and it still didnt start, i poored gas in the throttle body and ti started and runs fine at idle and when you rev it up to 2500 its ok and then if you rev it real hard it will hesitate.

if you try to power brake it it will go to 2500-2700rpms and then as you approach Wide open throttle it lays over and no power.


put vehicle on tech2 and maf,o2,throttle position all looked good and there are no mis-fire codes.


im LOST

thanks for any help

 

96+ Fuel System Diagnosis

Also, check the catalytic converter, it may be plugged up and make sure the EGR valve is clean.

 

i will check them out also.
im at wits end with this thing

 

Did you observe the TPS sensor output all the way from closed throttle up to WOT throttle? Were there any drop outs?

How were the MAP sensor readings?

 

the tps was good

 

are you sure the fuel pump is holding pressure?

 

i put a fuel pump in it and its working great....so far