i have a 2000 blazer 4.3 4wd 4 door automatic my question is can a P0740 code stop the fuel pump from working. got a check engine light and two days later before i could get it to be scanned blazer started and shut back off. tried starting again with no luck. listened closer and didnt hear the fuel pump working. checked fuses-ok and can feel the fuel relay in the fuse box under the hood click when the key is turned. drained the fuel tank (syphone hose through the tank vent) to drop tank to change fuel pump. turned key on to see if i had all the gas out and heard the pump run. blazer started and i ran it for a minute grabed my code reader(just purchased to try and find the problem) hooked it up and got P0740 but i dont hear the pump run when the key is turned on. help

 

P0740 should not prevent the pump from working. Sounds like you may have a problem with the pump which is actually quite common. Since you can feel the fuel pump relay click, that would tend to rule out an ignition switch problem which can cause both codes (plus a host of others) to set.

 

thanks i will go on with dropping the fuel tank so i can check voltage to the pump before i buy a new pump ( i thought they would be cheaper on someting 11 years old). any ideas what might be giving me the p0740 code???????

 

Your pretty much going to have to diagnose it. It could be anything from a wiring problem to a failed solenoid in the transmission. A search for 'P0740' will turn up what others have done to diagnose & correct this code.

 

after checking voltages at fuel pump connector i was getting voltages so bought the new fuel pump installed it and it started right up (could hear the whir of the fuel pump real good ). i also noticed when i started it my key seem to stick a little in the crank position. when looking up p0740 post talked about the ignition sw.. does this sound possible like a symptom of the sw.(the code and sticking a bit) if so how hard is it to change????