Am I right to blame the fuel pump?

[Biscuitman]

Just bought a 94 Q45. I recently changed the spark plug and this site was very informative and accurate. My problem I have is sometimes when I take off from a red light the car runs really sluggish. I can hear what sounds like back fire coming from underneath. Once getting up to cruise speed (30+) the powerband kicks in and off I go. This is not a every time thing and if I manual shift the transmission I don't have this problem, I know my fuel pump sometimes hums and sometimes don't which is a warning to replace. My question, is the fuel pump to blame for the lack of power/bucking and popping noise, or is something else causing this? I will be replacing the fuel pump soon. Thanks

[BCC93QT]

Probably the MAF. Could be the FPCU. Maybe the fuel pump,- does it sound like a beehive in the trunk when you start it up?

[Biscuitman]

does it sound like a beehive in the trunk when you start it up?

It's an off and on thing but it is becoming more frequent.

[N/A Q45]

Usually if you're going to run out of fuel from a bad fuel pump it will get much worse as the demand increases ( higher rpm )

And you're saying that if you come to a complete stop and floor it in D4 it only does it then? Not when you stop and shift it yourself?

Like BCC93QT said there is a pretty good chance it's the maf/ connector. I know I don't run the stock Q45 maf sensor as it would just out of nowhere cause the car to run full rich (wide bands were reading 10.0 which is as low as they can go) the maf even tested 100% but it still did it when everthing was the ohms it should be. So yours might be starting what mine did. I now run a e60 sensor which are a dime a dozen but need a tune/ hell the stock setup needs a tune bad.

[Biscuitman]

I have no problem shifting myself, just wanting to know the cause of this problem. And it's not being floored, just normal driving conditions.

[N/A Q45]

Very small vac leak would be my only other guess.