fuel pump AHHH problem!! ahhh

[mark]

ok heres the problem. a couple months ago, my car started having starting problems and also was shaking a bit while at a red light. i took it to a machanic and was charged 40 bucks just so the **** can tell me that the fuel pump was only getting 75% of the fuel (he was a **** because my mom did business with him for years and always was nice to him and paid him cash meanwhile he quoted me 20 for the inspection and charged me 40 and even had the guts to add tax. but thats irrelavent) so i took out the old fuel pump and replaced it with one that i got off some other crocked machanic from a 240sx 1990 parts car. that stopped the starting and the shaking problem for 1 day but then it went back to both. then i bought one off ebay and that was worse than the one i had now? is it possible that all 3 fuel pumps are duds? or can it be something else in my car like injectors (whatever that is) thats causing the problem. Also am i installing the fuel pump right? there are 2 pipes going down. one connects to the pump, on just goes to the gas, and then theres a tube from the pump with a small filter at the tip which goes down to the gas as well. Please help or i will have to sell my 240 and get another one because i wanna soup it up but cant soup up a car that has shaking and starting problems.

thanks,marcus ([email protected])

[SWIFT_DRIFT]

Having starting and idling problems (shaking)...have you checked your spark plugs, wires, distributor, and timing? All of those could lead to the same starting and shaking problems.

[mark]

i replaced my spark plugs, it could be the timing. anyways i can check this myself or do i gotta take it to my machanic?