Ok guys....now I need your help...

When I try to accelerate with more than about 25% throttle, the car lunges back and forth. It happens in any gear, at any RPM. If I accelerate with like 10% throttle, the car runs fine. When I pulled into my yard, I was hearing a loud humming/buzzing noise coming from the rear of the car which sounds like the fuel pump.

First, what do you guys think the problem is?

Second, what are symptoms of the fuel pump going out? Symptoms of the fuel filter being clogged?

Third, how long does the fuel pump usually last? The car has about 75k miles on it.

Thanks for any help guys.

I was told that after 50k miles most of my friends had to change alot of minor things...fuel pump might have been one of them. As far as I know Mitsubishis hold up pretty well its the little things that usually stop working...anyway probably not helpful but just some input

well....i let the car sit for about 4 hours and im no longer having the problem. i am going to take it by the dealership tuesday to have them check it.

Mittech....when doing the 60k service, aren't the technicians suppose to check the fuel system(fuel pump, lines, filter, injectors)?

They perform a visual inspection. The fuel filter is part of the fuel pump and does not get replaced as a maintenence item. I have seen some bad fuel umps but it is not a common problem normally the car wont start.Did your check engine light come on?

yeah the light has been on for a good while...i just thought it was b/c of the intake. the light would come on for like 3 days, then go off for like 3 days. but once this happened Sunday, i took it to advance auto to get the codes....and here they are..

P0171 - System too lean (Bank 1)
P0174 - System too lean (bank 2)
P0421 - Warm Up Catalyst below threshold(?)

so obviously the engine isnt getting enough fuel. i have been able to tell when its going to do it. if i drive for a good while, then it will start happening. if i let the car sit for a couple of hours, the problem goes away until the engine gets good and hot.

P0421


might have a bad cat....are the cats on the 3Gs on the manifolds???

there are 2 pre-cats and a main cat. the two precats are on the manifold

yeah, thats what I thought... might be a bad pre-cat, just going by that code though

is that code for bank one??

well this is a suggestion, prolly isnt it but it only takes five mi to check or less. Check to see if there are any holes or openings in your air filter, because if somhting is broken, then your suckingin rocks and stuff, whcih i did. What happened was when you tried to gun it or anything like that, it would be pulling in so much bad air it would cause the engine to shudder, since it was pulling in unburnable objects. If this is the case, replace it and run your enjine idle for about 5 minutes to clear any remainding particles out of it...

hope this is the problem, since its an easy fix

it turned out to be a bad cat. and im getting the work done for free. the dealership says the car is still under warranty.....even after 77k miles

hey, if the cat don't work, you might have a bad o-ring in the fuel line. that happened when i put my 255 in. it took two minths for mits to figure out what the problem was.

you had a bad o-ring b/c it was a faulty install of the fuel pump. thats one of the most common mistakes that is made when installing the Walboro fuel pump in the 3G. i haven't replaced my fuel pump, so it *shouldn't* be the problem.