Car is studdering/hesitating need HELP!

[Champz]

Hey guys, once again need some help from the zilvian community.

The car is nissan 240sx 91 w/ a ka24de. ill try to explain everything as much as possible, soo....

I just recently change out my whole fuel pump assembly cause it was rusted out. so i replaced everything and put it bak, everything was fine until the car starts studdering when in neutral, it will drop down to 500 rpm and starting studdering, until i have to hold the gas. sometimes when i make a complete stop, the car would just turn off. Even in 1st and 2nd a hesitation from the engine

I thought it could be a fuel filter, so i replaced it with 300zx one, still the same problem occurs.

If anybody can lead me to the right direction, it would be much appreciated since this car is my only car

thanks in advance
champz

[PhAtXSuMo]

check your maf or replace it... i cant think of anything else right now...

[eclipse_dsm]

Try cleaning your AIV better yet just take it off. this is a fairly common issue. I'm sure if you do some more searching you'll find it. GL!!

[buckaroo]

I would check for vacuum leaks, I've had many idle problems with my 240 and an integra and they turned out to be vacuum leaks. Spray like starting fluid or carb sray around and listen for engine to pick up.
Hope this may help:)

[crzycav86]

so it wasn't doing this before you changed your fuel pump? this should not be related....

[Champz]

the car was in storage over the winter for 4 months, before getting back on the road, i replaced the rust fuel pump assembly since it was leaking fuel. im going to clean the maf or replace it and start from there. whats the best way to clean it?

[Champz]

Thanks guys,

ya found the problem, it was one of the vacuum lines on the intake it was loose, causing me to idle badly, so got that fix and idling is good but the only problem now is when i shift in 2nd and when i accelerate fast the car starts to hesistate between 2-3rpm and the car rocks back and forth, but if i accelerate slowly no problems, any idea what may be the cause of that?

[besTint]

cant tell you what the problem is but i think all s13's can use a AIV clean. fairly easy to do, all you need is a screwdriver and a can of carb/choke cleaner. wouldnt hurt to do even if it aint the problem.

[crzycav86]

that's your tps going out or needs to be calibrated. use the fsm to figure out what voltage it should have at closed and wot throttle.