fuel pump?

[mac_daddy]

i was driving my 1990 240sx 5 spd yesterday and as i was taking my gf home i was in 3rd all the way on the gas and my speed started dropping. i let off and gave it gas again and it stayed solid at 40 mph. any help?i need to solve this asapthanks

[Vegascorbin]

Not much to go on. I would start with the general Tune-up type stuff and be sure to change the fuel filter along the way. It may or may not fix your problem but it will eliminate a lot of potentel suspects.

[mac_daddy]

thanks for the response, i already changed the plugs, wires, cap,rotor, fuel filter and still nothing. its seems lk when i go full throttle it doesnt wanna speed up but if i go about 1/2 way it picks up a lil bit. could it be tps? from 1000 rpm to about 2500 it pulls fine but it stops at about 4000 and wont go any faster... 1/2 way on the gas it slowly accelerates sorry this writeup is so long

[driftneil]

MAF

[mac_daddy]

how do i check that just unplug it and run it? wouldnt my idle be off?

[driftneil]

If you unplug and it changes nothing, that your prob.

[mac_daddy]

well i unplugged it and ran it and it was ten times worse so my maf is still good. is there a way to check my tps?

[aznb_boy89]

yea you check it with a multi-meter or with nissan datascan if you happen to have it. im not sure about the KA but with the SR at closed throttle it should be at exactly .45 volts or close to that. i would check to see if its the same for the KA though..

[mac_daddy]

i dont have a multi meter but i fi unplug it and the idle changes then does that mean its still good? im just stumped on what my problem could be

[aznb_boy89]

no not necessarily.. it could jus be a little off and when you unplugged it it threw it wayy off but my TPS was messed up and i had a dead spot in it where it wouldnt read between like 1.00 volt to like 2.00 volts and didnt really know for like 6 months! so id go get a multi meter for like 15 bucks and check it.. you can even get them at walmart

[mac_daddy]

what did yours do when the tps was off? anything similar to my symptoms?

[aznb_boy89]

bad idle sometimes. unsmooth powerband. and it would load up on fuel sometimes and not let me build boost correctly..

[mac_daddy]

mine just wont let me go past 4000 rpm and it accelerates slowly and i mean sloooowwly haha. i tried adjusting my tps like how ive seen on threads but no change

[aznb_boy89]

you tried checking your timing and cleaning your MAFS too?..

[mac_daddy]

yea i did just did the timing actually 15 degrees btdc like the single can should be but my timing chains goin out so im wonering if i bent a valve??

[aznb_boy89]

hmm im not sure about that one... so your timing was off though?

[mac_daddy]

well i put a new dizzy in it. not new but another one and just retimed it and its all good now. but my chains gettin bad im thinkin of either takin it to a shop or tradin for a 92 dual cam. this guy mite trade me. his needs a new fuel rail....

[mac_daddy]

oh and thanks a bunch for the help man

[aznb_boy89]

a new dizzy? what is that lol? the SR20 timing chain tensioner works off of oil pressure if im not mistaken,so if the KA's the same way then your oil pressure might be a little low if its real loose.. just a thought but no problem man. glad everything worked out.

[mac_daddy]

dizzy as in distributor sorry about the lingo hahaalrite i might check that out hopefully its loose and i can tighten it up and get her goin again

[Muskulito240sx]

it sounds like MAF to me also, plus when u changed the fuel filter did you also change the fuel strainer?

[mac_daddy]

no i didnt change the strainer i pulled out the fuel pump assembly but didnt really wanna take anything apart. would it help if i sprayed the strainer with brake clean?

[aznb_boy89]

naw i dont know if you wanna spray it with brake cleaner since its goin back in your gas tank.. if your gonna clean your strainer then id jus take it off the pump and clean it by hand with water first then alcohol. that way you dont have a chance of any of that brake cleaner gettin in your fuel system.

[mac_daddy]

ok no brake clean lol ill try to clean it when it gets back from the shop they can't really seem to find the problem either (newbs) lol

[Muskulito240sx]

their like $18 at advance auto parts

[mac_daddy]

the strainer? thats $18 i dont have right now haha im hoping the shop can diagnose it and tell me wats wrong so i can fix it because i dont know what else it could be

[mac_daddy]

i took my car into the local shop and they said they still haven't quite figured it out but they told me it's misfiring. i recently changed the distributor and used a mitsubishi distributor instead of hitachi because there are 2 types. so could that have been my problem? sending computer wrong signals?

[Wc240]

that may couse a problem.Check your fuel pressure at idle and wot and check the vacuum signal to the FPR.in the FSM there is a procedure on how to check/adjust your tps, is that the one you used? also, make sure your dist. isnt maxed out all the way. if it is, its timed wrong and your ecu cant advance the timing enough at WOT and youll get what your describing

[mac_daddy]

how do i check my fuel pressure? and at wot it doesnt wanna go past 4000 rpm. also for the tps i saw on a forum to warm engine, shut off, disconect tps, start up and turn screw until its at 650 rpm then shut off plug in and start up and its idling at 750 now. idk if that's right. my timing is dead on. it's a single cam so 15 degrees.

[Wc240]

the one your talking about is to se the base idle. you turn the idle adjustment screw until the idle is 650, then plug tps in and the idle should be 700+/- 50.make sure your unplugging the right one, there are two plugs(you probably know that)fuel pressure, youll need a fuel pressure gauge, if you have a vac gauge you can check the signal to the FPR. 15 deg is perfect, but like i said, make sure your dist. isnt clocked all the way one way. i recently went thru this with my single.If you still think its the fuelpump, slam the gass and check the voltage at the pump.check/clear codes and see if it still does this right away or if it takes a while.it wont go past 4k in idle either correct?