Fuel Pressure?

[nissandr1ft]

I'm having problems with my mainly stock KA breaking up at High RPM's. I'm basically gonna do a basic tuneup to make sure the plugs, cap, and rotor are good. I doubt thats the problem so I wanted to check my fuel pressure, but the only pressure tester I have isnt an inline tester like shown in the FSM. If I just put a pressure tester on the feed line, and put the key in the ON position what should my readings be? I tried it earlier, and only showed 20lbs, where as with the inline tester the FSM shows 34lbs with vacuum, and 43lbs with no vacuum.

Steven

[BC240]

I think you answered your own question. 34 w/ vac 43 no vac. Could you define "breaking up" at high rpms? could be a dying fuel pump.

[nissandr1ft]

Well if you take it to about 5500+ WOT it will start popping, and quit accelerating. I figure either the coils trash, or the fuel pumps not up to par.

[tre]

see my fuel pump went out on me VERY randomly. never had anything like that happen. Just after one track day drove to get food. then came out car wouldn't start.

[drew935]

have you replaced the fuel filter lately?

[nissandr1ft]

Yeah the fuel filter is a 300zx one that I threw in a few monthes ago...blew threw it to make sure it wasnt clogged when I threw the motor in.

[nissandr1ft]

Im almost positive its the pump now that I look at the plugs. I checked the gaps to make sure they were all relativly close to .040, and the coloring shows lean/hot... I think.

http://i77.photobucket.com/albums/j43/nissandrift/SparkPlug002.jpg

[davirene]

Yeah the fuel filter is a 300zx one that I threw in a few monthes ago...blew threw it to make sure it wasnt clogged when I threw the motor in.

If the fuel filter was brand new then you shouldnt need to blow through it? Poor exhaust aka bad cat could cause it to start to loose power at higher RPMS because the engine cant push out the exhaust? Your gas tank is clean?? Even if you put a new filter you could still pull sludge from the tank and clog the filter again??

Try putting a hardline in place of the fuel filter and see if it still stumbles??
:)

[tre]

wow .040 is pretty big. .032/.030 is better for your ka lol

[nissandr1ft]

Not brand new, it was used on my last motor for a month or 2. Theres not a cat, nor any emmissions equipment on the car. Ill check the gas tank in a sec, but I didnt have any problems with the filters getting clogged with the last motor. The FSM said .039-.043in (1.0-1.1mm) for the spark plug gap. Ill close the gap, a bit and see what happens.

[BC240]

If your not getting enough fuel that narrows your options quite a bit. change your fuel filter to a new stock one but most likely its your pump. When I test drove my car to buy it I told the guy it felt really slow and he responded "Its not a race car, dont expect it to be fast".

After I bought It I changed the filter and it was still choking, Right before I was gonna change the fuel pump it died on me. After replacing it the car was fast as hell. Also make sure if you get a pump to get a new filter condom for it, they dont always include them.

[nissandr1ft]

Yeah after looking at the plug, Im leaning towards the pump myself. I wont be able to go grab another one till tommorrow.

[tre]

here's a tip. i learn a lot from B at the Nissan Dealership. Its cheaper to get a fuel pump from schucks because its teh same thing cept it doesn't say nissan on it lol. He recommends me where to get parts lol.

[BC240]

I think mines a carter and its loud as hell, I think Walboros are pretty loud to. If you want a nice quiet one buy OEM

[nissandr1ft]

Im gonna throw a freinds old pump in to try, since he just replaced his with a Walbro. Not to worried about noise...S14 mani->3" SR DP->3" test pipe->3" exhaust is not the quitest thing out there.

[tre]

LOL OEM is not always quite. mine whines like a bitch. if i didn't have exhaust i'd hear it all the time :P

[drew935]

How's the ignition coil? Have you checked the secondary to see if it is still in spec?

[koukimonster139]

ok i dont know why nobody has told you yet, but those plugs are done. fried. way too hot/lean. you need new plugs after you figure out why its so lean.

[BC240]

hah good point, I hope you didn't put those back in.

[nissandr1ft]

On that topic whats everyones opinions on plugs...my freind that works at Nissan swears by NGK iridiums, I know most turbo guys go copper, and factory was platinum. I realize with copper you have to replace them more often, but other than that will there be a downside? If I know Im getting the correct fuel pressure, and its still breaking up the coil was going to be replaced next month by a MSD blaster SS anyways.

[BC240]

Im single tip platinum right now but ive also heard good things regarding iridiums. Im gonna have to let someone else drop the science on you. Either way if your not boosted plugs wont make a huge difference.

[nissandr1ft]

I just talked to another freind whos sort of a local guru who told me tanish color plugs are fairly normal for an N/A car. He mentioned high EGT's due to cruising, and the the stock ECU running pretty lean.

[drew935]

may get an afr reading at wot. I replace my plugs once/yr with stock NGKs and they're just fine on my car. Have run seafoam yet? I do that once/yr as well. Last time I did it(Just recently), there was no smoke out of my exhaust. That's how clean my car is running. If there's a lot of carbon buildup, then you'll see smoke out the exhaust like the space shuttle. :keke:

[180sxsun]

may get an afr reading at wot. I replace my plugs once/yr with stock NGKs and they're just fine on my car. Have run seafoam yet? I do that once/yr as well. Last time I did it(Just recently), there was no smoke out of my exhaust. That's how clean my car is running. If there's a lot of carbon buildup, then you'll see smoke out the exhaust like the space shuttle. :keke:
where can i get that seafoam stuff and how do i use it? (ive never heard of it before nor used it)

[drew935]

/\ you get it from the store. Search it on here as it has been posted before. Run it through your brake booster vacuum line and have it sip it from the can and into your int. mani for short.

[nissandr1ft]

Yeah I seafoamed it when I threw in the motor, but I tryed another fuel pump. I checked the pressure the same way I did with the old pump, and it read 50psi. Worked like a dream and runs great, thanx for the info guys.

[drew935]

good deal :2f2f:

[BC240]

Awesome man, go rip it up

[9524tee]

Damn, I'm having the same exact issue... I guess I'll try doing that too.

[underconstruction]

Yeah the fuel filter is a 300zx one that I threw in a few monthes ago...blew threw it to make sure it wasnt clogged when I threw the motor in.

Do you know the model number of that fuel filter? did you have to modify anything to get it to fit?

[drew935]

Just ask for a 95 300Zx TT fuel filter. No mod to get it to fit. The clamp holds it in. Just squeeze it in, that's all.