Clickys350z

Hello,

Im having a problem with my Z. I have an aem 320lph pump installed. Everything was running perfect when i built the engine. A couple days ago my car started acting funny. It would start to lean out on the afr on light throttle. It only started to happen when i was about 1/4 tank of gas. I figured gauge must be wrong. Added gas and it fixed the problem.
Now its just constant. It bogs and wont even go into boost.
What i have noticed is the fuel pump is not receiving battery voltage after accelerating for a couple mins. Battery is 14.1 and pump is 12.8.
I checked my entire wiring and its fine. Even swapped over a relay. I cut the wire and installed another 16 gauge wire to see if it would fix the problem, nothing. Still reads about 13 volts.
I changed the wires in the sending unit and nothing.

It feels like my car is starving for fuel every time i try to drive it normally. When the pump is around 13 volts, its starts making a loud humming noise and my car starts sputtering bad.
I bought a new quantum 340lph pump and same problem.

Does anyone have any issues with their upgraded pumps?

Or know of any wiring issues on early 350z?

Its has 850cc injectors, rails, steel braided lines, aeromotive copy fuel regulator.

It was working perfectly for the past month. Now it happened and it doesnt want to go into boost without sputtering.

BluestreamDE

Sorry to hear u are having issues, You mentioned that the Z was working fine for a while before the bogging problem. The fuel pumps seem to be working fine, and u already checked most of the fail points.

I also failed to see if you recently had a tune or retune on the car, if your fuel injectors are faulty and were tested for flow, and if your fuel pressure regulator is still working properly with the correct fuel pressure. If I were you, I would look at those.

Clickys350z

Thank you for your reply.
No i have not had a pro tune since ive finished my build.
This is actually the first car i tuned myself.
I based my calculations on my afr and i made them rich. It was running fine the entire time. Its funny cause now my afr sensor suddenly doesnt work anymore.
I think its good to mention that everytime the fuel pump reads under 12.8 volts, the pump starts making a humming noise(pretty loud) and my car gets worse in sputtering. Went into live tuning and i can relieve all of the free revving sputtering if i lower the K value, but it runs ugly under load. Although my afr sensor is out, i can tell its running lean because it doesnt even smell like e85 anymore.
I tried changing all 6 coils, gapped the spark plugs and checks for cracks. Plenum and lower intake checked for cracks, looking to see if i didnt have a danger to manifold condition.
I checked all injectors inside and out for clogging.
I havent checked for flow, but all 6 being plugged simultaneously is kinda rare. Im doubtful although i know it can happen.
I know its stupid, but i dont have a fuel gauge lol i only manually checked the fuel pump for pressure at the fuel sending unit which is very strong. Hits 120psi then drops and holds at 80. I even changed the adjustment screw on my regulator to see if it made any difference at all.
I thought it was my tune so i changed the maf setting back to stock and the car still sputters the same. Im lost guys.

BluestreamDE

First I would replace that o2 sensor. Then I would bring it to a local speed shop to get it professionally checked out and tuned. Its hard to tune for the first time on your own man especially on a boosted car where misfires and mistakes are more costly, I tune my Z myself but I had a lot of help from a friend in the beginning. It honestly sounds like just a tuning issue. I wouldn't worry on the sound of the fuel pump, my AEM 320lph is a little loud but my exhaust drones it out. The stronger the fuel pump the more loud it operates if I'm not mistaken.

Clickys350z

Yea thats what im going to do.
I mean it was running perfect for about a month with absolutely no issues. Its weird because as soon as the pump gets loud, my car sput
sputters worse. Ive even disconnected the pump harness while it's running and reconnected it and if it happens to quite down then it free revs perfectly.
I work at a shop and i built the entire car myself Besides machine work of course.

By any chance, could you measure the voltage at your pump connector? If u have a de then it should be the black yellow wire at the end of the connector on the pump. On cold starts, its reads damn near battery voltage. After a couple minutes of driving, the voltage drops a lot. Im convinced it some issue with the pump. Possibly alternator output is not providing enough amperage, but i doubt it lol

aarrgghh

So it no longer goes away on a totally full tank? Otherwise, sounds like it could be a swirl jet/line issue where you're pumping all of the fuel to the other side of the saddle tank. The sound you're hearing could be the pump running air/fuel mixture. Check that you modified the fuel pump basket correctly and that line on the basket didn't come off.

Clickys350z

No it does not go away now even on a full tank.

The line as in the plastic hose that draws gas from the side of the tank? I have not modified that one or anything from the other side.

Or if ur talking where the pump is housed in, i just removed the pump and made sure the rubber seal on top of the fuel pump outlet is not torn or the strainer is not kinked.

I looked for a pressure gauge at autozone, oreillys, napa and local parts store. The only have the american gauges that read only 15psi <_< i was thinking about using the oil pressure gauge they have there lol anyone have any in santa ana ca?

Today i pumped 91 gas. Runs a little better. Semi boost before it sputters

aarrgghh

If you didn't mod the swirl jet you may want to check out section 6 of this: http://host.cj-motorsports.com/pdf/3...uel%20Pump.pdf

That said, sounds like it could be the tune. I had a similar issue, don't yet know if it's fully solved (too much snow), but at 1/4 tank and hard runs I'd trip the Haltech lean and or fuel pressure low safeties. We've added a bunch of heat protection for the fuel lines (above the standard with that kit) and reflective gold foil after another local member had similar issues and finally tracked it down to hot fuel causing short term vapour lock in the lines.

Clickys350z

Good read, i will definitely modify that swirl jet, Although i feel like it only pertains to idle fuel pressures, whereas mine is all over the place lol

Btw i already changed out the af sensor. Says im running lean at idle, 18-20. Free revs to redline jump to 13-15afr.
Im going to try to modify my tune to fit the new circumstances at around 11 WOT.
I too am beginning to think that it is my tune that is fudging poop up. But like i keep saying. It was running perfect for about a month. Afr right where i wanted them, this happens and my tune is all over the place now as if im just starting it for the first time.

Interesting note about hot fuel lines. I did notice that when the voltage drops at the pump and it hums loudly, my harness tends to heat up( both power and ground wires). Also keep in mind that i now have a thicker 16 gauge wire directed from the front relay box to the pump. Even the gas inside the tank starts getting hot. Not super intensive hot, but enough to where i know it shouldnt be like that.

phunk2

You are going to need a fuel pressure gauge to diagnose a potential fuel pump issue. If the fuel pressure in the system is where it is supposed to be, regardless of any possible problem the fuel pump might still have (noise, voltage, etc), if the fuel pressure is correct, then the fuel pump has nothing to do with the engine stuttering and you need to look at the tuning.

Clickys350z

You are absolutely correct. I have ordered a fuel pressure gauge since no auto parts have any.

However, i did retune my car myself and now im
able to get into boost up until 5500+ rpm it seems to sputter. Only happens when the engine has been driven for a while. As soon as it warms up the afr are perfect and i can fully boost 3rd gear. After a 45 minute drive, boost sputters. I decided to get 1 step colder copper plugs. Regardless if it works or not, its better than the mismatched gapped down plugs that i threw on there hahaha
Its funny cause before it orginally had fueling issues, it would full boost without a hiccup.

We'll see.

Conway_160

iTrader: (1)

So what your saying is you have crappy, non gapped plugs and your missing under boost? Starting to sound like your plugs are jacked and your blowing out your spark.

Clickys350z

Essentially yes and no.

My car was running perfectly fine with the gapped down plugs. Until i noticed the loud humming noise.

Update. Just did the swirl jet mod. Now car is idling lean af. My afr gauge is going a-wall from super lean to extremely rich. I just replaced the sensor dangit. Might try another sensor since i cant read the afr anymore. Might be because i did the logworks firmware update. Gonna try recalibration

Clickys350z

Update.
Recalibration works on the lc2 wideband.

Now if anyone does tuning, can someone look at my map real quick?

Its like i keep stressing, it was working beautifully. Idk why it decided to take a poop. I guess this is what some people mean when they say they hate 350z ecus?

I know the maf values are a little low on the 4+volts, thats because i was trying high fuel pressure. And i also have a map with higher numbers for lower fuel pressure. I tried all sorts of combinations, but the end result is usually the same. The sputtering at around 5500 rpm

Turbo starts boost at around 4k and full boost by 5800 or so. But it doesnt hit full boosy now. Only 14psi

Uhh idk how to upload a file. But if anyone is interested, lmk please!!

aarrgghh

Ditch the copper plugs and get the correct one step colder iridium plugs.

Clickys350z

Awwww but i totally just bought these :<

Im doubting its spark blowout though. Couple reasons
1) when i added a spring to my wastegate to make it 14psi, it had spark blowout. So thats why i gapped the plugs lower to accommodate. It ran excellent.

2) copper 1 step colder should have a stronger spark, plus pull heat from the combustion since it has a longer wire correct?

aarrgghh

I've been helping run dyno sessions for the club up here with 12 to 16 cars per year for the last five years. We bring Specality Z up to tune. Helped pull and throw away several sets of copper plugs. Our cars don't like them. We tell everyone to show up with new plugs of the recommended type, no exceptions. It takes too long to screw around during dyno time.

rcdash

iTrader: (18)

dirty fuel filter or return line? Need that fuel pressure gauge to dx.

Clickys350z

Alrighty, i will try new plugs then. Ngk Iridium 1 step colder? Stock gap?

Sebastian at specialty Z has been kind enough to email me back with help.

Yes i have ordered the fuel gauge. Which should be here today if not tomorrow.
I thought maybe the lines were dirty, so i opened them up and cranked it to watch how strong fuel was coming out. Looks good haha

aarrgghh

Seb can get you the right part #, or a set. Just take them out of the box and put them in, don't touch the gap.

What are you tuning on (I'm on Haltech)? If you can, consider a fuel pressure sensor so you can log and use it as a safety.

Based on everything you've said I'm starting to suspect you may have been lean or fouled the plugs over time and that's why it went. How are you listening for knock while tuning? Gregg & Seb typically use headphones to a mic (300zx) or an amp connected to the stock knock sensor on the 350, Seb has a plug in ecu harness to tap the signal.