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Intermittent running lean??, Ramble ramble. Mumble muble


stagefumer11

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Long story.. lets hope i type this right :P

 

4 weeks ago i noticed after going w.o.t in 2nd gear that my skyline cut out completly. It was quite a hard cut, The symptoms of no spark feeling.

Now any session of hard driving it will always stutter and fall flat on its ***. It didnt really come to this untill 2 weeks after the cut out happend.

 

Last week. All turned to sh!t. Any full thorrtle eccel will fall the motor into stalling or falling flat on its ***. looking at my A/f guage it was going MEGA Lean. Which lead me to think my fuel pump was stuffed. Note this pump installed is a Euro bosh unit rated to 600hp. (so i wasnt to happy).

 

I replaced the fuel pump. this is where i noticed something, The pickup feed from the tank when removoing the pump flowed nicely for about 10 seconds then slowly dribbled to a stop, I was thinking this was a "vacume" in the tank doing so. (maybe not ?) Installed my walbro440 unit.

 

Fired the motor over. It took over 5 mins of cranking to get anything. Then as a random switch going on, It fired up like normal. Drove it all around that night caning the *** off it. And no problems.

 

Next day....... Same problem was back. :( ""crys" Full throttle = stumbles, ect yada yada. Noting the A/f guage didnt have a lean spot in boost. But was dropping off guage. Same thing again ?. Checked my voltage at the fuel pump, 11.2 volts. Ok thats not right. Voltage at battery 11.2. Rev the motor 10.5. Load the who system up. 9.2v. Well you can see where this is going. My alternator is poked.

 

After replacing my alternator (only one year old brand new) and my fuel filter, just un case. I was getting a nice 13.8volts everywhere. Even loading it all up heavly. Thank god. Car ran great. Smooth torquey. couldnt complain; Apart from the slipping clutch. LOL.

 

Took the old girl to work. later in the day i droped something off at one of out trade guys garrage, the car was sitting idleing for around 5 mins, Hoped in drove off. And bam LEAN LEAN LEAN on wof. stumbles falls on it ***. you name it again. As you can see im getting pissed off. Unpluged and pluged back in the ecu. Still the same. Drove it 10k back to work. Still running like crap in boost. Turned the corner on the street at work. Nailed it. And bam. Back to Normal. NO lean. ?!?!?!?!!?!?!?!?!!?!?!?!

 

End of the day. driving home, Oh wait Lean was back again. :( after 15 mins of 100kmph driving, it came right.

 

I am confused...... Is that fuel pickup blocked. ? Im not really keen on droping the tank out. Anything else that can cause this random Leaning out issue ?. I havnt done anything diffrent on the vehical to make it do this. Timing ect. Just one day it went like a switch. For a few weeks it didnt show up leaning out problems, then showed the signs.

 

Eitherway, Help ? ideas ? Im completly flat broke for a week. so something of a cheep fix ;)

 

 

Edit, Btw. This is in a 85 HR30 Skyline coupe. L20et with rb20 turbo, FMIC. ect.....

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I suffer the same malady, suspect poor fuel which causes inj to clog, especially overnight during hot soak. This is more frequent now that we are in midst of another fuel crisis. There are now several gas stations I will no longer visit. Gas can be purchased cheaper on the spot market, but it may be quite old and prone to clogging inj. Don't buy cheapest fuel during a crisis, you may be getting old fuel that has been in storage longer.

 

Suggest either replacement of fuel or just take long trip to burn it out. Driving at freeway speeds for extended periods (50-75 mi) may clear it up. Try a can of Techeron.

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I had problems with my z recently where it would run lean, then rich as hell but most of the time rich. And it was due to a faulty fuel pressure regulator. Check that out or replace it, because if thats faulty it wont be restricting the fuel to get you the right pressure.

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