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NA&CH

Stalling issue(under throttle)

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Hello Z family,

***Disclaimer I am completely new to the older Z world. I have an 03, 08  nismo now the papa 240z. ***

I purchased the Z feom BaT. Car started and drove perfectly. Under throttle and idle. It had a straight 3" exhaust and I could not take the "noise". I swapped the headers and exhaust for the Zstory system. Header through to the twin muffler. I took the car out for a drive and giving it throttle it starts to cut out around 5k and then shuts down. I restart and the same thing. 

 

When I first got the car home I was driving around town 30+ miles. Car shows Breakfast cruising. Loud cruises. But no issues at all. Cars fuel level would be above 1/2 tank at the minimum. 

Tank level now is at 1/8 full. I am going to assume I have sucked something in the lines but unsure. Take looks clean outside. No rot or major rust. I am going to drain the 1/8 in the tank clean the filter and clean out(change the easy lines the ones I can see). 

The Z has an electric fuel pump installed. Zstory header and exhaust. Su round tops with k&n filters. 

Could the su need rejet? Clean out? Am I thinking right with the fuel system? And is there anything I should be looking for or at whole under the car?

 

Thanks everyone in advance for any help that would get me enjoying the Z. 

 

Chris 

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Please ignore my Uv system... just found out that is broken as well. Any AC techs with advice there would be great 🙂

Chris

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That filter looks NASTY! I would agree with your suspicion that there is junk in the tank.

As far as the AC goes, am I missing something here? I didn't see a compressor or AC lines in your video.

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Funny, I saw the AC comment and completely missed the first post.  Didn't click.

To add to and follow SteveJ's comment, replace those filters.  With just one.  Each filter adds a pressure drop, even when clean.  Pretty sure I see three in serial.  That's a lot of work for the fuel pump.

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Replace that fuel filter, and at the barb of where the hose from
The fuel rail goes into the float bowl, there’s a filter located inside the barb, I would take those out and make sure they are clean as well if the issue persists after that filter change.


Sent from my iPhone using Classic Zcar Club mobile

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people forget about those filters and they get nasty over 40 plus years. 😊

It's the one that goes over the bolt, "internal gas filter" below.  I took mine out when I rebuilt the carbs.  I installed one of those glass filters right before the mechanical pump.  It stays nice and full now that I have the floats adjusted correctly.

Image result for 240z banjo bolt classiczcars.com

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Replaced the filter tonight. Drained some gas and the tank looks ro be clean. It does has some particles. Sand like. The old filter was FULL of soot doing its job. I purchased a new fuel pump as well. Plan on changing that if nothing changes with this simple fix. 

I have never messed with carbs but tonight I dis remove the filter and find some velocity stacks in there. I am going to clean the K&N filters. 

Would changing the exhaust cause the car to lean out or become to rich and cause this sputter?

Some pictures attached. 

Thank you all again for your help. 

Chris 

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I assumed that these things were in line with the filter in my other post.  Maybe not.  What the heck are they?

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On 7/11/2018 at 6:26 PM, NA&CH said:

took the car out for a drive and giving it throttle it starts to cut out around 5k and then shuts down. I restart and the same thing. 

What does your tachometer do when it "stall"s at high RPM?  Does it drop like a rock even though you're in gear?  Might be an ignition problem.  You have one of the early electronic ignition systems.

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It sure does drop like a rock. And jumps to full redline and then back to idle. It does it at higher rpm. 5k and above them it shuts off. Then I press the clutch in and it goes back to rpm.

That first pic is the fuel pumps correct? I believe it is the one off zcardepot. I just bought the one autozone has on their shelf. 53$ 

What would be a better ignition setup? I'll look through some items. 

Thank you for your help 

Chris

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If you're still in gear with the car rolling and the clutch engaged (wheels turning the engine), and the tach doesn't match engine speed that's a sign of no spark.  The tach is just a spark counter.

I was posting in another thread recently about the Fireball system.  If you have the optical trigger under your distributor cap in place of points then some trickery will be necessary if you want to keep avoid getting a new distributor.  Or you can just get a 280ZX distributor.  Or a 123 ignition system.  Many options.

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I just did a search and found you explaining the 123ignition. Pretty neat system. Looking into that now. I'll look through that thread as well. 

Thank you sir. 

Chris 

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Starting tinkering. 

Pulled the wires from the plugs and 2&3 have no change when pulled. All other drop idle significantly. Pulled all 1 at a time. Switch wire locations? I am matching up wires from cap. ?

I plan to replace the fireball system with something newer and current then maybe the 123 after I figure this out. 

Thanks again,

Chris

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I'm most likely totally off base here but #1,2 and 3 runoff the front carb.  May be a fuel problem.  I would pull those plugs one at a time a check their spark.  Good luck. 

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Spark plug Pictures from this past weekend. I have some tools arriving this week to do test on various items. Also something I should have done before jumping to the modification pages... the plugs are less then 2 months old. 

Any more insight is greatly appreciated. 

Chris 

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Using the Uni-syn and the front carb has little to no air pulling when at 2k. The rear is working. It is rich but working. What would cause the front carb to not be "working" or is this normal. Also where should the distributor be set at advance wise? 

Reading how to tune Su carbs now...

Chris

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 Sounds like the carbs are out of balance. Any early Z shop manual will tell you how to balance them. It's not difficult. I'd start with resetting the nozzles 2 1/2 turns down and then going thru the balance procedure. Dist. is usually set at around 10 degrees advance. There is a good thread about SU tuning. Google "Quick and dirty SU tuning.

Edited by Mark Maras

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Read the chapter in the FSM about the carbs.  Or just Google SU's.  They're not "normal", they use intake vacuum to raise a piston which then allows air flow.  What you see on the gauge is the vacuum on one side of the carb.  A higher number actually means less flow.  You might have a stuck piston.  They also use oil to damp the movement of the piston.  They're odd mechanisms!

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I believe you will need to get a front mounted airflow measurement tool, measuring from where you are is after the balance tube.

But I could be wrong, I would want someone else to double triple confirm.

Was there a filter in the engine compartment? There are two additional filters at the float chamber of the SU carb, for me it was throwing off my float measurements, and causing my stalling issues, after cleaning them out, I was able to get a good tune.


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Agree with what's been said above. 

A simple test would be to raise both pistons and see if they fall at the same rate, pretty slow fall if the damper oil is right.  They should make their "clunk" sound at the same time when they hit the bottom.

You need one of these if you have dual carbs, makes things so much easier. 

https://www.amazon.com/Latest-Rage-Deluxe-Carburetor-Airflow/dp/B00CMC57R0/ref=sr_1_fkmr0_4?ie=UTF8&qid=1532074358&sr=8-4-fkmr0&keywords=unisyn+carb

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Cleaned the front carb. Saw some markings. Any idea what they mean or are for. Also the piston pin with oil seams to be causing the piston to drag? Without the pin in the piston is free moving. With it installed it is tough to push up and it slides down... my gas gasket is broken and need a new one. Loss fuel in start up... Gas is also dripping from velocity stack just sitting. 

I turned the jet adjustment all the way lean when it was out. Righty tighty. 

Also should getting the float out be a royal PITA and me being afraid of breaking it?

Next rear carb cleaning. But I need a gasket to see if what I did was good. 

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