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L24 breaking up...cant tell whats going on


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I was going to post this on classic cars but apparently windows phone fails with forums...

 

Anyways, I just did he head gasket on my L24 about 2 months ago, put an N47 maxima head on it to replace the damaged E31, electric fuel pump and regulator (Maxima head is not cut for mechanical pump). Running verified 3psi out of the regulator. ZX E12-80 dizzy/module with stock rebuilt round top SUs. I spent the last few days getting the carbs dialed in. I'm very close to perfect tune but I can't drive it and dial it in because of the following issue.

 

Anytime I load the motor up, hills, hard driving, it starts to break up and will NOT rev. It feels like it starts running poor on every cylinder. I've reset the timing, checked float height, replaced needle and seat, set timing, etc. It has gotten more prominent then ever, happening on nearly every drive now. It makes it impossible to get anywhere.

 

the car idles fine when it starts to break up. After a few minutes idling its fine again for a short time until it starts breaking up again. I can usually clutch in and rev it a few times, and it will sort itself out for a short bit but its gotten useless now.

 

I can tell right before it starts to happen because it smells obviously rich and on decel it starts popping/backfiring from the exhaust. Timing is dead on 30degrees at full advance, and 10 at 800rpm.

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Cheap plug wires leaking/jumping/grounding out ? ( my 8mm wires don't do this :D ... I personally hate the new NGK cheapo wires ... the plugs are great though ! )

 

Stick a vacuum gauge on , and read the gauge itself to tell what the engine is trying to tell you ?

 

What do the spark plugs read ?

 

Are the carbs leaking at the throttle shafts ?

 

Sunk Float ? The float in my 390cfm sunk/stuck from sediment , and backfired/popped through deceleration. (certain cylinders will read richer as well.... as you know)

Perforated Float ? (not quite sunk , but not good either)

 

Have you verified that your e12-80 module is good ? (Nissan ones last , and aftermarkets do not usually... well anywhere near as long.... ) take it off , clean , apply grease , bolt back on or check via the xenon.com s130 fsm states.

Check your pickup in your distributor ?

Reluctor ?

Coil over-heated ? ( some coils just don't work as well lol)

Breaker-plate/vacuum advance all working smoothly ? ( I've had distributors that don't allow it to work at all.... cuz broken as fawk ... lol)

 

Just make sure your fuel pump is not a high-pressure one... some of those will over-come/over-power the regulators or carbs .... even with regulators to protect them.

I use the carter high volume lower pressure fuel pumps , and make sure I have a fuel return hooked up.

 

 

I've had a pertronix module ... in which the wires leading into the module .... one of them got chewed through vibration agaisnt the dizzy body ... cut the car out at a certain rpm , and cylinder. It was installed/protected correctly. Though it just happened. Looked at that  3-4 times before finally seeing it the 5th time.

 

 

 

Some of this is directly related ^^^ , and some of it is more or less related :D

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Gonna disregard that for a little bit, I'm on my phone so it hard to respond to all of that but I will get back to it ASAP when I'm in front of my computer

 

 

It started running poorly yesterday so I killed the engine immediatly and coasted to a safe place, pulled the float bowl covers, and found the front carb was EMPTY! I raised the float height a tad assuming the float was set lower then I thought, and it seemingly solved the issue, but caused the front carb to start flooding. No bueno. I lowered it a hair, it no longer floods, but now its acting up again. Weird thing is that this ONLY happens on the front carb, not the rear.

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Fuel filter was the first thing I thought. Needle and seat are both brand new.

 

 

It wasn't until I hooked up my fuel pressure gauge, that read a flat ZERO that i realized there was an issue.

 

Took a small clean bucket and disconnected the fuel pressure regulator 'output' and turned the pump on. It trickled... not even that...it was like a 2 year old spitting in a bucket. 

Did the same thing out of the pump, no different.

 

 

 

 

40 PSI through the fuel line and BAM sudden fuel pressure! Gonna drop and clean the tank out asap, and install a filter at the tank. 

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