nerdbebo

Morning,

I have a 1979 280zx N/A Auto. It's my weekend driver, or when my wife's Focus takes a crap or she whines and wants to take the 350z. (both happen quite often)

I've been noticing this problem over the last 3-4 months, I've ignored it cause its not a huge deal, but It's starting to bug me. I've done quite a bit of poking around on the net and I can't seem to find anyone else who has posted a similar problem.

Basically, while braking a bit harder than normal it dies completely, I can sometimes recover it by releasing the brake, and it'll fire back up on its own. I've tried switching to neutral, and then braking again, the same problem happens, It just goes from an idle to dead. It doesn't sputter and die slowly, the RPMs just drop dead.

Ideas? Thoughts?

NismoPick

Welcome to ZDriver!

Have you checked all the basics?

-CHTS (If equipped)
-AFM
-TPS
-O2 Sensor
-Timing
-Spark Plugs
-Cap & rotor
-Vacuum hoses
-All sensor & ecu connections (corrosion can impede performance)

nerdbebo

Yes, I've looked over everything that would typically cause problems. New dist cap and plugs, wires, I put in new vacuum hoses about 8-10 months ago. I checked the timing a couple weeks ago when i did the plugs.

Overall the car runs excellent, never dies or has issues, just this one area that baffles me.

NismoPick

Have you checked the fuel filter? Fuel pressure?

nerdbebo

The fuel filter is going on 2-3 years. How would I go about checking the fuel pressure?

NismoPick

The easiest way is to install the gauge right after the fuel filter. Pull the stock hose off the filter, connect the gauge hose... connect gauge... connect hose from gauge to fuel rail hose. Most major parts stores rent out tools & gauges, so you don't have to buy one.

But the problem only happens when you brake hard? How much gas is in the tank?

nerdbebo

Full tank of gas atm. ^^

It happens both when full and empty, Premium and Regular.

Should I check my fuel pressure? Like I mentioned before it runs great unless i'm braking hard, no hesitation at all.

KasbeKZ

i would start by double checking all the vacum lines attatched to the booster.

Ratfink

I second that. I think you are not running with enough vacuum. Meaning there could be a leak. There is less vacuum in the manifold when you hit the brakes. It is making up for the loss of vacuum in the brake booster when the pedal is depressed. if you are not pulling good vacuum to begin with, then there is not enough to pull the fuel from the carbs, and your car will die.
That could mean a vacuum leak anywhere in the system. Even at where the carbs are mounted. A way to find leaks if you cannot see them easy is to use carb cleaner, or wd-40. Spray all the gasket surfaces for the intake, and even around the vacuum lines. If you hear a change in idle when you hit an area, the that is where the leak it.


Good luck, keep us filed in.

tonsoffun300zx

im pretty sure it's efi so no carbs but same concept

Ratfink

Damn..... Didn't pay attention to what location I was at on the Forum... And, to get owned by TOF... hahaha
I think I just sprained my pride.

Yeah.. Could still be a vacuum leak. But, it is not because it is not pulling the gas out of the jets.

Good catch TOF.

nerdbebo

I'll give it a try this evening. Thanks for the tips.

WildmaN

Yeah that is quite possible. Good thinking guys, I don't know why I didn't think of that. Too much on my mind..lol