I'm used to 40lb fuel regulators, but they weren't hooked up to the intake vacuum. Doesn't the vacuum line adjust the pressure (less pressure at high vacuum, more at low vacuum)?

If I recall correctly, I have $165 in this. About half of that is shipping and handling.

DD I take it thats US$? either way its a good price landed and everything.



This pic is a Fixed rate regulator.
Rising rate have fuel inlet, fuel return and manifold Vac/Boost reference.
The vac/boost reference controls the amount of fuel that returns to the tank, low vacuum means less fuel returns to tank since it is required for the engine,with this giving higher pressure. Hi vacuum more fuel returns to the tank as it isnt required, with this giving lower pressure.
Skylines even vary the voltage supplied to the pump to control pressure but they still run a reg. Like I said, rising rates vary. 1:1, 4:1 etc

Hardcore ehh.

rising rate fuel pressure reg is meant to iron out flat spots, improve throttle rsponse and generally enrich mixture. I have one on a modded 3.0 efi V6 mitsubishi. its set at 40psi and meant to increase pressure under vacuum at 1.7: 1, as opposed to the stock 1:1

I really think that they are a waste of time if tuning is already good, and dont do enough if the problem with tuning or lean running is fairly serious. programmable ecu much better option.

dd, something for you to keep in mind. These manifolds have a reputation for cracking around the bottoms of the ports, partly due to the clamping force applied when clamping the exhaust manifold and the inlet manifolds. Check your inlet manifold for hairline cracks, any cracks obviously get worse when engine heats up. The solution is to run a small seam of TIG weld around the bottom of the inlet runners where the flanges mate to the head. Be sure to make the weld small otherwise it will get in the way when bolting both manifolds to the head.

Cheers,

Paul.

Quote:

i agree.

Thanks for the tip, I'll be looking for any cracks.

Here's the regulator. It has an inlet, outlet, and vacuum line. I think the fuel lines are 5/16s ! compared to stock 1200 1/4-inch fuel lines. It has a fuel return line.


A14E EGI fuel regulator

Here's a thought about the cracking issue. The original 1200 intake is mounted on top of the exhaust manifold, is small & light with lots of support. The EFI manifold you have has much more mass that extends further away from the head & mounting points. Most EFI 4cyl cars that I work on, have a bracket from the outside edge or underside of the intake manifold down to the engine block. If one wasn't supplied, I'd put one on to try to help avoid cracking. A small piece of angle iron should do the trick.
Hope this is a help.

Hi DD,

Your idea of using the 200SX (sylvia) harness should work. Cross reference the part numbers for the 200SX injectors with the A14E injectors and the fuel regulators. If they are different you may need to change the parts to match what the harness/ECU is expecting.

The fuel regulator is designed to maintain a constant pressure across the injector. As the manifold vacuum drops the presure in the regulated fuel pressure will increase to compensate.

It seems that the best manual for describing how the factory injection system works was in a Haynes manual for the 1978 810. The 200SX manual is also good.

If I remember correctly (it was ~15 years ago that I was messing around in my friends autosalvage yard...) the 1980 US spec 200SX was open loop, no oxygen sensor where the O2 sensor was added in '81. Might makes things simpler to not have to deal with the 02 sensor...

Good luck and let us know what happens!

Gary

Bones. LOL.

dd, the fuel pressure regulator you have should give you fuel pressures around 35 - 40 psi. The reg you have is not considered a rising rate regulator but does need the vacuum line to keep the fuel pressure up to the rail. The vacuum line just ensures the fuel pressure remains somewhat constant and the reg ensures that any extra fuel goes back to the tank.