# 1994 nissan 4×4



## Chuck2346 (Apr 29, 2020)

I have a 1994 nissan 4×4 with a 4 cylinder in it.it is acting like it is running out of gas and it full


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## rogoman (Dec 16, 2004)

First of all, you did not specify what model Nissan vehicle you have. Is your problem occurring at idle or steady highway driving or during acceleration?

However in the interim I'll describe some general diagnostic procedures that you can try:

* You may have dirty spark plugs, dirty air filter, dirty fuel filter. Replace them if they're old.

* The fuel pressure may be incorrect. Tee-in a temporary fuel pressure gauge between the fuel feed hose and the fuel rail. The readings at idle should be as follows:

with vacuum hose connected to the fuel pressure regulator: 34 psi
with vacuum hose disconnected from the fuel pressure regulator: 43 psi
* There may be a major intake system vacuum leak. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be around 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.


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## Chuck2346 (Apr 29, 2020)

Thanks .it is a 1994 Nissan 4×4 it idel way to high and sputters going down road.i think its the mafs


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## rogoman (Dec 16, 2004)

Perform an ECU code readout to see what fault codes may be set. Before you condemn the MAF, perform the diagnostic procedures I outlined in my previous post. If it turns out to be a defective MAF, replace it with a re-man'd OEM MAF, not some aftermarket item. Aftermarket MAFs sometimes are unreliable, don't last long and many times are DOA!


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