Mechanics

FUEL PRESSURE LOSS/ START PROBLEM

1994 Nissan Sentra

Engine Performance problem
1994 Nissan Sentra 4 cyl Front Wheel Drive Automatic 103500 miles

Hi,
I have a 1994 Nissan Sentra LE with a 1.6 GA16DE engine with 103,500 miles.
I began to have a starting problem some time ago, and found some bad injectors.
Recently, a new start problem began, and I found a leaking injector o-ring.

Now, checking fuel pressure, when I turn on the key, the needle goes up to 43 PSI, then instantly falls to 10 PSI and slowly bleeds off to 0.

I see no leaking o-rings or injectors now and the engine runs very well, but is still a bit difficult to start at times, having to hold the accelerator down.

I suspect the fuel pump, but is it possible the crank sensor is faulty, cutting the pump off?
Any other thoughts would be appreciated as well.

Thanks
Chris
Avatar
ChristopherEllington
July 24, 2010.



Hi ChristopherEllington,

Problem is the fuel pressure and not sensors. If it is sensor fault, the fuel pressure would remain at 43 psi and if any drop, would be minimal.

There is a leak in the pressure and if no external leakages are found, you would need to check the internal. As the fuel pump is working and vehicles runs, the pump itself is not faulty but rather the pressure regulator or the hose between the pump and fuel rail.

At the fuel pressure regulator. Pinch the return hose and retest if the pressure drops. If they do not dro, then pressure regulator is bad.

If pressure drops, remove the fuel pump and check the hose between the pump and housing for leakages.

KHLow2008
Jul 25, 2010.