Zero oil pressure?? WTF!!

[kouki-gymkhana]

I finally got my Defi BF gauges installed the other day (oil pressure and boost). I'm very concerned because the gauge is reading Z-E-R-O oil pressure at idle despite having the recommended amount of oil in the tray. The pressure rises appropriately as engine revs increase so I don't think that it's the oil pump (I think the motor would have been toast by now if it had truly crapped out on me). What do you think could be causing this? The only thing I can think of is the Mobil 1 full synthetic oil I have in there is just too thin but aside from that, I'm at a loss.

Any ideas or anything that I should check? I've only gone about 150miles since I changed the oil 2 months ago.

[Joe]

what are your pressure numbers at 2000, 4000, and 6000.

if you dont know them offhand do NOT go out rev your engine and check. its POSSIBLE the gauge is correct and you would only be inviting disaster. i sure as hell dobut its the oil causing this. i would look at something mechanical.

[narfdanarf]

is it a mechanical gauge? your line could just be kinked somewhere maybe.

[kouki-gymkhana]

No, the gauge is electrical. I checked the FSM the other day and it was reading correctly as the engine revs increased. My tach still doesn't read properly so I'm afraid I can't decipher the exact RPM that correlates with the pressure readings.

What could be causing low oil pressure if the level is fine and the oil pump seems to increase the pressure appropriately as revs increase??

BTW, my FAL fans just crapped out on me tonight and the car friggin' boiled over a bit. Damn it....I should have just gone KA-T.

[240sxed]

could it be that the pressure sender is placed in the wrong spot? maybe where there is not suposed to be oil pressure. (similar to a gravity feed)

[Joe]

could it be that the pressure sender is placed in the wrong spot? maybe where there is not suposed to be oil pressure. (similar to a gravity feed)

then he wouldnt read pressure at allhe reads it just not at idle.

[Nowhere]

Take the gauge out of the pod/wherever it's mounted.Have a hot wire, ground DIRECTLY to the battery, an engine ground, and the sensor lead. Test the pressure on the side of the car (outside, have the gauge in your hand). Have the engine/sensor ground tied in with the battery ground, wire up the +12v and re take your measurements.

You're probably floating a ground and are getting inaccurate readings.

A failsafe, use/try a mechanical gauge..

[CursedGTR]

This may be a stupid question but here goes...... Did you set your control box for the engine you are using? There are switches on the side that have to be set. If they are not set right, your tach and other features will not work correctly. I always sat start at the beginning.

[kouki-gymkhana]

The control unit has dip switches to select the number of cylinders only on the port that accepts input for the tachometer. There is no required setting for oil pressure, temp, etc that I'm aware of. I'll see if I can get a hold of a mechanical gauge and see what the actual pressure is. The gauges are grounded correctly (I double checked the instruction manual and the wiring.)

The only other thing that I can think of is the fact that I'm not using an adaptor to fit the pressure sensor into the block. At first I thought I was going to have to buy an NPT to BSPT adaptor but when I actually went to install the sensor, it screwed right into the block and doesn't leak. Other than that, I'm still clueless.

[Nowhere]

If you're floating a ground, your readings will be incorrect.....

Electric oil pressure meters rely on resistance to give an output, if there's any difference on voltage/resistance between the gauge/sensor/electrical system, your measurements will be off..

EASIEST thing to do is use a mechanical gauge. Calibrate/diagnose/fix your electrical unit with a mechanical one..

['90_240sx_Lover]

If the sender is in the same line that is feeding the turbo, the turbo bleeds off so much oil at idle it wouldn't sense any pressure, it will also cause lower pressure at all times in that spot. You should put it in another oil port off the engine.

[GTR Shop]

Nissans RB engine have a nasty habbitvof having the screws come loose from the backing plate of the oil pump. VERY common and a common reason for run b/end bearings.