"Low Oil Alarm"

Hi all, I know this has been discused before. We just got a boat with
a 1991 Johnson, 40 Hp motor with the VR02 system. The boat has never
seen salt water.

It has a continuous alarm when the key is turned on and the motor
running. Motor runs fine and is not overheating or starving for fuel.
Lots of smoke, so it looks like it is getting oil.

This should be a non-oil related alarm, but when I break the tan wire
coming from the oil tank, alarm goes away. The buzzer was replaced
with a new one, and same prob.

I removed the tank pickup and removed all the green "potting compound"
to expose a small circuit board inside. There is an IC with the part
number: MC14467. This is listed as Ionization Smoke Detector IC.

There is also a small SS washer which appears to short out some
contacts and the alarm somehow comes on. Although the alarm is always
on regardless of contact or not.

It seems that a better oil tank level system should have been designed
with a low voltage float system like the fuel gage in a "typical" car.
No circuit required at the tank. Just a simple resistance test to
determined if sender faulty. I guess cost was an issue


I put a pot between the 2 removed contacts at the engine side and
simulated the various alarms:

Pot-Resistance Alarm/beeps

less than 250 Ohm Continuous beep
around 250 Ohm Rapid short beeps
above 2K Ohm No beeping

So, my question is:

Is it normal for the oil tank sender to fail?

How is the oil tank sender supposed to work? How does it distinguish a
low oil level from an emtpy tank?

Am I maybe looking at the wrong sender which is causing the alarm?

Jason

"JasonW" <jlwas.DeleteThis@hotmail.com> wrote in message
news:924147be.0405151952.5b26e00f@posting.google.com...
 > Hi all, I know this has been discused before. We just got a boat with
 > a 1991 Johnson, 40 Hp motor with the VR02 system.
 >
 > It has a continuous alarm when the key is turned on and the motor
 > running. Motor runs fine and is not overheating or starving for fuel.
 > Lots of smoke, so it looks like it is getting oil.
 >
 > This should be a non-oil related alarm, but when I break the tan wire
 > coming from the oil tank, alarm goes away. The buzzer was replaced
 > with a new one, and same prob.
 >
 >

 > It seems that a better oil tank level system should have been designed
 > with a low voltage float system like the fuel gage in a "typical" car.
 > No circuit required at the tank. Just a simple resistance test to
 > determined if sender faulty. I guess cost was an issue
 >
 >
 > Is it normal for the oil tank sender to fail?
 >
 > How is the oil tank sender supposed to work? How does it distinguish a
 > low oil level from an emtpy tank?
 >
 >


In 1996 for the System Check 4-lite indicator warning system, the float in
the tank "shorts" against contacts and that signals the LOW OIL lite to come
on and the horn sound for 10 seconds. Prior to '96, the low oil system used
electronics inside the pickup assembly to generate a single horn beep every
20-40 seconds to alert the operator of less than 2 quarts of oil remained.
If the motor ran out of oil, then the oil pump alarm circuit would sense a
lack of pressure inside the pump piston and sound a on-and-off beeping
sound. Sometimes the electronics inside the older tank units would get
flakey and give off all kinds of weird signals ranging from a "warble" to a
steady buzz. The factory also makes an optional oil level sender and dash
mounted gauge that operates just like a fuel level indicator, that you can
install in your tank. Since a new electronic pickup assembly is about $75 or
so, most folks just make a point to check the oil every time they fill up
and disconnect the tank wiring.

Bill Grannis
service manager<!-- ~MESSAGE_AFTER~ -->