VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

[Fisherman1010]

to all OMC VRO experts,
rebuild my 90hp crossflow, and today took her to the lake for some testing.
I am kind of lazy, so like to use the vro, let the vro figure out how much oil she needs.
but before going full in, did some testing on the system.
Mind you, this is a 4-wire vro pump, no diodes in the wiring harness, year engine 1991.
Mixing the gas, untill i am 100 % sure alarm system is working as she should.
This what i found:
1-low oil system works, setting a low level in the oil tank triggered the alarm to a beep per 30seconds.
2-checked the heat sensors in boiling water and they ground when getting near 100 degrees celsius

But....
3-no oil alarm is strange.
checking it on the hose, i disconnected the oil supply hose at the vro and got no reaction at idle rpms
I just pulled the oil hose off, and let it drip the oil out, no alarm....
I plugged it off to create a vacuum, no alarm....
So, my first reaction was the vro no oil sensor/rpm counter is broken.

But when on the lake at 4000 rpms, it suddenly went crazy, it actually worked? What the .... is this.
De-throtteling it to idle stopped the alarm completely.
I am mistified, is not this system to work at all rpms?
In this sistuation i can troll all day without oil, letting me cluless of an oil problem.

Can somebody explain this to me, preferable a omc mecanic who worked on the vro's?

Pls do not bash this thread with: get rid of the vro and mix. Thx in advance for any help clarifying this to me.
Vro "no oil alarm" starting at 3000 rpms and dies when at 1500 rpms - YouTube

 

[seahorse5]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Do you have the original pump on the motor or a replacement one?

What does the fuel outlet fitting look like and what color? Is it held in place with an oval metal bracket and 2 Torx screws or does it look glued in place?

 

[Fisherman1010]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Seahorse,
I presume it is the original pump. Bougth the motor with the boat 3 years ago.
It has the brown fuel outlet, so alcohol resistent version.
Pump is working as should, pumping oil just nicely using the clear tube method.
It is just the alarm working only at + 3000 rpms.
Today i go out for an other test.
Meanwhile what do you make of it?

 

[emdsapmgr]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

This comment may not help much, but I'll offer my experience: My VRO will do the same thing when the oil tank is just starting to get low on oil. The tank float is evidently sensitive to how level the boat is with the water. Evidently when it gets up on plane, the tank is not as level and sounds the horn at about 3000 rpm's. If I idle back to the dock it's fine. In my case, refilling the tank fixes the horn issue. You could try a test on the float in your tank. If your oil tank is full, and you know the VRO is mixing properly, you could temporarily disconnect the float wire to the tank and see if you still get a horn at 3500. If not, it's a float issue. You can get odd horns in the VRO system if you mix oil tanks from certain model years. I have the wrong year tank on my 1992 70 Johnson. When my oil tank gets low, it sounds a constant horn (like an overheat) instead of the periodic beep that it should. Fortunately, the horn still gives a correct warning, regardless of how it sounds.

 

[Fisherman1010]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Thanks emdsapmgr,
your comments are well appreciated, by many of us.
Thing is, the low oil tank sensor is workin as should. No problem there.
It is the NO oil at the vro pump that gives me doubts.
You think the LOW oil sensor can screw up the NO oil sensor? Next time i am out, i will disconnect the Oil Tank wiring.
But than...
Today when starting the engine, no alarm sounds, except for the LOW oil tank sensor beep every 30 seconds.
Than after getting on plane above 3000 rpms the NO oil will begin to beep. Every half second depending on rpms.
But this is new,..... today the alarm kept on beeping also on idle. It did not do that yesterday, so it is very random behaviour.
Shutting the engine down, and starting it up again, won't trigger the NO oil alarm immediately. It first has to reach 3000 rpms again to let it start beeping again.
I just want to know what i encounter is it vro behaviour or is it malfunctioning?

 

[Fisherman1010]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

An other interesting read about the electronic part of the vro pump is this:http://forums.iboats.com/johnson-ev...-question-about-no-oil-flow-alarm-538948.html

 

[WernerF]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Hi Fisherman,
I did not fully understand: Is your oil system set up properly and you expect the alarm not to come? Or is it the other way round, the oil hose is disconnected right now and you do want the alarm tone to come?

Your video did not show whether the tach is working at all rpms. Is it?

 

[emdsapmgr]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Any chance your oil line has some air in it? After overhaul, did you re-bleed the oil line system? Is the oil line white sight-glass (inside the cowling) filled with a dark liquid (oil)?

 

[Fisherman1010]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

sorry guys, for the late response.
to @ emdsapmgr and wernerf, i disconnected the oil line supply hose, to trigger the no oil alarm. I wanted it to come on. For test purposes.
I found it strange that the no oil alarm is triggered above 3000rpms, like it has a trashold to pass?
I find this not asuring, to say the least.

 

[seahorse5]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Testing for a NO OIL alarm on a late model pump (1998 and newer) requires the engine to be running on a 50:1 mixture and above 1500 rpm. It can take as long as 5 minutes for the alarm to sound as there is residual oil inside the pump and the chambers. There is a special circuit in these pumps to dampen out false alarms.

If you are testing the motor on a hose, then it could take even longer as there is very little fuel flow with no load on the motor.

 

[w2much]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Werner, That is some incredible vro knowledge and trouble shooting . Alarms have haunted me for a few years, cost me an engine then having it rebuilt it still sounded. Replaced my pump and all is good now. I don't what the heck you were talking about regarding your testing , but I was impressed.

 

[Fisherman1010]

Re: VRO "no oil" alarm starts at 3500 rpms, dies when closing the gas.

Yes Seahorse, like you said, it takes a while untill the oil is gone to trigger the no oil alarm.
But, and this really annoys me is, that today while running mix in the tank, but with a hooked on vro system, the "no oil alarm" goes off while doing 5000 rpms. Tested it right away, with a clear hose, and the vro does pump oil.
It also idles strange, it sometimes puffs blue smoke, the moment the vro pump oil into the mixing area!
I think the oil side of this vro is letting me down.
The vro still has good fuel pump though, so i take no chances with this new engine and go the mix routing from now on.
So Seahorse,
one last question, can the oil side of the vro detoriate, although the vro fuel side is ok?
I was thinking of something else: my engine puts out high voltage 15,5 while doing 3500 rpms. Can a bad regulator trigger no oil alarms, since the grey wire of the vro counts rpms, and the purple wire feeds the vro counting module inside?I don't have a faulty tacho, it reads accurate.