VRO2, question about "no oil flow" alarm

[WernerF]

Hi engine gurus,
1989 60hp J60TLCEA. I wanted to start the boating season and checked my engine on muffs. When I turn the key to ignition position, sometimes the normal short tone sounds, but sometimes a continuous quick pulse tone comes from the VRO. I disconnected the VRO plug to verify the VRO is causing the tone.
Immediately after I start the engine (after the normal tone), the "no oil" alarm sounds. Engine runs, smokes, and smells normally. After some seconds, (with the first pump stroke, I guess) the alarm stops.
I stop the engine, wait just a second, start again. Again, the "no oil" alarm sounds for the first (maybe 5) seconds.
Of course, the solution is to switch to premix. I just want to understand: Even if there was no oil flow, the VRO circuit would need to wait a certain time (depending on the rpm) for a pump stroke to come, before an alarm would be sent, right?

 

[SparkieBoat]

Re: VRO2, question about "no oil flow" alarm

I am not sure, if it is making an alarm at all ..I would be alarmed. it is a sign something is wrong. But I have never tried to trouble shoot a VRO, I just plugem and premix.

 

[boobie]

Re: VRO2, question about "no oil flow" alarm

Try disconnecting the wires that go to the oil tank once and see what happenes.

 

[WernerF]

Re: VRO2, question about "no oil flow" alarm

Thanks for your replies.
Yes, oil tank was a good idea, I forgot about it. Unfortunately it's not the culprit. Nothing changed with the oil tank disconnected from the tan wire.
Anyway, a VRO sending an alarm without tach pulses is bad. I thought one more day about it: The only electronics that was feasible in 1989 to fit into the limited space is a CMOS counter counting up tach pulses and being reset to zero by the pump stroke pulse. One of the counter taps also outputs the ca. 1Hz signal needed for the tone. I guess, the ignition-on reset (probably an RC-circuit) is defect, leaving a random counter value when the ignition is turned on. If this value is low, everything is fine. If it's higher than the alarm threshold, the tone sounds immediately. A mid value makes the alarm tone come too soon. In any case, after the first pump stroke the counter is reset and everything will work then. I can see all three scenarios on my VRO.
So now for me too it's time to

plugem and premix

.
PS: Funny somehow, but the only electronic circuit in my engine which haven't failed yet is the unreliable oil tank level sensor.

 

[Fed]

Re: VRO2, question about "no oil flow" alarm

You could put some oil in your tank to make it premix then still continue to sort out the vro at the same time.
After doing that I'd prime the vro as per the OMC manual then give it a run allowing a minute or two for the alarm to cut out.

 

[Chris1956]

Re: VRO2, question about "no oil flow" alarm

I did not think the 1989 models had the no oil alarms. You have a 4 wire OMS pump?

 

[WernerF]

Re: VRO2, question about "no oil flow" alarm

My engine has the 3 wire VRO2 pump (alcohol resistant, outlet fitting brown). I took the pump out today to take a look at the electronic circuit through the silicone potting compound. Among some chicken food parts there is a HEF4020 CMOS counter inside! Unfortunately the circuit is built on a ceramic substrate and not on a standard glass-epoxy PCB. These ceramic substrates cannot be soldered and often get micro-cracks over time due to temperature cycles. So there's no chance to make a repair.

 

[boobie]

Re: VRO2, question about "no oil flow" alarm

Another reason BRP only sells repair kits for the fuel side of the vro, not the oil side.

 

[WernerF]

Re: VRO2, question about "no oil flow" alarm

New insights about the VRO alarm circuit: I did not make it to give up. So I carefully scratched off the potting compound and depicted the circuit's schematic diagram.



Indeed, essentially the circuit is a counter, counting the tach pulses and triggering an alarm when the counter reaches 8192 (2 to the power of 13). So at 1000 rpm (= 100Hz tach frequency) it takes 82 seconds after the last successful oil pump stroke for the alarm to come. At 5500 rpm the circuit waits 15 seconds for a pump stroke.
The actual problem was the interaction between VRO and warning horn. The 3-wire VRO has no dedicated voltage supply wire, but is supplied through the tan wire via the warning horn. (This is the reason why the VRO always generates quick pulse tones, otherwise it would cut its own supply). Well I had replaced the warning horn with an OEM part before, but I did not realize it could have something to do with the spurious alarms. In the past seasons, with the old warning horn, occasionally the alarm sounded when I switched on the ignition, but when I switched off and on once more, the alarm did not come again, so it didn't bother me. But with the new warning horn, the alarm came almost every time.
For the counter starting at zero it is crucial that the supply voltage on the tan wire rises fast enough to perform the reset (C6 holds it's voltage low for a while). The new warning horn makes the voltage on the tan wire rise a little slower, so the counter reset failed.
My solution was to add a 1?F capacitor to C6 in order to make the circuit more immune to slow voltage rise. No wrong alarms anymore, and still the circuit counts the tach pulses and sends an alarm when it should do, at least it does so on my work bench.
I don't know what kind of potting compound OMC used, I filled up the circuit with silicone glue (Wacker Elastosil E41).

 

[stylesabu]

Re: VRO2, question about "no oil flow" alarm

my vro went out a year ago,its a 2000 model year and my alarms worked.they.re nice when they work. I now always run oil in my gas with vro hooked up,yea i use twice the oil i need but worse its going to do is foul plugs. i have only put 20 hours on it since replacing pump. once i trust it i may back off pre=mix,but never go out with out enough oil to add to tank if vro goes out again.

 

[cdn-pk]

Re: VRO2, question about "no oil flow" alarm

Awesome work Werner, nice to see the added troubleshooting of the VRO instead of just disconnecting it.

Thanks again

 

[SparkieBoat]

Re: VRO2, question about "no oil flow" alarm

just disconnect the stupid thing...premix rules...

 

[boobie]

Re: VRO2, question about "no oil flow" alarm

Agree X 2.

 

[mistertwister87]

Re: VRO2, question about "no oil flow" alarm

Wow. Here is a gentleman who knows what he is talking about!


Hats off to you, Sir.