Fuel restriction alarm

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woodycooper

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Sep 6, 2022
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I'm getting a "no oil" alarm (beep every other second) from my VRO. I've tested according to the book by using a clear hose with 1/2" marks. When I run the motor at idle I see the oil level in the clear tube drop according to specs (3 inches in 6-8 pulses). I cannot hear or feel the "clicks" that the various instructions tell me I should, but I do see a 1/2" drop happen at regular intervals. Problem is, after running for about 2 minutes the alarm goes off. I know oil is being pumped because I can see it drop and I'm pretty sure the "clicks" correspond to each 1/2" drop.

So, what causes the "click"? The explanations I see show a small plunger sucking in oil with each cylinder cycle, and just pumps oil pretty much continuously. Is there a small reservoir that gets filled up and "pulses" when full? I'm more curious at how it all works really.

And finally, if oil is pumping, why the alarm? (no it's not an overheat alarm, or fuel restriction, or LOW oil). The fuel pump is brand new, although my luck at brand new parts has been atrocious. If the past is a guide then the brand new fuel pump has about a 50/50 chance of being the culprit. If so, how can I confirm this without re-loading the parts cannon again...

Thanks
 
Faztbullet

Faztbullet

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The click you hear is when the air motor check valve releases the diaphragm and diaphragm returns to position to start new cycle....disconnect onboard tank wiring to eliminate float sender
 
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saltchuckmatt

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Faztbullet said:
The click you hear is when the air motor check valve releases the diaphragm and diaphragm returns to position to start new cycle....disconnect onboard tank wiring to eliminate float sender
Click to expand...
The OP is still using the vro so I don't think he'd want to do that.
 
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woodycooper

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flyingscott said:
Why not? Do you know how a VRO tank works?
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To be clear, the alarm I get is not the low oil alarm. However I think you're saying that the two alarms are shorted together or somehow attached so that a bad sender causes no oil alarm? I can easily disconnect and try again. Right now the sender/pickup is removed from the tank but not disconnected.
 
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woodycooper

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Faztbullet said:
The click you hear is when the air motor check valve releases the diaphragm and diaphragm returns to position to start new cycle....disconnect onboard tank wiring to eliminate float sender
Click to expand...
Thanks but maybe I'm missing something... The air pulse/vacuum from the crank case makes one pulse/vacuum cycle each time that cylinder (5 or 6?) goes through two strokes, correct? From what I'm hearing it takes several revolutions of the crankshaft to fill the diaphragm before it releases via a check valve, and the vacuum events are prevented or dropped via the pulse limiter? When I replaced the pulse limiter I could blow through both ends and my understanding is that it just stops backfires from blowing out the pump.

Either way, the fuel and oil pumps fine, clicks or no clicks (or I can't hear or feel them) so I was really more curious to take a deep dive on how the whole pump setup functions. The alarm is my real issue and I'd really like to keep the VRO as pre-mixing is a pain.
 
flyingscott

flyingscott

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Those sensors in the pump can go bad. There is a replacement sensor but I don't remember the #
 
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woodycooper

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Faztbullet said:
If sender is removed from tank that's likely your issue
Click to expand...
The symptom has been there even when the tank was installed. I removed it to dispose of the old oil (and a bit of water). Once it warms up a little I'll disconnect the low oil sensor altogether and try the clear tube test again. Since these seemingly unrelated alarms could be tied together and I do resolve it by disconnecting that alarm, then what's the proposed fix? Bad sender in the oil tank? I'll look in my shop manual for a test procedure but I think while I'm at it I should test the Low Oil alarm simply by moving the float to the empty position. Will let you know later how this goes.
 
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woodycooper

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Post mortem:
In the process of fixing this, I now know more about Evinrude/Johnson fuel pumps than I have a right to. For everyone's edification and if someone has something to add since some of this stuff is black magic, then please feel free to respond.

This was a false positive alarm, due to a fault in the no oil circuitry. I discovered this by taking apart an old fuel pump and then observing the new one in action. The way the oil injection alarm works (as near as I can tell) is as follows:

There's a small chamber in the oil circuitry section. You can only see this by removing the four torx screws in the oil module (the farthest forward section). When the suction builds up enough, the chamber injects its contents into the fuel chamber. This is the "tick" that you may hear. When the oil gets injected a pin with a rubber seal in the forward half of the fuel chamber is pushed down into a switch on the oil module. That module takes engine RPM (or equivalent) and then compares that to how often the pin pushes the switch in, and resets each time. The pin only is pushed down when oil is injected. If there is no oil the pin doesn't press the switch and the alarm will go off. At idle it take a couple minutes. At higher RPM it happens almost immediately. Please note that the top two screws on the oil module also attach a small cover over the pin, switch, and contacts so you can only see what I'm talking about by removing it, but I have attached pictures.

In my case the button on the oil module wasn't connecting the two contacts to close the circuit. If the circuit isn't closed then after a certain time it will trigger the alarm. A few small screw drivers was all it took to bend the very tiny contacts so they would touch together each time the button is depressed by the pin.

Under the cover of the oil module. The pin and switch and contacts.
20221122_211908.jpg


20221122_211918.jpg

The pin sticking out of the front half of the fuel chamber. The pin fits in a hole that goes through the housing into the fuel chamber and it looks like air or fuel pushes out on the top half of the seal causing the pin to push down.

20221122_212035.jpg
 

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woodycooper

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dingbat said:

continuousWave: Whaler: Reference: VRO Fuel-Oil Mixing

OMC VRO fuel-oil mixing in outboard motors
continuouswave.com
Click to expand...
Thanks, I've seen this. It's about the best explanation I've seen of what happens "under the hood," however nothing I've read adequately explains how the no oil circuit actually works. I know that oil is injected each time the pin pushes the button down, but I had to figure that out myself. I guess it's like Microsoft Windows, nobody cares as long as it works, and if it doesn't they'll just say to replace it. If I can bend a contact with a screwdriver instead of paying 6-700 bucks for a new pump (which this was), then that's what I'll do, black magic or no.

Don't let me poo-poo your response though, it is appreciated.
 
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racerone

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There must be lots of VRO pumps with good warning / alarm circuits.-----Bins full of them at some shops.-----Make some phone calls and find one for cheap.
 
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