Warning Horn - SLOW oddities

[kjdunne]

89 40 hp Rude, electric start, remote control. Brief history, boat and motor fully winterized and garage stored for 1 1/2 years due to work travel and kitchen remodel project. In Aug. of this past season I rolled her out and woke her up. Drained and flushed fuel tank, new fuel, fuel filter, plugs, freshly charged battery, etc. Fired right up in driveway on muffs. Great so far. Changed plugs again after fogging oil burned out and headed to the boat launch. Engine fired right up and idled fine thru the 15 minute no wake zone to open water. When I opened the throttle, she ran up to about 3000 rpm for a few seconds and dropped back to no more than than 2000 rpm. It acted like it was starving for fuel, but pumping the fuel bulb did not help. I idled back to the launch with no problem, it ran fine under 1500 rpm. I rechecked the entire fuel system and took her out the next weekend and had the same problem. Thinking I had a fuel delivery problem, I replaced the VRO pump (ouch $$) to no avail. At this point, I realized I had not heard the warning horn test beep when I turned the key on. Testing the horn by connecting it directly to the battery proved it was shot, rusted beyond belief. I replaced it with a Radio Shack buzzer and then had constant horn on whenever the key was "on". Therefor the engine thought it was overheated and was in SLOW mode. I obtained an OEM manual and started troubleshooting. Temp switch checks OK, open to ground, with tan lead disconnected still constant horn. Tan lead to ignition module disconnected, constant horn. Tan lead fron VRO disconnected, constant horn. Grey lead from VRO, constant horn. Black lead from VRO discinnected, constant horn. Purple lead from VRO disconnected, constant horn. Oil tank sending unit disconnected, NO HORN! The oil tank connects to a tan wire that is tied to the tan VRO lead at the blocking diode and the tan wire that goes to the horn. I checked the oil sending unit lead, and it reads open to ground. I'm really perplexed at this point. The oil unit should cause a short beep every 20 seconds if the tank is less than 1/4 full. It is over !/2. Also, when the oil sending unit is disconnected, I still do not get the short test beep when I turn the key on.
Sorry to be so long winded, but I wanted to give as much info as possible.

 

[HighTrim]

Re: Warning Horn - SLOW oddities

Sounds as if your oil tank component is faulty. Also, is it a small black plastic horn that has a built in black ground wire? If so the tan wire must be attached to the terminal closest to that black wire. If not the oddities that you're encountering may happen.

 

[ob]

Re: Warning Horn - SLOW oddities

Be interesting to know whether the engine rpms in water will perform with the vro harness and oil reservoir leads disconnected.If not,your carburetors may be fouled.You could have tested that initially by repeatedly pushing the key primer when the engine wouldn't surpass 2000 rpm.

 

[seahorse5]

Re: Warning Horn - SLOW oddities

The oil pickup assembly contains an electronic circuit board in it (1995 and earlier) that generates the LOW OIL alarm at 30 second intervals, or so. When the electronics go flakey, they can make all kinds of wierd alarm sounds. You can leave it disconnected and visually check the oil level when you gas up, or spend the $90 or so for a new oil pickup, wiring, and hose assembly.

 

[kjdunne]

Re: Warning Horn - SLOW oddities

HighTrim, no built in ground wire on the horn I now have. Original did'nt have it either, just a sheet metal can type horn with a terminal for the tan and purple wires.

ob, I will be interested in water testing it with the wires disconnected, but that won't happen anytime soon here in NJ. If the oil tank sender is faulty, should I get a low resistance reading to ground? As best I can figure this out, the horn should sound when a connection to ground is made on the tan wire(s), ie: the temp. switch closing at high heat. By the way, overheating is definately not the problem, as I have the constant horn with the temp switch unplugged, and it was about 45F today when I was working on it, temp switch reads open to ground. Also, am I correct that the VRO pump will work with the wires disconnected, as it is driven by crankcase pulses, but the oil ratio may not be correct? I understand the possible carb issue, but the horn leads me to think SLOW (no pun intended, but maybe warranted).

A real head scratcher so far. Thanks for you help.

 

[ob]

Re: Warning Horn - SLOW oddities

Not sure what reading you would get by ohming the reservoir leads if faulty.I do know that by disconnecting the harness from the vro pump that it will not effect the ratio of its fuel/oil output.It is also common to experience a failure of the oil reservoir sender that initiates a constant alarm on that vintage engine.That in itself should not trigger the powerpack to go into s.l.o.w. mode.The s.lo.w. is initiated from the overheat sensor lead.This and the fact that the engine set out of use for 1 1/2 years is what sorta steers me in the direction of a resrticted carburetor/s issue along with the water test description you posted above.At this point I don't feel that the alarm issue and poor engine performance are related ,but instead are separate issues.Of course only further testing will verify.

 

[kjdunne]

Re: Warning Horn - SLOW oddities

To try to continue testing prior to "boating season" would a test wheel be of use? Excuse my ignorance, but does a test wheel need to be in a tank of water, or would it simulate an engine load on muffs?

 

[HighTrim]

Re: Warning Horn - SLOW oddities

Test wheels are special propellers used to run outboards in test tanks. Since the typical test tank provides very poor flow of water to the propeller, a engine run at high rpm’s in a test tank will often surge faster and slower as the propeller alternately “bites” the water and then loses it’s bite. This surging can make testing and adjusting an outboard difficult. Test wheels are designed to properly load the engine in test tank conditions but to produce no forward thrust, eliminating the surging. A test wheel can not be used to propel a boat, and is an object that you will probably never run across (minus a few of the guys on here ). You should be aware, however, that running your outboard in gear with it’s standard propeller in a 55 gal drum of water, for example, will cause this same surging and it is not necessarily indicative of a problem with the engine.

 

[seahorse5]

Re: Warning Horn - SLOW oddities

If the oil tank sender is faulty, should I get a low resistance reading to ground? As best I can figure this out, the horn should sound when a connection to ground is made on the tan wire(s), ie: the temp. switch closing at high heat. .

Reread my previous post about the electronics in the oil pickup.

There are logic circuits inside the pickup and you cannot test those components with an ohmmeter. You can remove the pickup and manually move the float up and down, and you will see where it makes contact to tell the logic chips to start a 30 second delay and then a beep to signal low oil in the tank.

 

[kjdunne]

Re: Warning Horn - SLOW oddities

Thanks, High Trim and Seahorse5. I'll keep posting as situation develops.

 

[rodbolt]

Re: Warning Horn - SLOW oddities

the original metal can style 2 wire horns havent been avalible for some years. the updated is a three wire horn.
the 2 wire horn does not self test and never did, the later 3 wire horn had the self test feature built into the horn but older boxs require modifications to install it.
instructions are included.
the later 2 wire plastic horn is for system check engines and will require the monitor,the tach or a horn driver to operate.
replacement of the VRO is reccomended at 6 year or so intravels.
as its a diaphram pulse style pump they do go bad, peridic replacement is always preferable to failure.
were it mine I would go ahead and rebuild the carbs, its simple and easy, replace the water pump and thermostat and most likly your issue would go away.
on the oil tank level sensor, thats your call.
it holds roughly 1.8 gallons, about enough for 100 gallons of gas at WOT.
simply fill the oil tank and each fuel fill and odds are high it wont ever get low.

 

[kjdunne]

Re: Warning Horn - SLOW oddities

Rodbolt- thanks for your input, the more minds the better. The carb rebuilds will be done as suggested by you and others. The oil tank is in a visable place, so low level is not a problem. I'm going to troubleshoot the oil level sending unit by simple draining/adding oil to see if there is a difference in the warning horn. If the sending unit is bad, is there any reason not to run with the sender disconnected, as long as I monitor tank level?