1991 150 hp V6 Warning Beep - Varies with RPM

Hello all...trying to figure out what this motor is trying to tell me.
It's a 1991 V6 150HP (edit...titled as 1991, actually 1990 E150STLESB from what I can find), VRO has been removed, running pre-mix.

New controls with the Johnsonrude adapter to allow use on the older motor.

It's been running fine for a while now, but this weekend it started giving a "beee beee beee beee" after a few minutes of running. The beep varies with the motor speed. I checked and the brown (tan?) wire that I THINK is the VRO warning sensor is un-plugged. For testing I remvoed the wires that connect to the head in a potted epoxy spot near the top of each bank. I assume these are the temp sensors. No change. Then I noticed a "T" the main fuel line that runs to a sensor with some wiring. Guessing this is a fuel pressure sensor? I disconnected it and tested, again no change.

I'm lost trying to figure out what this warning is. I have found several posts concerning "normal warnings". Steady tone = overheat, beep every 1 (some say 2??) seconds = no oil; beep every 20 seconds = low oil. No luck on the "audio tachometer" (ha ha ha) beep.

Thanks for any input!

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

Well, you've disconnected all of the warning sensors apparently and the horn continues beeping. That would indicate that the horn has failed (if indeed you had all the sensors disconnected at the same time).

To double check the horn..... with the horn sounding off as you describe, remove the TAN wire from the horn. If the horn continues to beep, the horn is faulty and requires replacing.

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

I went to test as Joe suggested this evening. I started the motor and ran it for a while, no alarm. BUT.. the tach was acting very goofy. At startup (warm up lever up a bit, so it was above the 800 rpm ish idle) the tach read 0. After it was warm, I pullled the warm up lever back to idle, and the tach read about 800. Rev the motor, tach drops to 0. Saturday when I was getting the crazy alarm, the tach was working.

I'm in the process of checking all the grounds as a start. Then I'll check the connections at the big red plug. Might find electric goblins....I hope.

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

All the grounds have been cleaned shiny and show 0 ohms. I think I've eliminated a grounding problem.

After mining for posts on tachometers, I see that the tach signal is from the charging system. Based on that, I decided to check the battery voltage with the engine off (12.34vdc) and running about 2000 rpm (12.34vdc). It appears that the charging system is no longer functional. I wonder if, while it was on it's way out, it overcharged/undercharged enough to cause the strange horn signal?

Now to go mining for how to check the charging system. I see there are several variations (9 amp, 35 amp, watercooled....). My motor is a 1990 150 XP V6 model E150STLESB. Anyone know which system this has?

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

That engine has the 35 ampere stator and the water cooled voltage regulator/rectifier.

Look under the flywheel at the rear portion of the stator. THere are two large black coils there that are th beginning of the ignition system. Should either of those coils be melting down, dripping a sticky looking substance down on the powerhead, replace the stator.

Those two coils provide approximately 300v to the powerpack in order to energize the ignition. When they start to melt down, a voltage drop takes place resulting in weak, erratic, and eventually no ignition.

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Remove that gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

Hello i just wanted to chime in a little THe last time i had an alaram going off it sounded similar to what you explained it was a varied beep beeeep beeeeeeep wasnt just one of the noramal constant beep or even spaced apart it was just random and would change depending on how fast i was going and rough the water was . Turned out to be that the tan wire had a couple bare spots and when were grounding out causing the alarm to sound so im guessing that if you unplugged the sensors at the senders and it was still sounding you either have a tan wire grounding out or yur alarm may be on the way out but I strongly feel that its a ground .I suggest if you get the change to carefully check the tan wires . I had a bare spot close to where the tan wire goes into the big red plug with the diode . and the other spot i found was under my console onse i fixed them up the alarm worked great

on another note im having a similar issue with my tach usually when i first get in the water and im idling the tach seems fine but once the motor warms up some after about 5 min it eventually will just drop to zero and stay there the rest of the day let me know if you figure it out ive also been told that its possibly my regulator/rectifier and will be running the tests that were poseted for you i hope its not my regulater cause the cheapest ive found an oem is around 300 bucks
thanks

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

Ok, tested using Joe's suggestion. 1st I verified that the grey wire was the one that went to the tach connector (grey, purple and black) using a long test lead. The one that went to the tach was a pigtail with 2 grey wires coming from it, the other grey wire was a single wire that looks like it goes back to the R/R. I also verified that there is battery voltage present between the purple and the black wires in the tach connector. It looks like that purple wire is what feeds 12vdc top all of the guages and their lights too. Interesting.

Hooking the grey wire to the post with the yellow/grey wire and running the motor, I saw no difference in the way the tach acted. Still showing 800rpm at idle, dropping to 0 when the throttle is opened. I tried the solid yellow too, same results.

I also noticed that the bottom position on the terminal strip has only one wire connected. After shopping for R/Rs today and reading about the Mallory not using a purple wire, it makes me wonder if the R/R has been replaced with something of the sort?

End result of today's test is no difference in the way the tach acts, no charging AND now a constant horn unless the tan and purple wires are disconnected from the horn.

Made me go look at 4 cycle prices on iboats. Dream...dream...dream....

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

Pertaining to a three (3) wire warning horn.... built in black ground wire and two slide on terminals. The TAN wire must be connected to the slide on terminal closest to the black ground wire.... with the purple wire connected to the remaining terminal. Otherwise, weird horn happenings will take place.

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

I have high confidence that the horn / tach / ignition wiring is correct. I replaced the control box (all chewed up inside) with a new model OMC side mount control and used the OMC adapter (OMC #176711) to connect it all up. The horn wires were untouched 'till the other day when I started unplugging things to test it.

I'll check the condition of the yellow wires today, looking for shorts or breaks.

Re: 1991 150 hp V6 Warning Beep - Varies with RPM

You did not mention the sensor wire in the remote oil tank. You will get a horn from it (not usually of that specific sound sequence) when the oil is low, or the sensor is bad.