1993 115hp: Can fast beep(machine gun) on non-vro motor

[rothfm]

I'm usually pretty good on this type of topic, but this is a bit odd.....

Lots of posts on this extremely fast beep from the horn...However I have no VRO, replaced to pulse port conventional pump last year and been running great. Very dependable motor, takes me to far way adventures!

Sunday, planning from Idle, the very fast beep started sort-of quiet and progressively got louder as I went faster...seemed to be based on RPM. If I idled back, it slowely dissappeared---again, progressively got quieter based on reduced RPM (same frequency). Repeated this 3 times before playing it safe, and idled in.

Once I had a wierd "scratchy" noise coming from the horn...and it was bad 12v contact on some of the main power lines....SO this issue, was wondering if somehow the Regulator, Tach or horn itself can show up as this very fast beep that seems to start as I plane and get louder, and reduce as I reduce rpm. 12v switched purple is tied to the Tach and horn too

Water flow out of heads is nice and heavy, Impeller is good/good indication. Head temps are normal and I tested Head temp switches-Have no indication of a heat issue.

 

[jakedaawg]

Check key switch and hatness for corrosion and voltage leak to other terminals. If good replace horn. Assuming vro was removed and all wires isolated properly.you should pay extra attention to tan, purple, grey and blk wires

 

[rothfm]

Thanks Jakedaawg...Cursory look today saw nothing electrically unusual. But I will be undoing all grounds and power, cleaning them up etc..

Appreciate it. Will post findings.

 

[jakedaawg]

Isolate and ohm eac wire. Boat side and connectors on engine to terminals.

 

[rothfm]

Hopefully testing in-water tonight.

I opened all connectors looking for issues. Cleaned all grounds and put in new star washers.

Took apart shifter to examine wires and horn all good.

Short tan wires, horn nice and solid sounding.

Barrel testing shows a cold start heating up the heads normally, stats opening and temps on one bank 134, the other about 139.

Wondering about 2 things, remembering that the issue happened several times going from idle up to planing speed:

1. Could i start to heat up when on plane & one of the head switches isnt making fully causing that sort of fast beep sound?

2. My rect/reg varys by rpm. Lows of 13.0 up to 15.5 at wot. Curious if i could have a semi-"unrectified" power output with an AC trace riding on my power lines causing that horn to fast beep??? Tach etc seems good. Could explain why its intensity follows RPM's.

Wish i had my old oscilloscope!

In dept water testing to come. If it will repeat i will drop each head switch after ensuring temps are Truely OK

Very strange as my harness has no VRO cable, i have No vro unit at all! So i dont think its a VRO type beep. Its very very fast

 

[rothfm]

Fixed? Posting reaulta if it can help someone.

Since i had no vro, cable or connectors, the fast beep couldnt have been from some phantom vro signal.

I found an arcing situation happening between the block and a coils ground. I cleaned all coil mounting posts, put in mew star washers.

Also opened all grounds, sanded clean, and all power connections

Test launch, ran it hard....,no more fast beep.