86 Johnson 150 dropping to idle while at full throttle

[Stumpy]

I've got a 86 Glastron with a 150 Johnson VRO V6 motor.

The problem I'm having is that while cruising at WOT it will suddenly all but die until I back the throttle off to idle. It will idle fine but as soon as I try to apply any throttle it tries to die again. Sometimes if I put it in neutral and free rev it it will rev up fine but as soon as I drop into drive it falls on its face again. Most of the time if I just let it idle in drive and just putt around it will eventually start working again, about 10-20 minutes. The compression is good, 100-105 across the board, new plugs, new fuel filter, fresh 92 octane fuel, etc.

Anyone have experience with this or any ideas what ay be the problem.

I don't get the VRO alarm when this happens but a few things I've seen on the web talk about the VRO possibly causing issues similar. I'm not opposed to disabling the VRO and premixing but if that's not the problem years of riding 2 stroke bikes and premixing makes the oil injection seem pretty nice.

Any suggestions would be greatly appreciated.

[marine_man]

Welcome to HSO!

What does the primer bulb look like when it does this? Is it full, or sucked flat? It somewhat sounds like a fuel pump problem to me.

Have you carbs been cleaned recently, or when you store it for extended periods of time do you run a fuel stabilizer through it?

marine_man

[Stumpy]

Thanks!

The primer bulb does not collapse or seem unusually soft when the problem occurs. I have replaced the bulb and fuel lines though just as a precaution.

I have ran sea foam spray thru the carbs and I run it very low on fuel when I store it for the winter as wel as some stabilizer.

[Sonicrunch]

You might as well scrap the VRO and go premix anyway. That unit is just too old to rely on for lubrication.

+1 on cleaning the carbs. Dang things can be so delicate.

[Stumpy]

Scrapping the VRO wouldn't bother me but I'm still not convinced that it's the problem.

I ran a couple tests to test the warning horn as I had not heard it ever sound. I was told that it make a short buzz when I first turn the key on the if I short the tan temp sensor wires at either head it should make a constant buzz. Neither of which happened. I pulled the throttle assembly apart to check the buzzer.

Found the warning buzzer problem, the buzzer itself was melted down!

I removed the buzzer and used my multimeter to check for voltage across the tan and purple wires that were connected to the buzzer. I got 12 volts when I shorted the temp sensor wires at the heads. Strangely the voltage didn't immediately drop when the short was removed. It instead slowly bled off.

Is there a capacitor in the warning system wiring that would cause this? Is this normal?

[boatfixer]

Do you have, or have access to a fuel pressure and vacuum tester?

[Stumpy]

I don't own one but I'm sure I can get my hands on one fairly easily.

Wat exactly would I be looking for?