I recently bought a used boat powered by an Evinrude XP 150. First time out I babied it and ran it between 3500-4000 RPMs. No issues. Second time out I ran it around 4500-4800 RPM..the warning horn started beeping on and off in rapid succession. It is my understanding that is for low oil. I noticed the primer bulb was not getting super hard when primed. I also had asked the person I purchased from if he had replaced the fuel lines and bulb since we all love our ethanol gas....he hadn't. I went ahead and had the fuel lines and bulb replaced. New bulb is getting and staying hard. Compression also good for a 27 year old motor..all 6 within 4 pounds. Now let's forward to my third trip. Ran the engine at 3500-4000 on the first run...no horn. Decided to "test" it to see if the primer bulb and fuel line fixed the warning horn...proceeded to run it 5000-5200(5200 was WOT)....fine for a few minutes then the horn came on. Shut it down and proceeded to fish for a couple of hours. Then I took the last hour of my fishing day and tested the engine. I ran it at 3500-4000 for about 25 minutes straight without incident. Then I stepped it up to 4500-4800...after a few minutes the horn came on. I immediately took it down to idle speed...horn went off...stepped back up to 3500-4000 for a few minutes and no horn...stepped it up to 4800 and horn came back...back to idle..ok...back up to 3500-4000 for the rest of the day and no issues.

Any input is appreciated.

Tight Lines,
Mark

You need to have someone with you and when it comes on you need to squeeze the primer bulb for the oil and see if it goes away. If it does then the vro pump is bad or the pick up screen is stopped up.

What ever you do, add oil to the fuel until you know you have found the problem.

sounds like overheat to me, my 82 johnson did a rapid beep for overheat.

check the thermostats and popits and replace them, they are cheap.

if that engine is an 89 does it even have vro?

I can show you how to convert to electric fuel pump and you premix if it is vro or not, works much much better than the factory pumps.

Hop the VRO systems started in 1984 and some Johnsons after that were pre-mix motors called specials. I agree with converting to electric.