yup. But why are they there for a 502mpi that doesn’t use the Tbolt system ?

The wires he's referring to are on the HP 500, not the 502 mag.

The shutter was probably your power steering bleeding itself out. Check the level to make sure its full, and do a few locak to lock turns and it should correct itself.

Finally stopped raining around here and was able to look over the boat.

Got my hands on a manual and see that the brown wire with white stripe is for the oil temp sender on the HP 500. Funny thing is, I didn't see a brown wire with white stripe. Thought I did, but it was an aged purple with white stripe. So I may need to run another wire to the dash in order to use the trim gauge.

Bad news is, the brand new trim sender doesn't seem to be registering. Putting the ohm meter across both wires, it reads open.

So it appears I have a wiring and sender issue at the moment..

Not sure why, but the engine temp sensor was reading less than 1 ohm resistance from the sender to the back of the gauge. Last time I tried this, it was about 180 ohms. Got a new sender on the way though.

It's not much progress, but I am learning more about my boat.

Got me a gremlin.

While trying to figure out the trim gauge issue, I removed the main wire harness connection to check/test wiring. Saw no corrosion on the pins, put some dielectric grease on the connector and plugged it back in and tightened the hose clamp to retain it.

Miraculously, my engine temp gauge started working after this. I prob should have left it alone, but my new one showed up in the mail and I installed it. Took the boat out and the temp gauge doesn't work again.

While taking the boat out today for the second time this season, I pushed it a bit harder. We were turning about 4000-4500 RPM and cruising in 1-2's. Came off a little wave and the engine stumbled. My friend thought I bumped the stick back, I did not. Tachometer started reading higher RPM(like 1k higher) and the GPS speedometer I was told went into full sweep mode like it just woke up, but failed to read speed after that. I do think the compass was still working though? After shutting the engine off and restarting, it works again.

I did replace the gauges on the boat, so it's a good chance it's something I did, but the engine has been replaced with a used one also. So there's a whole bunch of things that can be causing this problem.

My mystery alarm came back on again.

1. Both cylinder heads are really warm. (can keep hand on both for 8-10 seconds before becoming uncomfortable)

2. Top of headers/tail pipes are warm. (can keep hand on indefinitely) Starboard side does seem to be a tad warmer than the port side

3. Individual pipes of headers (lower section coming off heads) are warm, with the front (#1 and #2 cyls) being really warm.

4. Thermostat housing is cool to touch.

5. Intake manifold is warm to touch.

Removed the tan/blu stripe sender wire and alarm didn't shut off. So I don't think I'm overheating.

Removed the wires from the out drive gear lube reservoir and didn't stop the alarm. I don't think it's that.

Oil pressure normally reads 40 PSI. I got the engine with 25W40 in it and had 40 PSI while on the garden hose/muffs for testing purposes. Changed the oil to 20W50 and no difference in pressure I could tell. After floating/hanging out for a few hours we were coming back in and I made a quick WOT pass. Oil pressure was reading about 20-25 PSI at idle no wake speed. I read this is normal for pressure to drop this low at low RPM after getting hot. Is that normal?

The alarm did come on after mild 2500-3k RPM cruising too, with 40 PSI oil pressure. So I don't think it's the hot oil low pressure reading that trips it. I do have a new sender coming in the mail just to try.

I am still getting a light burning rubber smell in the engine hatch though. No signs of where it's coming from. All belts are new when I got the engine. Power steering was a bit loose. (1" of travel) so I tightened it up a bit. Seems to have helped, but still getting smell. Nothing is rubbing on the pulleys. All battery cables are cool, nothing electrical is warm. (not an electrical burning smell, definitely rubber)


I do have a water pressure gauge installed. I failed to observe readings while making the one WOT pass, but it does read about 3-4 PSI at 2500-3k RPM. (Bravo 1 with high water intake) It does have a long way to go in order to reach the gauge. Maybe 20' of tubing, so I don't know if any PSI drops because of how far the gauge is? And the thermostat housing is cool to touch, so I think it wouldn't be the impeller? (was supposed to have been replaced, and the plastic housing does look new). Plus I don't think you would ever be able to smell that if it was the case.

That leaves the engine coupler, but nothing is acting odd back there.

The engine does run good and pulls good from any RPM thus far.

Got me some wrinkles to iron out, but should be a very fun boat when it's all good.

Should be closer to 20 psi at that rpm. Don't think your overheating with being able to keep your hand on the motor/exhaust

Did you ever find the oil pressure switch?

Do think you have some bad connects and it could be from the motor connector.

Maybe I'm not T'd in at a good spot for the water pressure? I'm threaded into the thermostat housing above the thermostat. Is there a better location? Because I am only getting 3-4 PSI according to the gauge. Everything is new.

I have a new oil pressure switch coming in the mail prob tomorrow.

I think you are correct with the engine harness connector. I reinstalled the old engine temp sender and it's not working again. (It didn't work. I fiddled around with the engine wiring harness and got it to work, replaced it with a new sender that didn't work, then reinstalled the old one and it didn't work again)

Just on a hunch, I ran an additional 10 AWG ground wire from the ground block behind the gauges in the dash to the ground block on the transom. Figured this might help identify a bad ground.

1. Still have an erratic tachometer reading (new gauges)

2. No problem found with speedo acting strange and today was wavier than yesterday.

I had a thought today that I need to look into. I'm assuming the alarm is for the engine. There is another alarm on my boat.

Thank you for taking the time to reply

Many have placed it there and they work, mine is Tee'd in the block drain

The engine connector looks good but might just be where the wires connect to the pins inside

Where is this project at? There may be some local tech's who could help you out.

"I had a thought today that I need to look into. I'm assuming the alarm is for the engine. There is another alarm on my boat."
I had an intermittent alarm that was driving me crazy only to find that my depth gauge was alarming, it was in the process of taking a dump.