Oil pressure going to 0 when slowing down to pick up fallen rider

[culrich77]

So here's the problem I encountered last night at the lake. After a good hour of wakeboarding with no problems we started to surf. After about 30 minutes of surfing every time the rider would fall and I would slow down to turn around and the oil pressure would drop immediately and go super low, sometimes down to 0 and the alarm would go off, but as soon as I put it back into gear and gave it the throttle to turn around and pick the rider up it went back up and was normal. But then once the rider fell again the process would repeat itself??

I checked the oil before we launched, after this happened the first time and at the end of the night and it was spot on every time.

Anyone have any idea what could be causing this?

Thanks in advance!

[WakerideN]

what boat do you have ... meaning year and motor. could be your oil sending unit. Had a friend with a 05 supra that had this exact behavior. ended up being the wire on it that was not tight. but also later ended up having the motor have a cylinder go bad as well. I would have a compression test done.

[chuckhoenig]

Mine does that too, where is the oil sending unit on 2003 21i 350 MAG MPI?

Ill check it.

Thanks!

[culrich77]

I have a 2007 RZ2, the thing that is frustrating is that wakeboarding, waterskiing it's totally fine and nothing is wrong, only when surfing.

[Chads972150]

are you running more ballast when surfing? the reason i ask is it could be putting the boat at a different orintation such as bow up vs bow down and the motor rocking back and forth could in theory be causing in im not sure if these motors have what windage plates in them to help prevent that.

[culrich77]

Yeah 800 pounds on the surf side and 400 in the bow???

[chpthril]

Did you check the oil on the water with no ballast?

[culrich77]

Yes, we checked it when we emptied the regular side, drove around for like 5 minutes, then stopped and checked and it was right on. Do you think it's a bad sensor?

[chpthril]

No, heres why. A bad sender would be more random. 2, I believe your engine has 2 senders. one controls the gauge and the 2nd controls the buzzer. You are seeing an erratic gauge and getting a buzzer. The one thing they have in common, is the common tree that both connect to. If its getting restricted by a little sludge, both senders are effected.

[culrich77]

That makes sense, because the sensor is going to 0-10 and then if it hits 0 the alarm goes off, so should I change the oil and see if that helps?? It was changed last winter and I've only put 20 hours on the boat since unwinterizing it?

[chpthril]

what does the oil smell and feel like? Smell like oil or gas? fell slick/sticky or thin and solvent like?

[culrich77]

I didn't smell it but it felt and looked totally fine

[chpthril]

I would inspect to see of your engine has the double senders. If so, pull them out, remove the tree and flush it with brake clean to make sure its open. Also clean the port in the block and the opening of each sender. Then try. if its only got a single sender, then consider replacing.

[culrich77]

Great thanks for the info!!

[chuckhoenig]

Anyone know the location of the oil sending unit on the 350 mag MPI?