Erratic oil pressure find
 

I have been having erratic oil pressure readings for a long time now. Typically, it would happen only when I would increase throttle or run at high rpm. Pressure would always return to normal when rpms came back down. I had tightened the crimp on the sender and that cleared it up only to have it return. Well, I just changed out ignition wires and the problem went away. My only guess is that the one that had a leak (was arcing) was the one that runs right by the lead to the oil pressure sender. It must have been disturbing the signal from the sender. I may or may not be the only one to see this happen. BTW the engine is a '96 502 mag mpi.

Rene

I beleave a arcing wire could give erratic readings on a
electric sender.

I had my share of electric senders. I switched to all
mehcanical with the exception of the fuel pressure.

Gerry

The senders fail and sometimes cause erratic readings. They are cheap and might be worth a shot.

I pulled a motor over a stupid electric oil gage and sender. Always check those first!

I had the same issue last month. I pulled the oil filter, cut it open, and found the element collapsed in several places. I changed the oil and the filter and everything was back to normal again.

Windage in the oil pan will cause just that at WOT. The crank areates the oil and the pump sucks air intermittantly. Try lowering the oil level by one quart. I ended up putting on new pans but the lower oil level did helped in the mean time. Then though you need to watch the oil temp closely because the oil is turning more quickly throught the engine.

BT :cool:

not to tell ya what to due but the first mistake is running a electric gauge.......The most exspensive part of your boat is the motor..............If ya had a mechanical you can rule out all the loose ends arching problems etc.............

It just doesn't sound like an electrical issue. If it were a sender, it would misbehave at lower rpm including idle. Any shorting to chassis would send the needle to one rail or the other and not to some reading within the range of the gauge. I would believe the oil pressure reading you are seeing and track down the reason before doing to many more WOT blasts.

The oil pressure is fine. It no longer has any issues. This went on for almost 2 years and I knew that the oil pressure was fine except that it started "jumping" erratically. It would be perfectly fine at say 4000 rpm, the second you touch the throttle (no increase in rpm yet), the pressure would drop to 0 and bounce back and just keep doing that at a rate that was way too fast to actually be a real drop and rise in oil pressure. Once I recrimped the sender, the problem went away for a while, but ended up coming back. Apparently, when I messed with the wire to the sender, I had moved it to a location that wasn't being affected by the ignition wire. I had actually seen the arc to ground from that wire which is what drove me to change it. My reason for posting is that I finally found the source of the problem and it turned out to be something that I would have thought was very unlikely. Maybe someone else is having a similar problem and can benefit from this experience. I agree that a mechanical guage would be better, but I am not really that worried about it. The way I see it, on a true total loss of pressure, your reaction time is probably too slow to prevent damage and I can see a decreasing pressure trend just fine with what I have. Thanks for the input though,

Rene