DF140 no oil pressure indication

[Biplanepilot]

First post here, glad to find this forum. Earlier this year I had my engine serviced by my local marina, which included an oil change. Of course then I didn't get to use the boat during the summer for one reason or another, but the other day I went out and started it up and guess what... no oil pressure indication on the oil pressure guage. The oil pressure light was out and the engine ran fine. I went out and tooled around for a while without any problems.

My question is how do I test or check the actual oil pressure, and how can I eliminate the oil pressure sender or the guage itself, without just blindly throwing parts at it.

Thanks in advance,

Julian

[JUST-IN-TIME]

oil pressure light should be off

[larrysuzuki]

oil light

Light comes on at 20 hrs and again every 100hrs. It just needs to be reset. Your marina should have done this. I guess they were not a suzuki dealer or well versed about suzuki's.Pull lanyard out turn key on pull in and out red button from where lanyarg goes three times in 15 sec. Just reset once because you have limted resets.

[Biplanepilot]

Thanks for the replies. I haven't been able to get back here for a while. Anyway my problem is not with the light but the guage. No oil pressure is indicated on the guage, but motor runs fine.

[Biplanepilot]

Bumping up this post. Still haven't diagnosed this problem. No indication of oil pressure on the oil pressure gauge. Motor runs fine. I have looked at the shop manual and there is only reference to an oil pressure switch, which is an electrical device. My oil pressure gauge is analog and has a vacuum line attached to it, and is actually measuring pressure. I can't find where the motor end of the vacuum line attaches to on the motor. I suspect the line has just come off at the motor end.

Any ideas where the vacuum line attaches?

Thanks again

[Harper]

Well, it's not a vacuum line. If you have a mechanical gauge, it's a pressure line. If you have an electrical gauge, with a sending unit on the motor, then it's a wire. But I'll go with your observation that, although a rare (and strange) setup, it's a mechanical gauge, and the line of which you speak is a pressure line. So, were it disconnected, there would be oil squirting everywhere under the cowling where it should be attached, or squirting somewhere where the line has broken. Absent the boat or engine being soaked with oil (and eventually losing the engine due to total loss of oil), I'd guess that the line is either blocked, or has never been connected. Since I never like to assume anything, has the gauge worked in the past? Did the boat come with the gauge? I've never seen an outboard with a mechanical oil pressure gauge, because with the continual flexing of the line, it would be too prone to breakage. Most oil pressure gauges on our boats are electronic digital guages, often made to appear in an analog format, with the pressure information being sent via an NMEA 2000 network. If you're not familiar with NMEA 2000 backbone, with screw-on tees and various components used to connect gauges, and other apparatus, you could probably mistake the system as a system of vacuum lines, including the connection to the gauge itself. But, that being said, it has long been known, to the consternation of many Suzuki owners, that Suzukis do not support oil pressure information, or water pressure information, or oil temperature information via the NMEA 2000 network. So, after boring you with all these details (understand, I've been thinking this out as I type) my final diagnosis (guess) is that it is indeed an NMEA 2000 system and since engine oil pressure is just one of those things not available to us Suzuki owners, you have a useless oil pressure gauge. I wish it were different.

[Biplanepilot]

Harper,

Thanks for taking the time to provide such a detailed reply.
This is the deal ...I finally decided to take a day to solve this problem once and for all and this is what I found.

The gauge is a Faria vacuum gauge even though it indicates oil pressure on the dial. I removed the gauge and put a piece of tubing on the nozzle and sucked on it and the needle did indicate vacuum pressure.

I then took the covers off the engine and found that the vacuum line was pinched by the lower right side cover. My marina had performed the last 100 hr inspection and had not taken care in reassembling the covers.

I brought this to their attention and they agreed to cut out the section of damaged line and replace it. And in fact they have just called me as I am writing this to say that they have completed the repair and that the gauge actually measures water pump pressure, not oil pressure.

Problem solved, hopefully.

[Harper]

Glad it's worked out. However somewhat chagrined to be found wrong after such a grand oration.....

[Biplanepilot]

To the contrary you were perfectly correct, Suzuki does not support an analog oil pressure gauge. My gauge is measuring water pressure. Makes perfect sense to me now!