oil pressure alarm sender

[makaira1]

I have a 2003 Yanmar 315 with 250 hours. Today while trolling the engine just died. there was no power to the ignition switch and I traced the problem to the oil pressure alarm. Apparently when the oil pressure drops the engine quits. The oil is fine the sender seems to be faulty. This has happened on the last Yanmar I had and has happened to several friends with the 4 cylinder Yanmars. Taping on the sender seems to fix the problem. Obviousley this is a poor design. Any ideas?????

[Mistress]

I don't know anything about the Yanmar. Mine is just an alarm...no ignition cut. Kinda spooky.

You might find out what the resistance value is at some "normal" pressure and make up a "dummy" load to get home on in case tapping on it doesn't do the trick next time.

Is this a seperate snder from the pressure gage?

[Pequod]

No correllation between the alarm and the engine dying. Merely a sender for the gauge and a normally closed sender for the idiot light which powers the light on your panel when you lose pressure. I would check the "run solenoid" that is energized when you turn the key onand de-energized to allow the engine to stop. I just got back from the shop, so I will look at a wiring diagram on monday and give a looksee.

[makaira1]

on the console, I have an alarm panel with a buzzer and several indicator lights. Normally when the key is turned the lights and buzzer activate until the engine starts then they deactivate. The second time this happened, I tapped on this buzzer and then it started to buzz and the engine would start. Any help would be appreciated.

[Mistress]

I have a buzzer too...but it doesn't interrupt power to the ignition. One could do it that way though.

Could you have "wiggled" the gearshift when you rapped the buzzr? maybe it hadn't been in neutral.

[Pequod]

Hey Mistress....................I have the Yanmar Manuel and schematics as well as the wiring for your engine. Let me know what questions you need answered.

[Mistress]

Not me bro. I have a Cummins and my buzzer is aftermarket.

[Pequod]

Sorry Mistress..................I ment Makaira1.........Btw, Cummins is one of the best diesels on the market. Especially at your engines rating @ 220hp?

[Mistress]

YA...210/220. Mechanical/Metric rating.

[Mistress]

[QUOTE=Mistress] but it doesn't interrupt power to the ignition. One could do it that way though.

If the alarm were wired to kill the engine you would need an overide for starting. Otherwise you would have to get oil pressure before it would start. On the new electronic engines I think the computer can be programmed for this function. I think I still prefer mechanical diesels.

Agreed. A delay timer or override would be one way. Using a seperate start circuit vs. run circuit (similar to ballast resistor wiring) would be another. Alot of the computerized engines in cars and I believe the new-tech outboards will go to a limp mode if they detect something as damaging as no oil pressure.

I think the message is that if your engine is wired this way..know it...if it isn't then it isn't the no start problem.

[Pedlyr]

I am not familiar with Yanmar diesels.

Some smaller HP diesels such as Isuzu's did use a solenoid on the fuel pump that must be activated (i.e. retracted or on) for the engine to run. This is how they shutdown if they overheat or lose oil pressure. It was a common occurance on some of the generators I worked with for these solenoids to go bad and not work properly.

They also used a two amperage setting. One to "start" or retract the solenoid and a lower "Holding" amperage to maintain the device in the correct setting. Sometimes this could be wired backwards or incorrect and effect the solenoid performance.

It sounds like you may have a problem somewhere in your shutdown overide at startup. Hope this is helpful. // Ed

[Mistress]

My Cummins has a shutdown solenoid at the injector pump. Nothing to do with oil pressure though (simple alarm).

[makaira1]

Hi, I sent a thread about my yanmar 315. It just stops and at first i thought it was one of the alarm sensors on the engine. Shamrock did not use the Yanmar panel. They used alternate gauges and a seperate alarm indicator panel with an alarm buzzer. Prior to the problem the panel got wet, shorted and buzzed for a while then dried out and quit. I have no wiring diagrams for this and am in the dark. Any help would be great. Thanks. Bob

[Mistress]

PM Pequod. He said he has the schematics.