2004 df140 low oil presure

[wellcraftv21]

hello ..I have a 2004 140HP Johnson 4 stroke ..Which is a DF140 just branded Johnson .. My oil light came on indicating low oil pressure. I noticed the oil level was a little high and smelled like gas so I changed filter and oil but alarm still on (even after clearing the code) I pulled the pressure sensor switch and hooked up pressure gauge. At idle speed and not warmed up its reading 50psi and at 3000 rpm it reads 60 psi . My question is at what PSI does the switch turn on the protection feature that doesn't allow rpms above 3000? Seloc says PSI must be at least 78-85PSI . Nothing says what the absolute lowest is without causing terminal damage .Which is why I didn't let the motor warm up ..What am I looking at here ? What should my next step be ? It looks like I have an issue .

PS ..Just purchased the boat so I don't know the history of the motor

[redlowrey]

If your have 50 psi at idle, you have got good clearances, and no excessive bleed offs anywhere. 60 psi is a bit low on 3000 rpm but that is because the pressure reg is dumping oil a bit early nothing to worry about.

The switch is probably faulty, did you check it.

[wellcraftv21]

Red , Thank you for the reply ..I'm a little fuzzy on checking the switch . I'm reading continuity no mater what I do . I have ordered a new one . I'll let you know if it fixes the problem . I

panicked a little at the 60PSI because I didn't know how low was too low .

[wellcraftv21]

it was the switch ! Thank you for the help

[wellcraftv21]

update ..I have taken the boat out twice now since replacing the oil pressure switch and this morning the "no Oil" light came on again and the buzzer sounds for about 12 seconds . Got the boat home put muffs on it and pulled the pressure switch and put in an oil pressure gauge ..still reading 50 psi at idle . with the gauge installed and no swith the buzzer still sounds and the light stays on . What would make the oil pressure light come on with no switch in place ? Motor still runs fine ..no rev limit or anything like that

[Moonlighter]

May be a wiring issue. Your engine is quite a few years old now, and the wiring harness has had a long time to get corrosion into joints and under connectors etc.

Check grounds on the engine, and check all joins in the harness between engine and engine controls and up to the dash. Also check the batteries connections, battery switches, and gauge connections.

There were some joins in the older harnesses half way along that may be difficult to spot and were prone to corrosion in the joins. More info is in the "white wire" sticky thread.

[redlowrey]

update ..I have taken the boat out twice now since replacing the oil pressure switch and this morning the "no Oil" light came on again and the buzzer sounds for about 12 seconds . Got the boat home put muffs on it and pulled the pressure switch and put in an oil pressure gauge ..still reading 50 psi at idle . with the gauge installed and no swith the buzzer still sounds and the light stays on . What would make the oil pressure light come on with no switch in place ? Motor still runs fine ..no rev limit or anything like that

'''''''''Is the light flashing or on continuous, if it is flashing it will be the oil change reminder, if not connect up a digital multimeter and connect it up to the switch wire and see what the voltage is, it should be five volts with the key on. If it is zero the switch wire has gone to ground in the loom somewhere, jiggle the loom and see if the voltage changes while you do it.

[briscoe]

You smelled gas in.oil?

Somebody correct me if I'm wrong. When a low pressure fuel pump acts up it can allow fuel to get into crankcase? Is that check valve acting up. There is a way to test one. I saw something on a UTube about testing it. Just wonder if that would muck up the oil pressure? Probably not, but......

[redlowrey]

Somebody correct me if I'm wrong. When a low pressure fuel pump acts up it can allow fuel to get into crankcase? Is that check valve acting up. There is a way to test one. I saw something on a UTube about testing it. Just wonder if that would muck up the oil pressure? Probably not, but......

''''''''Any engine that has a fuel pump mounted to it, if the diaphragm ruptures will allow fuel to enter the engine and dilute the oil, raise the level and drop the pressure. A df 140 has it mounted on the cam cover.