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Does motor shut down due to failed oil sensor switch?


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I was headed back to the dock after skiing yesterday morning at about 30mph and the engine shut down and wouldn’t restart.  I lifted the doghouse and see oil floating on top of the water I normally have in the bilge (need to change my shaft packing in the off season).  I get towed home and start to investigate.  The engine was a quart low on oil and see it draining pretty quickly out of the oil sensor switch while cranking the boat.   The engine would not restart after adding the quart of oil.  The switch must have failed because the threaded stud in the center of the sensor that holds the wire is “loose” 

Would this failed sensor actually shut down the boat and prevent a restart?  I’ve heard of people getting constant alarms but I can’t find an instance where the motor actually shuts down to protect the engine. 
I couldn’t find the part available yesterday but should be able to pick up a Napa equivalent today.  Just wondering if this will solve my problem or I have something else going on also?
 

Edited by Badger
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2 minutes ago, tvano said:

if the oil pressure switch has failed it should signal the ecm that oil pressure is too low.

the ecm should then kill power to the fuel pump.

yup, i think you have found your problem.

I have never been able to verify your second sentence.

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It would have to be in the ECM's software because there is no direct electrical connection between the oil pressure switch and the fuel pump. Grounding out the wire to the oil pressure switch would answer the question.

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8 minutes ago, electricjohn said:

It would have to be in the ECM's software because there is no direct electrical connection between the oil pressure switch and the fuel pump. Grounding out the wire to the oil pressure switch would answer the question.

With your screen name of "electricjohn", I expect you to be able to answer my questions regarding ignition systems and electric connections!  Not the other way around.  I will take care of all your questions related to the Badgers!

Just joking with you.  NAPA had to order the part and I won't get it until tomorrow to test these theories.

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I replaced the oil sensor today and the boat still does not start.  I checked all the normal things, neutral, lanyard, etc.   

Any ideas?

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Does your fuel pump run 2 seconds when you turn the key on?  That will verify good fuses and relays.  If so, I would then look at ignition components, ie coil, cap and rotor, module.  Does it crank?

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Mine went out in my 98 and caused a CEL, but the boat always ran. Coincidentally the same threads finally failed around the same time  I figured out the switch was the cause of the CEL.
According to the MEFI 2 wiring diagram it should just trigger the CEL. Don’t t that changed much with MEFI 3.   

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interesting thread - I have a hesitation sometimes from idle when pulling up a skier and one person said that changing the oil pressure switch fixed their similar problem.   

Edited by SkiPablo
typo
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11 hours ago, CoMtnBu said:

Mine went out in my 98 and caused a CEL, but the boat always ran. Coincidentally the same threads finally failed around the same time  I figured out the switch was the cause of the CEL.
According to the MEFI 2 wiring diagram it should just trigger the CEL. Don’t t that changed much with MEFI 3.   

What's a CEL?

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short on time at the moment so i'm not able to search.

i'd swear that i've both read and promoted the "oil pressure switch induces ecm to power the fuel pump" on tmc.

hope i have not been spewing disinformation for decades.

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When I took my first test (acceptance) ride in my boat, the beeper went off constantly. Dealer told me it's OK and he will fix it when I get back.  It was a bad oil pressure switch, but I was still able to go through the full throttle range during my ride.  He fixed it by unplugging it. Eventually I found a wire diagram and realized what he did.

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3 minutes ago, tvano said:

i'd swear that i've both read and promoted the "oil pressure switch induces ecm to power the fuel pump" on tmc.

It definitely allows the pump to come online after starting...the question is if it cuts the fuel pump totally, or sends engine into limp mode.  I read somewhere that it doesn't cut the engine due to safety/liability.  @Badger hasn't answered if the pump is coning on during key up.  If not, then it's not the oil pressure switch.

 

INDMAR (CHEVY) ENGINE START UP SEQUENCE


Fuel Rail Pressurization:

When you first turn the key to the "on" position (aka “key up”), the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Schrader valve on the fuel rail near and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running. Test by attaching a fuel pressure gauge to the fuel rail at the shrader valve, on TPI and LT1 engines its located on the pass side fuel rail.

Initial Crank Action:

If you then rotate the key to the start position the engine will rotate.  Once the oil pressure has reached 4 PSI, the oil pressure switch will close allowing the fuel pump to run.  The crank position sensor will send a string of pulses to the ECM in response to the engine being rotated by the starter. These pulses continue as long as the engine turns (both starting and running) and if they are not present, the engine will not run.

ECM Reaction:

If the ECM sees oil pressure greater than 4 PSI and the reference pulses from the distributor, it will energize the injector drivers which will begin pulsing the injectors on for 4 ms (milliseconds) periods. The ECM will also pull in the fuel pump relay in effect paralleling it electrically with the oil pressure switch.  The ECM also monitors the TPS (Throttle Position Sensor mounted on the throttle body assembly) and wants to see .54 volts at this time. If it sees more than 0.54 volts, it will assume the engine is flooded.  Assuming the ignition module is good the engine will "catch".

Engine "Catches":

When the engine catches, the MAF sends a signal to the ECM advising that air is flowing and also just how much air is being pulled through to the intake manifold. The ECM takes note of the amount of air being consumed and adjusts the injector pulse width to around 2.2 ms nominally so as to attain a proper air/fuel mixture to insure combustion.  The engine should show an initial idle speed of around 900-1100 RPM and then slowly diminish to 600-700 RPM.  If this does not happen, the Idle Air Mixture valve may be mis-adjusted. Alternatively, there may be a leak in the intake manifold or another vacuum leak may be present. Listen for hissing sounds---there should be none.

ECM Mode:

The engine will now be in Open Loop mode meaning that the ECM is controlling the air/fuel mixture by referencing values stored in memory.  Once the Oxygen sensor <if you have Cats> reaches operating temperature of several hundred degrees, the Manifold Air Temperature (MAT) sensor shows an intake air temperature of more than 140 degrees and the Engine Coolant Temperature (ECT) has reached 160 degrees, the computer will switch to closed loop mode meaning the Oxygen sensor's output is examined along with the MAT and ECT outputs and the ECM adjusts the injector pulse widths (more "on time" or less "on time") to constantly strive for a 14.7:1 air/fuel mixture which is the best mixture to hold down pollution.

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Thanks guys. I haven’t read through allOf the detail above. I am in the boat right now and do not have any fuel pressure at the rails. I am depressing the Schrader valve and would expect to get sprayed in the face with gas. I’ve got nothing. Looking for a fuse for the fuel pump right now.But also starting to rain, LOL need to move the boat back under the lift canopy

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Ok, so I found a fuse block with the help of @tvano that had 3 blade style fuses in it that were all fine. 

I've never used a test light before but hooked the alligator clip to an allen screw on the exhaust manifold and tried both leads to the high pressure fuel pump while someone first keyed the engine on and then cranked over the engine.  Nothing in either position.  I then checked the test light on the starter to see if I was using it correctly and the light came on.  By this time, it was getting dark and we had company coming so I quit for the night. 

The fuel pump leads seem to be painted.  I'm assuming that the paint isn't enough to cause the test light not to work or do I need scrape some off and try it again?

I didn't try following wires back yet but I'm guessing I need to keep backing up to see where the power stops.  Is that likely going to be at the ECM?

I'm still wondering if the failed oil pressure switch is related to this problem or if it had been leaking for some time and is completely unrelated.

Any recommended next steps?

Edited by Badger
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First things first, do you get power to the dash gauges when you key up?

I really don't like the way you tested for power to the fuel pump.  Here is what I suggest:

  1. Remove power plug to fuel pump.
  2. Using alligator clips, connect plug that would normally power fuel pump to voltmeter.
  3. Have someone KEY UP and you should get power for 2 seconds (and 2 seconds only.)
  4. If no power, then check fuel pump relay; in fact I would change it just to eliminate it as a possibility.
  5. Re-check for power again.
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