89 Mercruiser 350 died under power and wont restart

[vetting]

I have a 89 Mercruiser 350 I/O that suddenly died while under power tonight. Was cruising at about 12 mph and all of the gauges were reading normal. All of a sudden the motor just shut off. Couldnt get it restarted and noticed that the oil pressure gauge wasnt moving like it normally does when I tried to crank it back over. Ended up getting a tow back to the slip and didnt mess with it too much. The motor was running fine with no funky noises. Do carbed motors cut the power if the oil pressure sensor fails? What else should I check in the morning?

 

[HT32BSX115]

Do carbed motors cut the power if the oil pressure sensor fails? What else should I check in the morning?

Howdy,

No, they do not. Your problem sounds a little like an electrical problem, (so I would start there.) Check the main fuse/circuit breaker.

Check all connections especially all the battery connections that they are clean and tight. (including all ground connections) You also have a 10 or 12 pin plug (on the engine) that could possibly be loose.

Use a test light to check for power at the ignition coil + connection (key ON, shifter in neutral)

Get yourself a Mercruiser Service manual (for your serial number engine) If you have a Seloc or Clymer manual, use that for a kneepad or to start your woodstove....

If it turns out to NOT be electrical, look to the fuel system (fuel pickup in the tank, filter, pump, carburetor etc)

Regards,

Rick

 

[Maclin]

Might check to see if there is fuel in the carb. The fuel pump could have quit and the carb ran dry, although there is usually some surging right before that. Take the flame arrestor off and look down the carb throat as you move the throttle halfway, if there is fuel in the carb you should see two nice streams squirting in.

 

[vetting]

That wouldnt explain the no oil gauge movement when trying to restart the boat. I grounded the green wire to the block and the oil gauge pegged to the right.

 

[Maclin]

No, you are right, checking for fuel in the carb would certainly not address that. It would eliminate one of the big 3 missing items (fuel) though.

 

[Bondo]

That wouldnt explain the no oil gauge movement when trying to restart the boat. I grounded the green wire to the block and the oil gauge pegged to the right.

Ayuh,.... That oughta be covered when ya verify power to the ignition, like Rick mentions,....

It takes fuel, fire, compression, 'n all at the right time, for a motor to run,...

Diagnosis verifies each of the 4,....

Rick, 'n Maclin gotcha covered with their advice,....

I'm guessin' it's a simple electrical problem,...
Maybe the grounds are corroded,..... a test light, 'n sandpaper would be a good start,...

 

[vetting]

Went down to the boat with the dog the other day to investigate further. Took off the flame arrestor and saw fuel when pumping the throttle. Then with the ignition on, was getting 12 volts the the purple wire side of the coil. Tried to convince the dog to hold a screwdriver in the coil while I cranked it, but he just wasnt having it Called a buddy down and sure enough, no spark coming out of the coil. Threw a new coil in and it started right up and all of the gauges worked again. Not sure what was going on with the oil pressure gauge originally, but works fine now and appears to be unrelated unless the bad coil was causing that bad of grounding issues.

 

[alldodge]

If it does it again run thru this