Loss of RPM

[Barondriver]

Engine related question on my 307 Tourny with F250's.
After running 30-45 minutes at 4000-4500 rpm the starboard engine drops 300-400rpm and flashes the check engine message. No change in temps or pressures. The same problem repeats itself each new trip.

600 hour service was just completed and no error codes were noted other than a few old high temp codes. Thoughts?

 

[raymond@galconconstuction]

mine did the same, pair of 225s, always the port motor,
it was sucking air through a filter seal, threaded wrong, takes a while to see a drop in fuel pressure,
check the water fuel filter, bowl and transom filters

 

[wahoo33417]

If you have the square gauges: Next time the 'check engine' is flashing, hold down the Mode button on the tach for that engine for ten seconds. That should give you a number. From there you can look that number up and learn what the ECU thinks the problem is.

If the engine is dropping rpms, it may not be a major problem, but likely not trivial either.

My engine was doing the same for what turned out to be a cam position sensor.

 

[Barondriver]

If you have the square gauges: Next time the 'check engine' is flashing, hold down the Mode button on the tach for that engine for ten seconds. That should give you a number. From there you can look that number up and learn what the ECU thinks the problem is.

If the engine is dropping rpms, it may not be a major problem, but likely not trivial either.

My engine was doing the same for what turned out to be a cam position sensor.

Thats the frustrating part. No error codes show up.
I’ll pull the cowl this weekend and look for leaks. Im thinking. Sensor May drift after it heats up or a loose connector hopefully. Tx for the replies and I’ll let you know if I find any smoking guns.

 

[g0tagrip]

My starboard F-250 did the same thing, there are three cam position sensors on the back of the engine. I replaced all three and no problems since.

 

[Barondriver]

Problem solved, swapped Cam Sensors between engines and problem traveled with the sensors. New ones on order. Simple fix. tx.

Yamaha PN 6P2-85896-00-00​

Yamaha PN 6P2-85897-00-00​

Mitsubishi J5T24291 - 8702
Mitsubishi J5T23392 - 8724