increased fuel usage and loss of RPM 2000 johnson 150 Ocean Pro

1st. No oil alarm light on, checked oil in tank, ok, engine still smoking. Have noticed increased fuel consumption and loss of RPM. Could not get over 4000RPM at WOT. ( 20ft seapro WA with 150 Ocean Pro). Once RPM did jump to 5300 for a few seconds and then back to 4000. Only did this once. Checked compression, ok, and noticed top cylinder plug looked new. Started engine at night with hose to flush and when engine fired and flame about one foot came from the prop. Any ideas? Sounds to me like raw gas in the exhaust system, why?

Thanks,
First time user, Kevin

Re: increased fuel usage and loss of RPM 2000 johnson 150 Ocean Pro

Kevin, The "No Oil" Alarm means the OMS pump is not seeing oil move thru the pump. It has some sort of motion sensor.

The "low oil" alarm is for when the oil resevoir is low.

I would immediately mix the fuel to 50::1, in case the no oil alarm is accurate, until you fix the motor.

Your problem sounds like intermittent ignition, or perhaps the SLOW system is activated. First mix up some 50::1 fuel and run the motor on the flusher device. See if either head overheats. If both are OK, disconnect the SLOW wire from the head temp sensor to the powerpack and see if that helps problem. Check spark with a timing light, on each plug wire in turn. if plugs look new, you may have bad headgasket allowing water to enter cylinder.

Re: increased fuel usage and loss of RPM 2000 johnson 150 Ocean Pro

mcnameez said:

1st. No oil alarm light on, checked oil in tank, ok, engine still smoking. Have noticed increased fuel consumption and loss of RPM. Could not get over 4000RPM at WOT. ( 20ft seapro WA with 150 Ocean Pro). Once RPM did jump to 5300 for a few seconds and then back to 4000. Only did this once. Checked compression, ok, and noticed top cylinder plug looked new. Started engine at night with hose to flush and when engine fired and flame about one foot came from the prop. Any ideas? Sounds to me like raw gas in the exhaust system, why?

Thanks,
First time user, Kevin

Click to expand...

last tuneup? carbs rebuild? decarb? if none of these in the last months i would definetly do a decarb see if that helps... follow the link below

also sounds like an intermitent ignition problem.... you could try to pull one spark plug wire at the time while on muffs and see if any change.... one of the cylinders might not be working/firing

Re: increased fuel usage and loss of RPM 2000 johnson 150 Ocean Pro

Thanks for the info I will give it a try this weekend. Do you have any idea why I am getting a flame from the prop when I start he motor?

Re: increased fuel usage and loss of RPM 2000 johnson 150 Ocean Pro

I did notice when I removed the top cylinder plug wire I did not notice a change in the motor. But I am getting spark when using a spark tester. Do you have any idea why I am getting a flame out of the prop when I start the motor. Thank you for your response.

Re: increased fuel usage and loss of RPM 2000 johnson 150 Ocean Pro

Flames could be unburnt fuel igniting in the exhaust because its not being burnt in the cylinder.

Re: increased fuel usage and loss of RPM 2000 johnson 150 Ocean Pro

mcnameez said:

I did notice when I removed the top cylinder plug wire I did not notice a change in the motor. But I am getting spark when using a spark tester. Do you have any idea why I am getting a flame out of the prop when I start the motor. Thank you for your response.

Click to expand...

You didn't state what gap you set the spark tester to but I bet its weak spark, it sparks in the fresh air but not under compression,

so look at the coil(remove from engine and examine for cracks), coil ground and plug wire.
If coil looks ok (no cracks) try swapping it around with a good one and see if the problem follows the coil, same with plug wire.

Its igniting raw fuel in the exhaust.
Holy sparkplugs! that must look like the batboat.