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2005 bf150 electronically dead. No beep, No crank, no trim, Great compression.

B

BoRkAbkln

New member
Hello experts,

I recently picked up 2 used and unknown condition 2005 honda bf150 motors for cheap cheap. Guy said one ran great, other was acting up, so he repowered with Suzukis.

I have one of the motors on a stand, I drained fuel filters, and drained vst tank.
I pulled the spark plugs to do a compression test.

I hooked up a 12v battery plus to starter and minus to engine block. main ignition harness, with ignition key and shifter all hooked up.

When I turn the key to on or start, absolutely nothing happens, no lights, no buzzer, no crank.
Also trim doesnt do anything from side of motor or Binnacle.

Fuses 1 to 7 are not blown.
Main 90A fuse not blown.

Where should I start?

I did manage to run compression test by shorting positive to exciter plug with pliers to engage the starter. Compression was perfect at 183psi across all 4 cylinders. Oil was dark, not milky. So mechanically engine is good to go. Electrically it seems dead.

I have 2 of these engines, so no problem swapping parts over to experiment.
 
Don't know much about the 150 but supposed to be one of the best Honda built. First thing I would do is to make sure you are getting power to the ECU.

Also, depending on the wiring harness you have, there is a 7.5 amp fuse in that harness near your gauges. If blown not sure that would be responsible for your problem, but worth checking.
 
chawk_man said:
Don't know much about the 150 but supposed to be one of the best Honda built. First thing I would do is to make sure you are getting power to the ECU.

Also, depending on the wiring harness you have, there is a 7.5 amp fuse in that harness near your gauges. If blown not sure that would be responsible for your problem, but worth checking.
Click to expand...

Thanks, I'm pretty sure the ecu is not seeing power, how do I verify power to the ecu?

I don't think its a ignition harness issue, as even without that harness connected to the engine with only the battery cable connected to the starter and engine block, the tilt trim should at least function from the side of the motor switch, and that doesnt even function.
 
I don’t know the answer to this question, but maybe the power connection to the starter only doesn’t backfeed to the tilt?

Start checking for 12v power from your outboard back to your battery?
 
Ok, I figured this out.
The 2005 bf150 has a red 12v cable going to the starter, a black ground going to the engine block from the battery, there is also a white wire with some single round plug to the right side of the ecu that goes to the positive battery terminal.

I was missing the white wire connection, which I'm assuming powers on the ecu.

I was missing that white wire connection.

Now both motors fire up just fine.
 
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