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2006 BF150 Won't Start unless half throttle

bobmech said:
Before you tear it apart it's probably a good idea to check the crankshaft endfloat for a possible worn out thrust bearing, as that could be a cause or contributor to a failed timing chain, guides, or tensioner.
Hopefully it's OK, but these have been known to fail on the BF150.
Easily checked by gently prying under the crank pulley.

Bob
Click to expand...

How much movement is too much? I will check it tomorrow afternoon.

Thanks

Kurt
 
More than .35 mm movement is too much. It is the crankshaft axial measurement in the specs in your manual.

Also, double check that when the screwdriver is pushed out to the max...the crank shaft pulley mark aligns to its mark. If it does not, it could be possible that the crankshaft pulley key is sheared.

If that checks out ok, then it does look like you are going to have to pulley that cover and see what gives.

Hopefully, the valves/pistons have not been damaged from being out of time.

Fingers crossed for something straightforward and inexpensive.

Mike
 
Pulled the cover today. Didn't see anything obvious. So I removed the tension piston and aligned everything like the books says. Put it all back and started up. It fired right up and idled smooth at 700 RPM. It made a little noise for about 2 seconds on the initial startup, sounded like chain. But very quiet and smooth at idle now. It will die as soon as you give it a little throttle now. Don't know if it jumped timing again and that is the issue or one of the sensors I swapped is bad. I ran out of daylight. So plan is to remove the valve cover tomorrow and verify timing marks are still aligned. If they jumped again, what could be the problem. I would guess the tension piston could be weak. The crank pulley seems to be fine. It didn't have any play. I appreciate all the help and learning a lot about the motor. It may help some day when I am 30 miles offshore.
 
At least it is starting, as it should.

If it jumped timing, could be bad link in the chain, weak tensioner, cracked chain guide or any combination.

Make sure that you connected all of the sensors back up. Of course, if one is disconnected, you should get an alarm.....if that part of the system is working.

Hang in there.

Mike
 
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