BF90, 2006 Big problem.

Sorry for my english, i'm a french canadian. But i will try by best: Let's go.



I have a BF90 2006 honda (4 carb). When the motor is warm (after 15-20 min) it cut lightly. At the beginning, it's a very small cut but it's worst more the time progress. I must reduce the trottle because the motor cut a lot. The engine continue and drop from 4500 at 2000 RPM rapidly et go again at 4500 in 2 sec. And no alarm never come on.


With my dealer, we change all line gas (entire) and connector, both fuel pomp, spark plug, cap coils, water pump et rebuilt all carb. We try and independant tank and it's the same problem.

AFTER a lot of $$$$ my engine still have the same problem.


When is warm = problem cut, until i am in the obligfation to return at marina with my 9,9HP. So bad......


Is thera have a doctor motor for help me ??

Were the fuel filters and water separators changed?

yes, all piece of alimentation system were changed.

I really don't know anything about the BF 90. However, in these situations there are a couple of basic diagnostics that you should try.

1. When engine starts cutting out, open the filler cap to your fuel tank. If that clears up the problem, then the breather tube on your fuel tank is clogged. Small critters love to build nests in those breather tubes.

2. When engine starts cutting out, feel the primer bulb to see if it is partially collapsed. If so, and you have already tried #1 above, then you could have a clogged pick up tube in your fuel tank or some other restriction in the fuel line between the pick up and the primer bulb.

3. When engine starts cutting out and you have already completed #1 and #2, rapidly squeeze the primer bulb. If engine performs better, then your fuel pump may be failing.

4. I'm not exactly sure how to do this on a BF 90, but install a piece of clear plastic hose in the fuel line between the fuel filter and the carburetors. When engine starts cutting out closely observe the clear plastic fuel line for air bubbles.

Hello Chawk,

1- Step #1 and #2 done. The problem is still there.
2- Step #3 done. The primer bulb sqeeze while cutting don't increase performance.
3- On my boat, la have an internal tank under the floor. For bypass all system and eliminate air bubbles formation, we plug and external tank. The problem is still there.

Thanks for submit some try. With this assay we have eliminate alimentation system problem.

Looks like all of the obvious issues have been addressed.

Some of you 90 owners and experts need to jump on to this one. I'm now beyond my level of competency.

What are your charging voltages like when the engine is cutting out?

Get a timing light and check how the light flickers on each of the plug wires as you make the engine fail. It will take two people to do this safely.

If any one plug wire causes a different flicker, then the problem is in that cylinder....could be carburetor or could be electrical.

If the flicker changes radically on all of them when the engine fails, then you may have an pulser problem or CDI problem. Since the CDI changes low voltage to high voltage, it could be breaking down internally when you accelerate to high rpm.

Mike

Hello Mike,

After some test perform by myself, i found the problem.

When i put an ice pak on my CDI unit the engine is like a new engine.
Engine cut = put ice on CDI = full power ant no cut.

CONCLUSION : CDI unit. Thaks for alls. Mike you got it!!!

Good deal! I like the ice pack test. Never tried that..

Mike