rectifier test

I just was checking my rectifier and I am puzzled....

when I have the engine not running it has a constant 12.3v that im assuming coming from my battery.

when I have the engine running I see it drops from 12.4 to 5 to 6 to 12 to 6 etc... always dropping

Is that normal?

mike

Re: rectifier test

No it's not normal. You should see the voltage go up to about 14 volts at 3000 RPMs and as high as 16 volts at WOT with a Rectifier charging system. If you have a Rectifier/Regulator charging system, you should see about 13.5 - 14.5 volts above 3000 RPMs.

From the symptoms that you describe, it sounds like your charging system is not working.

Re: rectifier test

could that also be the reason I have a weak spark?

it idle amazing but at high speeds I cant seam to get her more then 4300 to 45 rpms

stator 720 oms trigger 49-50oms so my resistance are absolutely in specs

Re: rectifier test

Depending on what's wrong with the rectifier, it can affect the output of the stator. The battery charging windings and the ignition system windings are in close proximity on the stator. To test, all you have to do is to disconnect the two leads from the stator to the rectifier. Tape the ends off so they don't short to anything, and try it out and see if you can get a few more RPMs out of it. Have to say though, when the rectifier is bad enough to affect the ignition system, the motor doesn't run that well.

If the motor is running good, but just low RPMs, you need to check several things.
1. What model and length of boat do you have.
2. What horsepower is your motor.
3. How much does your boat weight.
4. What pitch propeller do you have.

Re: rectifier test

In addition to PNW's recommendation you also need to set your trim properly. A boat plowing the water will absolutely has a negative affect on the max rpm at WOT.

Re: rectifier test

trim working perfect..
trophy 18.5 = 2600 with engine lets saw 3k ith everything
force 125
prop is 13.1/4*17

thx

Re: rectifier test

I would say that you're probably not going to get much more out of your motor. You may want to try a 15 pitch prop if you have one available.

I have an 19ft Bayliner Cobra, basically a Capri but different seating arrangement, with a 1988 125HP motor. It weighs about 2000lbs. You're pushing more weight, plus the Trophy hull has a deeper "V",so it cuts through the waves, where as the Capri's have a shallower "V" and ride more on top of the waves which is less drag but rougher ride in the waves. I think max. RPMs that I could get with a 13.25 X 17 pitch aluminum prop was in the neighborhood of 5200 - 5500 RPMs.

You may be a tad low in your maximum RPMs, but all in all, I don't think your motor has got a problem. I could be wrong, but maybe some of the other folks here might have a similar set up as yours. It would be interesting to see what they're experiencing. That would probably be the most accurate information. At this point I wouldn't assume that the reason the motor won't achieve higher RPMs is due to a problem with the motor.

Maybe replacing that Force 125HP with one of these would be the ticket.

Seven Marine - The Most Powerful Outboards on the Planet

Re: rectifier test

pnboat this forum is only for force motors!!!

hahahahahaha

I have a guy lives close to me we have all the same stator and trigger reading and he is going a whopping 5200

I hope a crack this because girlfriend is losing her patience with me and my mistress boat

hhahaha

Re: rectifier test

Just kidding about replacing your motor. Wouldn't we all like to have that much horsepower available!

Anyways, back to your problem. Does your buddy have the same boat (Trophy), motor (Force 125HP) and prop pitch as yours?

Re: rectifier test

yup that why im leaning towards some kind energy issue

he even has the same spark plugs...

mike

Re: rectifier test

Try having someone squeeze the primer bulb while your at WOT. If that helps, then you need to look at fuel delivery. Fuel pump check valves, fuel pump diaphragm, fuel tank pick up tube, fuel tank vent.

With the engine shut off, does the primer bulb get firm after squeezing 4 or 5 times?

Also try disconnecting the stator leads connected to the rectifier.

Re: rectifier test

pnwboat said:

Try having someone squeeze the primer bulb while your at WOT. If that helps, then you need to look at fuel delivery. Fuel pump check valves, fuel pump diaphragm, fuel tank pick up tube, fuel tank vent.

With the engine shut off, does the primer bulb get firm after squeezing 4 or 5 times?

Also try disconnecting the stator leads connected to the rectifier.

Click to expand...

check valves are the only thing I did not replace...

bulb stay nice and hard threw out any cycle..... but the check valves can be faulty?

did change diaphram

Re: rectifier test

Well next time you take it out, disconnect the leads from the stator to the rectifier, or better yet, go to Radio Shack and get a replacement full wave bridge rectifier. P/N 276-1185 for $4.49 + tax.

25A, 50V Full-Wave Bridge Rectifiers : Rectifiers | RadioShack.com

I would still try squeezing the primer bulb at WOT to see if it will make a difference.....it doesn't hurt to check.