No power under load

[Warmstrong]

Well, I feel like its narrowed down to something electrical; likely the stator. Going to purchase the CDI troubleshooting guide as was recommended and see what values I come up with. One question that I do have that someone here might be able to help with, when I called Mercury to get some part numbers in case I needed to replace the stator, rectifier etc, the told me the part number for the stator was dependent on whether or not I had a voltage regulator. I was able to find the rectifier pretty easily, but Im not sure about the voltage regulator. I posted a pic of the stbd side of the eng a few posts back. Any input on that would be greatly appreciated.

[Merc 2.5]

Rectifier only on urs.

[Warmstrong]

Ok, I dug into the wiring and got the wires from the stator isolated. Total of 6 wires. 2 yellow, 2 red and 2 green. Both the yellow wires attach to the rectifier. The two sets of red and green are further color coded as one set had a thin white line running through, and the other set is solid red and green. I didn't get to pull the wires off and test them tonight, but that will happen as soon as I get off work tomorrow. Does anyone know the resistance values I should be looking for? I plan to call Mercury tomorrow and get the part number for the stator in case it fails the test.

[Warmstrong]

Tested everything and I think I may have found the culprit if Im reading this right. The two yellow wires that went to the rectifier came in at 1.2 ohms, and based on what Ive seen online, that's good for that part of it. After some digging, I believe Im supposed to test the two red wires, and then the two green wires together. With that, I got 280 ohms for red to red, and infinity for green to green. I also tested reds to greens and also got infinity. What I'm guessing is that the red side is working, and is why it will crank and idle so well. That would mean that the green side is bad and most likely the reason I can't get above 2000 rpms. Am I looking at this right? All tests where done with the meter on the 2K ohms setting, and conducted with 2 separate meters, both yielding the same results.

[Capt.Insane-o]

Red is the high speed of the stator and Blue is the low speed.

[kellytheaker]

Good for you for digging and finding the values for checking - i dont profess to be all that knowledgeble in this tech area but you have some members following you on this so yes I believe your on to possible issue other than the idling is good and values you state are out for the low side . Members here will hopefully shed some light on this and direct you further on the assumption of a stator issue . Keep digging but I believe the Captain and another member initially wanted a check on those values initially - they have far more experience and will possibly help confirm

[Motv18]

Captain says red and blue

you said red and green

that may be the issue. The wrong one most of the time won’t work either.

[Warmstrong]

So I went back and double checked, they are blue, not green. Not the best lighting in my garage.

Thanks to some help from some folks, I was able to find the stator values. OEM is 60-150 ohms for the red side, 6000 for the blue side. Knowing that, it was obvious I tested the blue wires on the wrong range (mines not auto). Retested on the 20k setting and got 12.35 (12,350 ohms). So both my blue and red side are above OEM range. The red is a little out and the blue is way high. How do I interpret those values? Do they make sense with the engine starting and idling extremely well, but not going above 2000 rpms? The way I tested each was to connect the red and black leads from the meter to both reds wires, and then both blue wires.

[Capt.Insane-o]

I don't ohm anything unless it is a no spark situation. Output voltages both cranking and running with the components at temperature particularly when crossing the threshold which is usually 18-2200 rpm is the only way to properly diagnose issues. You HAVE to have a dva meter and or adapter and know how to use it for this. In the past couple years on these older motors voltage bleed through the wires to the switchbox housings has become very common.

[Warmstrong]

I decided to call CDI Electronics and spoke with one of their people. I can't stress enough how awesome those folks are. Apparently I had been bench testing the stator incorrectly should have been testing each wire to ground. When doing so I got 140 ohms for each of the red wires, and 6000 ohms for each of the blue wires, which is close to perfect. The tech said that ideally I would test it with the engine at operating temp as Capt alluded to. He then wanted to check something on my switch boxes. We were checking for a short or open circuit between the red and blue posts of both switch boxes. Front box had 160,000 ohms, rear box had infinity even after switching the leads. The tech said this indicated a failed diode I believe and recommended I replace both switch boxes. He was surprised to find out that I had the original Mercury switch boxes, which he said are actually made of paper on the inside and prone to failure. I am going to be ordering two new CDI switch boxes that will hopefully be here by Friday. The plan is to get them installed on Friday and run the boat on Sat and see if that solved the problem. Ill report back with the results.

[mrichartz]

So the wiring harness jumpers were by passing switch boxes?

[roadkill636]

Spend $50 and try a 19 p aluminum prop

[Warmstrong]

So the wiring harness jumpers were by passing switch boxes?

The mechanic that installed the motor gave me the harness he took off. It looks like he jumped over a section of the harness that was burnt or damaged. Right before the plug where it connects to the boat.

[mrichartz]

Oh ok so switch boxes just happened to go between buying and installing on your boat.. definitely not uncommon they go bad all the time... Especially seeing as they are original

[Warmstrong]

Spend $50 and try a 19 p aluminum prop

Prop is getting addressed. Its definitely not the one I want on there anyway. Looking for either a 23p or 24p tempest plus. In speaking with other 361v owners who have 175s, these are the setups I keep hearing good things about.