Electrical failure or what?

[Deep_Blue]

I have an older Merc 90 two stroke, it runs great when it wants to however sometimes after a good run when we idle down even for just a few seconds then try to get back into WOT its has some trouble. It revs to 3-4k RPM and that’s it (every few seconds there’s a very short burst of power but it mainly stays at low RPM). Then after a few minutes and out of no ware it just kicks in and runs normal. Is it electrical? I just changed the switch boxes but I don’t think that was it. thanks.

 

[Clams Canino]

Re: Electrical failure or what?

Toughest thing to find is an electrical thermal intermittant. Run it at WOT on a regular basis and you're asking for more trouble. They cruise nice at 4000 or so.

Next time you wanna go WOT for a long time, just put your car in 2nd gear and floor it for 1/2 hour...

-W

 

[Deep_Blue]

Re: Electrical failure or what?

as i understood, these engines are designed to run hard for most of there life. maybe not WOT but hard. i do a lot of towing behinde the boat but if its hard on my engine maybe ill slow down

 

[jaymasta]

Re: Electrical failure or what?

Next time you wanna go WOT for a long time, just put your car in 2nd gear and floor it for 1/2 hour...

-W

thats pretty much how I drive LOL :^

 

[ricksrster]

Re: Electrical failure or what?

What year is your motor? What is the serial number?

 

[Deep_Blue]

Re: Electrical failure or what?

S# 06514885

How can i find the year from that??

 

[ricksrster]

Re: Electrical failure or what?

Disconnect the blue wire from the switch box. Using an Ohm meter, measure the resistance from the wire to ground. It should read between 5800 - 7000 Ohms. The same with the blue/white. Now do the same with the red and red/white wires to ground. They should read between 135 - 165 ohms.

 

[ricksrster]

Re: Electrical failure or what?

the same post as below

 

[Deep_Blue]

Re: Electrical failure or what?

As much as I hate to question your reality Ricksrster, I must in this event. When you mention its the "same" post as another, yet one post talks about stator and trigger plate and this one well... doesnt even mention them, I don’t see ware the definition of same/identical or even alike come into play.

 

[ricksrster]

Re: Electrical failure or what?

They both relate to an ignition problem . The above test it to test your low speed and high speed coils on your ignition. The triiger resistance should be 800 - 1400 Ohms between brown and purple, white to brown, purple to white. Readings from yellow sleeve wires to black sleeve wires.

 

[Deep_Blue]

Re: Electrical failure or what?

Disconnect the blue wire from the switch box. Using an Ohm meter, measure the resistance from the wire to ground. It should read between 5800 - 7000 Ohms. The same with the blue/white. Now do the same with the red and red/white wires to ground. They should read between 135 - 165 ohms.

I just ran an ohm test on my stator and these are my resaults.

Blue to Red - 7040 ohm
Blue/W to Red/W - No Reading

Red to Gnd - 155.6 ohm
Red/w to Gnd. 157.4 ohm

Blue to Gnd - 6870 ohm
Blue/W to Gnd - 400000 ohm

I guess the Stators blown,

 

[Clams Canino]

Re: Electrical failure or what?

There ya go. And Blue as these engines age it's important to be nice to them. Running ANY engine near redline for extended periods greatly reduces lifespan.

Tubing forever outta be fine. Use WOT to get everything moving and then then back off to about 4200.
That outta give you about 25 miles per hour, which increases a lot on the whips. If you can't throw a tuber at 25, using more speed is cheating. Try bouncing them off a big wake and see how they do.

-W