Sporadic ignition - loss of power then right back on again

**rgsauger** · 10-10-2021, 06:58 PM

Hi fellows,
1990 V200, 2.4 Merc carb. Usually runs great. Sometimes after being up over 5K+ RPM or so for a while, when I start slowing down I can tell that the motor is not running right with huge loss of power and seems like dropping a bunch of cylinders. I put my foot back down and she usually picks back up and is ready to roll. Saw it at idle today when I sat it down after running for a while. Ran like chit unless I got the RPM's up. It's literally like it flips a switch and goes from bogging to ready to roll.

Does this sound like a switch box going bad? Or stator? It's literally like it flips a switch. Never does it up top - only after running when the RPM's are coming back down to 3K or less.

16 amp stator. Voltage shows good on Lowrance

Thanks

**rgsauger** · 10-12-2021, 12:11 AM

Bump?

**NeedOne** · 10-12-2021, 06:09 AM

I had a bad stator cause the same condition on 200efi.
Ran like complete garbage at idle and up to 2000 or so rpm. Give it some gas and it ran like nothing wrong.

**Jay Smith** · 10-12-2021, 06:21 AM

When failure occurs kill clean and look at #5 plug and observe color of electrode area if it’s lean look for fuel inventory supply issues if it’s rich look for low voltage issues . Use a external bolt meter to check voltage accurately, with motor not running check at hot side of starter sylinoid and starter ground should be 12.5 volts or more at 1500 rpm idle should be 14 ish , pull cannon 7 pin hooded key switch harness apart clean with brake clean with an ecto knife spread the male terminal to make better contact with female , apply generous amount of dielectric grease reassemble…

good luck ,
Cheers, Jay @ JSRE

**Merc 2.5** · 10-20-2021, 04:36 PM

I've also had a switch box that would miss like crazy under 2k rpm , but anything over it fired on all of em , stator or switch box my guess. Recreate the prob and check the fire to see what's dead

**rgsauger** · 10-20-2021, 09:58 PM

Yeah, 2.5, so there’s a little more to the story. My 40 amp stator took a poop so I swapped to an old 16 amp setup I had laying around. Then I didn’t have fire on one bank. Swapped in an old switchbox I had laying around and then everything lit up again. Then started seeing a little bit of sporadic power loss. Never up top. I prob need to drop for a pair of new boxes and be done with it. Stator ohms our perfectly. 40 amp prob took out the old box.

**scott reierson** · 10-20-2021, 11:08 PM

I had the same thing happen on my twins setup. I chased it all the back to the harness connection at the motor..

That pin# 7 Jay mentions below had a intermittant connection inside the sleeve. I grabbed the connector and wiggled it. There it was. Could see in my dash gauges and a VOM.

I carefully spread all the pins open with razor blade. Cleaned the pins and the insides of female connectors. The problem was gone. I check that now all the time now when I put those connectors together.

Thanks Jay

Originally Posted by Jay Smith

When failure occurs kill clean and look at #5 plug and observe color of electrode area if it’s lean look for fuel inventory supply issues if it’s rich look for low voltage issues . Use a external bolt meter to check voltage accurately, with motor not running check at hot side of starter sylinoid and starter ground should be 12.5 volts or more at 1500 rpm idle should be 14 ish , pull cannon 7 pin hooded key switch harness apart clean with brake clean with an ecto knife spread the male terminal to make better contact with female , apply generous amount of dielectric grease reassemble…

good luck ,
Cheers, Jay @ JSRE

**rgsauger** · 10-21-2021, 07:51 AM

Thanks Scott. I thought I had double checked that connector but I can surely do it again. Only takes a few minutes and removing a mile of black tape. lol

**rjdubiel** · 10-21-2021, 07:54 AM

black tape on the connection? Just unplug the main harness from the boat harness under the cowl, spread the pins. We have also put a hose clamp around the connector once plugged in and tightened that a little to make sure contact is there on worn out harness plugs when the spread the pins does not work or continue to work.

**rgsauger** · 10-21-2021, 08:06 AM

Originally Posted by rjdubiel

black tape on the connection? Just unplug the main harness from the boat harness under the cowl, spread the pins. We have also put a hose clamp around the connector once plugged in and tightened that a little to make sure contact is there on worn out harness plugs when the spread the pins does not work or continue to work.

Same thing you're saying. Just a little extra insurance against the two pieces separating. I've seen hose clamps, zip ties, etc. I just use some black tape around the joint and then an inch or so on either side.

**Jay Smith** · 10-21-2021, 09:21 AM

Your very welcome Scott glad to help !!!
Jay @ JSRE

**65gamblerman** · 10-24-2021, 11:46 AM

Did that fix the problem? I have a similar issue.

**Dave Strong** · 10-24-2021, 12:04 PM

Originally Posted by Jay Smith

Your very welcome Scott glad to help !!!
Jay @ JSRE

Jay did not Mercury have harness to enable you to do DVA tests while running boat? years ago I built a harness to do this on my Bridgeport to find a problem that would only show while running the boat.

Dave

**Jay Smith** · 10-24-2021, 02:49 PM

Yes they did if my febal mind can remember is called a drop test meter it has 6 leads that goes to feed side of all coils , it had a selector rotary switch and volt meter , you install and run the boat when issues happens you observe voltage where ever the selector switch is hooked to then start moving selector switch when you get to the bad actor the volt meter should show a voltage drop , it’s a Mercury diagnostic tool … I’ve got a busy morning but if you will call me mid day I’ll look for it might have an OEM part number attached ..

Jay @ JSRE power