Motor running hot, bogging down after decarb

[Cady8special]

Hey guys,

Just picked up a 1999 Mercury 135HP V6 Carbed model. I ran it for about 30 minutes the first time out. Bogged a little out of the hole but got up to speed ok. Last night, I ran a decarb- one bottle in 3/4 gallon of gas method- 15 minutes at high idle, 15 minutes off. I kept checking the heads and tell tale- everything was warm- not hot. After the third 15 minute cycle, I hooked up the main gas line again and tried to blow it out. I got to about 2500 RPM's I'd guess, and it started to bog down and wouldn't even plane. I didn't want to push it for fear that the carb was clogged. I checked the heads and they were pretty hot. About 5 seconds is all I could take with my hand on the head. Starboard side felt a bit hotter. Good tell tale stream- new pump. Would you guys suspect a clogged carb? Also, not sure if this is relevant or not, but the top and bottom plugs on the starboard side were flashing while it was running. Does this mean anything? I was thinking about taking it out today- just booting it for about 20 seconds to see if it clears itself out. If it gets hot, I'll get it cool down before puttering back. What do you guys think?

Thanks.

 

[Cady8special]

Also, could this be a stuck thermostat? It pisses, but it mostly just when I rev it up. It's not a steady hard stream like I've had in the past.

 

[sullmate]

it could be the t stats or perhaps the poppet valve. I have the same engine only 1997 vintage. the flashing (arching) could be bad ignition wires

 

[CharlieB]

Any 'new to you' motor should have the carbs cleaned, fuel pump rebuilt and the water pump serviced, just to be sure all is well.

While a de-carb works well to remove carbon deposits in the cyls and pistin rings, it does not do a thorough job of carb cleaning. Often dislodging chunks of accumulated mineral and further clogging jets.

Service the motor, do a complete link and synch.

 

[MikDee]

Sounds like you have arcing, crossfiring, at the plugs. What condition are the wires in? If they are okay, then you need to check that the spark plugs are not cracked or oily, greasy, give them all a wipe with alcohol. Also, are they resistor plugs? I strongly recommend resistor plugs to prevent arcing, or crossfiring, especially with metallic wires. They tend to send all the spark to the firing tip. Let me know what you find?

 

[Texasmark]

Replacing the spark plugs is recommended in the site listed decarb process. Very possibly your decarb fouled one or more plugs and they don't fire. Not firing allows the spark voltage applied to rise to max (40,000 volts, not 18,000 or thereabouts when the plug fires), not be limited by the firing plug. This higher than usual/normal is probably what is causing your problem "all of a sudden". I wouldn't run it any more till you replace them so that you don't punch arc holes in your otherwise good high voltage circuit insulation.

Mark

 

[Texasmark]

Duplicate post; still having software issues.